ANTENNA

CROSS-REFERENCE TO RELATED APPLICATIONS

The instant application claims the benefit of priority to U.S. Provisional Application No. 60/865,168 filed on 10 November 2006, which is incorporated herein by reference. The following applications are also incorporated herein by reference: U.S. Application Serial No. 11/382,011, filed on 5 May 2006; U.S. Provisional Application Serial No. 60/594,783, filed on 5 May 2005; U.S. Application Serial No. 11/161,681, filed on 11 August 2005; and U.S. Provisional Application No. 60/522,077, filed on 11 August 2004.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 illustrates a side view of a first embodiment of a multi-beam antenna;

FIG. 2a illustrates a plan view of a discrete lens array of the first embodiment of the multi-beam antenna;

FIGS. 2b and 2c illustrate cross-sectional views of the first embodiment of the multi- beam antenna;

FIG. 3 illustrates an expanded side view of a portion of the discrete lens array portion illustrated in FIG. 2b;

FIG. 4 illustrates an expanded cross-sectional plan view of a portion of the discrete lens array portion illustrated in FIG. 3; FIG. 5 illustrates an expanded side view of a portion of the multi-element broadside feed array portion illustrated in FIG. 2b;

FIG. 6 illustrates an operation of the first embodiment of the multi-beam antenna;

FIG. 7a illustrates a side cross-sectional view of a second embodiment of a multi- beam antenna; FIG. 7b illustrates a plan cross-sectional view of a multi-element broadside feed array of the second embodiment of the multi-beam antenna;

FIG. 7c illustrates a plan view of a discrete lens array of the second embodiment of the multi-beam antenna;

FIG. 8 illustrates a second aspect of a multi-beam antenna;

FIG. 9 illustrates a plan view of a multi-element broadside feed array and associated circuitry of the second aspect of the multi-beam antenna illustrated in FIG. 8;

FIG. 10 illustrates a cross-sectional view of a third embodiment of a multi-beam antenna; FIG. 11 illustrates a phased-array portion of a multi-element broadside feed array;

FIG. 12 illustrates an elevational side view of a fourth embodiment of a multi-beam antenna;

FIG. 13 illustrates a fragmentary side cross-sectional view of a second aspect of a discrete lens array; FIG. 14 illustrates a block diagram of a discrete lens array;

FIG. 15a illustrates a plan view of a first side of one embodiment of a planar discrete lens array;

FIG. 15b illustrates a plan view of a second side of one embodiment of a planar discrete lens array; FIG. 16 illustrates a plot of delay as a function of radial location on the planar discrete lens array illustrated in FIGS. 15a and 15b;

FIG. 17 illustrates a fragmentary cross sectional isometric view of a first embodiment of a discrete lens antenna element;

FIG. 18 illustrates an isometric view of the first embodiment of a discrete lens antenna element illustrated in FIG. 17, isolated from associated dielectric substrates;

FIG. 19 illustrates an isometric view of a second embodiment of a discrete lens antenna element;

FIG. 20 illustrates an isometric view of a third embodiment of a discrete lens antenna element, isolated from associated dielectric substrates; FIG. 21 illustrates a cross sectional view of the third embodiment of the discrete lens antenna element;

FIG. 22 illustrates a plan view of a second embodiment of a discrete lens array;

FIG. 23 illustrates an isometric view of a fourth embodiment of a discrete lens antenna element, isolated from associated dielectric substrates;

FIG. 24a illustrates a cross sectional view of the fourth embodiment of the discrete lens antenna element of a third embodiment of a discrete lens array;

FIG. 24b illustrates a cross sectional view of the fourth embodiment of a discrete lens antenna element of a fourth embodiment of a discrete lens array; FIG. 25 illustrates a plan view of the conductive elements of a first embodiment of a second aspect of a broadside feed antenna;

FIG. 26 illustrates a cross-sectional view of the second aspect of a broadside feed antenna;

FIG. 27 illustrates a third aspect of a multi-beam antenna; FIG. 28 illustrates a plan view of first embodiment of a multi-element broadside feed array incorporated in the embodiment of the third aspect of the multi-beam antenna illustrated in FIG. 27;

FIG. 29 illustrates a plan view of the conductive elements of a second embodiment of the second aspect of a broadside feed antenna; FIGS. 30a and 30b respectively illustrate E-plane and H-plane radiation patterns from a simulated operation of the second aspect of a broadside feed antenna;

FIGS. 31a and 31b illustrate far-field radiation patterns from a simulated operation of the third aspect of a broadside feed antenna for scan angles of 0 degrees and 24 degrees, respectively; FIG. 32a illustrates a rear plan view of a discrete lens array in accordance with a fourth aspect of a multi-beam antenna;

FIGS. 32b and 32c illustrate side and top views, respectively, of the fourth aspect of a multi-beam antenna;

FIG. 33a illustrates a rear plan view of a discrete lens array in accordance with a fifth aspect of a multi-beam antenna;

FIGS. 33b and 33c illustrate side and top views, respectively, of the fifth aspect of a multi-beam antenna;

FIG. 34 illustrates a first embodiment of a dual-polarized broadside antenna element;

FIG. 35a illustrates an isometric view of conductive elements associated with a second embodiment of a dual-polarized broadside antenna element;

FIG. 35b illustrate a cross-section of the second embodiment of a dual-polarized broadside antenna element; FIG. 36a illustrates plan view of an example of a polarization twist reflector;

FIG. 36b illustrates a cross-sectional view of the example of a polarization twist reflector illustrated in FIG. 36a;

FIG. 37 illustrates a first embodiment of a dual-polarized lens element; FIG. 38 illustrates a second embodiment of a dual-polarized lens element; FIG. 39a illustrates a rear plan view of a discrete lens array in accordance with a sixth aspect of a multi-beam antenna;

FIGS. 39b and 39c illustrate side and top views, respectively, of the sixth aspect of a multi-beam antenna;

FIG. 40a illustrates a rear plan view of a discrete lens array in accordance with a seventh aspect of a multi-beam antenna;

FIGS. 40b and 40c illustrate side and top views, respectively, of the seventh aspect of a multi-beam antenna;

FIG. 41a illustrates a rear plan view of a discrete lens array in accordance with an eighth aspect of a multi-beam antenna; FIGS. 41b and 41c illustrate side and top views, respectively, of the eighth aspect of a multi-beam antenna;

FIG. 42 illustrates a first embodiment of a vertical polarizer;

FIG. 43a illustrates a plan view of a second embodiment of a vertical polarizer;

FIG. 43b illustrates a cross-section through the second embodiment of the vertical polarizer illustrated in FIG. 43a;

FIG. 44a illustrates a rear plan view of a discrete lens array in accordance with a ninth aspect of a multi-beam antenna; and

FIGS. 44b and 41c illustrate side and top views, respectively, of the ninth aspect of a multi-beam antenna.

DETAILED DESCRIPTION OF EMBODIMENT(S)

Referring to FIGS. 1-6, a multi-beam antenna 10 comprises a multi-element broadside feed array 12 adapted to cooperate with a discrete lens array 14 through a block of dielectric material 16, wherein the multi-element broadside feed array 12 and the discrete lens array 14 are each operatively coupled to opposing sides of the block of dielectric material 16. The multi-beam antenna 10 can be adapted for operation in a transmit mode, a receive mode, or both a transmit mode and a receive mode either in sequence or simultaneously. In a transmit mode, each broadside feed antenna 18 of the multi-element broadside feed array 12 provides for generating a different beam of electromagnetic energy 20 in a different direction as focused by the discrete lens array 14. In a receive mode, each broadside feed antenna 18 of the multi-element broadside feed array 12 provides for receiving a different beam of electromagnetic energy 20 through the discrete lens array 14 from a corresponding different direction. In one embodiment, the discrete lens array 14 is located substantially along the focal plane of the discrete lens array 14, i.e. at a distance f therefrom, wherein f is equal to the focal length of the discrete lens array 14. In another embodiment, the discrete lens array 14 is located substantially along a focal surface of the discrete lens array 14, i.e. so that each of the elements of the discrete lens array 14 is substantially at a focal point of the discrete lens array 14 relative to an associated beam of electromagnetic energy 20 associated with a corresponding direction.

A first embodiment of the multi-beam antenna 10' is illustrated in FIGS. 1-6. The discrete lens array 14 comprises an assembly of a first set 22.1 of first broadside antenna elements 24.1 on a first side 26.1 of the discrete lens array 14, and a corresponding second set 22.2 of second broadside antenna elements 24.2 on a second side 26.2 of the discrete lens array 14, wherein the first 26.1 and second 26.2 sides face in opposing directions with respect to one another, and the first 24.1 and second 24.2 broadside antenna elements from the first 22.1 and second 22.2 sets are paired with one another. The first 24.1 and second 24.2 broadside antenna elements of each pair 28 are adapted to communicate with one another through an associated delay element 30, wherein the amount of delay, or phase shift, is a function of the location of the particular pair 28 of first 24.1 and second 24.2 broadside antenna elements in the discrete lens array 14 so as to emulate the behavior of an electromagnetic lens, for example, a spherical, piano-spherical, elliptical, cylindrical or piano-cylindrical lens. The delay as a function of location on the discrete lens array 14 is

adapted to provide — in a transmit mode — for transforming a diverging beam of beam of electromagnetic energy 20 from an associated broadside feed antenna 18 at a focal point to a corresponding substantially collimated beam exiting the discrete lens array 14; and vice versa in a receive mode. Referring to FIGS. 2-4, in accordance a first aspect, the discrete lens array 14 comprises a first set 22.1 of first broadside antenna elements 24.1, for example, patch antenna elements, on a first side 32.1 of a first dielectric substrate 32 and a second set 22.2 of second broadside antenna elements 24.2, for example, patch antenna elements, on a first side 34.1 of a second dielectric substrate 34, with the respective second sides 32.2, 34.2 of the first 32 and second 34 dielectric substrates facing one another across opposing sides of a central conductive layer 36 that is provided with associated coupling slots 38 associated with each pair 28 of first 24.1 and second 24.2 broadside antenna elements, wherein the associated coupling slots 38 provide for communication between the first 24.1 and second 24.2 broadside antenna elements of each pair 28, and are adapted to provide for the corresponding associated delay, for example, in accordance with the technical paper, "A planar filter-lens-array for millimeter-wave applications," by A. Abbaspour-Tamijani, K. Sarabandi, and G.M. Rebeiz in 2004 AP-S Int. Symp. Dig., Monterey, CA, June 2004, which is incorporated herein by reference. For example, referring to FIG. 4, in accordance with one embodiment, the coupling slots 38 are "U-shaped" — i.e. similar to the end of a tuning fork — and in cooperation with the adjacent first 32 and second 34 dielectric substrates constitute a sandwiched coplanar-waveguide (CPW) resonant structure, wherein the associated phase delay can be adjusted by scaling the associated coupling slot 38. Accordingly, the individual pairs 28 of first 24.1 and second 24.2 broadside antenna elements in combination with an associated delay element 30 constitute a bandpass filter with radiative ports which can each be modeled as a three-pole filter based upon the corresponding three resonators of the associated first 24.1 and second 24.2 broadside antenna elements and the associated coupling slot 38.

For example, the first 32 and second 34 dielectric substrates may be constructed of a material with relatively low loss at an operating frequency, examples of which include DUROID ^® , a TEFLON ^® containing material, and a ceramic material, depending upon the frequency of operation. For example, in one embodiment, the first 32 and second 34 dielectric substrates comprise DUROID ^® with a TEFLON ^® substrate of about 15-20 mil thickness and a relative dielectric constant of about 2.2, wherein the first 24.1 and second

24.2 broadside antenna elements and the coupling slots 38 are formed, for example, by subtractive technology, for example, chemical or ion etching, or stamping; or additive techniques, for example, deposition, bonding or lamination, from associated conductive layers bonded to the associated first 32 and second 34 dielectric substrates. The first 24.1 and second 24.2 broadside antenna elements may, for example, comprise microstrip patches, dipoles or slots.

The first side 26.1 of the discrete lens array 14 is bonded to a first surface 40 of the block of dielectric material 16 using a bonding agent 42, for example, having a dielectric constant substantially equal to that of the block of dielectric material 16. The first broadside antenna elements 24.1 are adapted so as to be substantially impedance-matched to the block of dielectric material 16, and the second broadside antenna elements 24.2 are adapted so as to be substantially impedance-matched to air.

The block of dielectric material 16 is adapted so as to provide for locating the multielement broadside feed array 12 substantially along the focal plane of the discrete lens array 14. In one embodiment, the block of dielectric material 16 comprises a slab with a thickness substantially equal to the focal length f of the discrete lens array 14, for example, having an aspect ratio — given by the ratio f/D of the focal length f to the diameter D of the discrete lens array 14 — greater than 0.25. For example, for a multi-beam antenna 10 with f/D of about 0.4 - 0.6 and an aperture diameter of about 4 inches, the corresponding thickness of the block of dielectric material 16 would be about 1.6 - 2.4 inches. A larger f/D provides for better scanning off-axis, but requires a thicker structure. The particular thickness of the block of dielectric material 16 for a particular application, could and typically would, for example, be calculated using ray-tracing and full- wave electromagnetic models. The block of dielectric material 16, for example, comprises a material with relatively low loss at an operating frequency, for example, a TEFLON ^® containing material or a ceramic material, depending upon the frequency of operation. For example, TEFLON ^® has been useful at microwave and mm-wave frequencies, although some other material with a similar relatively dielectric constant and a similar loss tangent would provide similar results. In one embodiment, the block of dielectric material 16 comprises a cylindrical disk 44 with parallel planar faces 46, sliced from a cylindrical rod of TEFLON ^® , wherein the separately fabricated multi-element broadside feed array 12 and discrete lens array 14 are respectively bonded to respective opposing parallel planar faces 46 of the cylindrical disk 44. Excessive undesirable reflections from the cylindrical side surface 48 of the cylindrical

disk 44, if present, could be mitigated by rounding or angling the cylindrical side surface 48, or by incorporating quarter-wave grooves therein so a to provide for a better match to the surrounding air. Furthermore, an absorber material could be added around the cylindrical side surface 48 so as to provide for mitigating a spillover of electromagnetic energy. Referring to FIGS. 2b, 2c, 5 and 6, the multi-element broadside feed array 12 comprises a plurality of broadside feed antenna 18 on a third dielectric substrate 50, formed, for example, by subtractive technology, for example, chemical or ion etching, or stamping; or additive techniques, for example, deposition, bonding or lamination, from an associated conductive layer bonded to the associated third dielectric substrate 50. For example, the third dielectric substrate 50 would comprise a material with relatively low loss at an operating frequency, for example, DUROID ^® , a TEFLON ^® containing material, a ceramic material, depending upon the frequency of operation. The multi-element broadside feed array 12 on the third dielectric substrate 50 is bonded with a bonding agent 42 to the second surface 52 of the block of dielectric material 16, and is substantially aligned with the center of the discrete lens array 14.

The broadside feed antennas 18 of the multi-element broadside feed array 12 are, for example, located along a linear array in the X-direction, Y-direction; located in accordance with a 2-dimensional spacing; or located in accordance with any combination therefore (ie, a cross), so as to provide for scanning in azimuth or elevation, or two dimensional scanning. For linear (e.g. IxN, 2xN, or 3xN) and cross-arrays (N in the X; N in the Y), there would be sufficient space to integrate the associated front-end electronic components 54, e.g. transmit and receive electronics, and the switch network for the broadside feed antennas 18, with the multi-element broadside feed array 12 on the third dielectric substrate 50. For example, the broadside feed antennas 18 may comprise either dipole (or double-dipoles or folded-dipoles) antennas, slot (or double-slots or folded slots) antennas, microstrip-type antennas, patch antennas, or any other type of a broadside radiating antenna, wherein the broadside feed antennas 18 are adapted to radiate efficiently within the block of dielectric material 16, wherein the particular design would be adapted for the particular operating frequency. For example, in one embodiment, the broadside feed antennas 18 comprise single or paired rectangular or square conductive patches. In another embodiment, slot feeds might be used.

In accordance with one process, the multi-element broadside feed array 12 and the discrete lens array 14 are each first fabricated separately, and then both are respectively

bonded to respective first 40 and second 52 surfaces on opposing sides of the block of dielectric material 16, so as to create an integral multi-beam antenna 10 assembly that provides for maintaining the alignment of the multi-element broadside feed array 12 with respect to the discrete lens array 14, thereby precluding the need for subsequent alignment thereof. Conventional printed circuit board (PCB) construction and assembly processes can be used for the construction and alignment of the multi-element broadside feed array 12 and the discrete lens array 14, and the assembly of the multi-beam antenna 10, which provides for improved reliability and reduced cost thereof.

The multi-beam antenna 10 may further comprise a switching network having at least one input and a plurality of outputs, wherein the at least one input is operatively connected — for example, via at least one transmission line — to a corporate antenna feed port, and each output of the plurality of outputs is connected — for example, via at least one transmission line — to a respective feed port of a different broadside feed antenna 18 of the plurality of broadside feed antennas 18. The switching network further comprises at least one control port for controlling which outputs are connected to the at least one input at a given time. The switching network may, for example, comprise either a plurality of micro- mechanical switches, PIN diode switches, transistor switches, or a combination thereof, and may, for example, be operatively connected to the dielectric substrate, for example, by surface mount to an associated conductive layer of a printed circuit board. In operation, a feed signal applied to the corporate antenna feed port is either blocked

— for example, by an open circuit, by reflection or by absorption, — or switched to the associated feed port of one or more broadside feed antennas 18, via one or more associated transmission lines, by the switching network, responsive to a control signal applied to the control port. It should be understood that the feed signal may either comprise a single signal common to each broadside feed antenna 18, or a plurality of signals associated with different broadside feed antennas 18. Each broadside feed antenna 18 to which the feed signal is applied launches an associated electromagnetic wave into the first side 26.1 of the associated discrete lens array 14, which is diffracted thereby to form an associated beam of electromagnetic energy 20. The associated beams of electromagnetic energy 20 launched by different broadside feed antennas 18 propagate in different associated directions. The various beams of electromagnetic energy 20 may be generated individually at different times so as to provide for a scanned beam of electromagnetic energy 20. Alternatively, two or more beams of electromagnetic energy 20 may be generated simultaneously. Moreover,

different broadside feed antennas 18 may be driven by different frequencies that, for example, are either directly switched to the respective broadside feed antennas 18, or switched via an associated switching network having a plurality of inputs, at least some of which are connected to different feed signals. The multi-beam antenna 10 may be adapted so that the respective signals are associated with the respective broadside feed antennas 18 in a one-to-one relationship, thereby precluding the need for an associated switching network. For example, each broadside feed antenna 18 can be operative Iy connected to an associated signal through an associated processing element. As one example, with the multi-beam antenna 10 configured as an imaging array, the respective broadside feed antennas 18 are used to receive electromagnetic energy, and the respective processing elements comprise detectors. As another example, with the multi-beam antenna 10 configured as a communication antenna, the respective broadside feed antennas 18 are used to both transmit and receive electromagnetic energy, and the respective processing elements comprise transmit/receive modules or transceivers. The switching network, if used, need not be collocated on a common dielectric substrate, but can be separately located, as, for example, may be useful for low frequency applications, for example, for operating frequencies less than 20 GHz, e.g. 1- 20 GHz.

Referring to FIGS. 7a-7c, in accordance with a second embodiment of a multi- beam antenna 10", the multi-element broadside feed array 12 and associated front-end electronic components 54 are constructed on the third dielectric substrate 50, which then cooperates with a separate fourth dielectric substrate 56 containing associated baseband electronic components 58. More particularly, the broadside feed antennas 18, e.g. patch antennas, are located on a first side 60 of the third dielectric substrate 50 comprising a relatively low dielectric constant material, e.g. DUROID ^® , and the associated front-end electronic components 54, e.g. an associated beam switching network and transceiver, are installed on the opposing second side 62 of the third dielectric substrate 50 and adapted to communicate with the associated broadside feed antennas 18 via either conductive feedlines (e.g. via's) or other electromagnetic coupling (e.g. radiative coupling as illustrated in FIGS. 3 and 4 for the discrete lens array 14) through the third dielectric substrate 50. The fourth dielectric substrate 56 incorporates a cutout 64 adapted to provide clearance for the front- end electronic components 54 on the second side 62 of the third dielectric substrate 50, so as to provide for assembling the third 50 and fourth 56 dielectric substrates to one another

and providing for the electrical coupling of signals therebetween. For example, the fourth dielectric substrate 56 could be constructed from a glass-epoxy circuit board, e.g. FR4, adapted to incorporate the associated baseband electronic components 58, e.g. power supplies, control logic, or processing circuitry. Referring to FIG. 7b, the multi-element broadside feed array 12 comprises a cross- shaped array of seven broadside feed antennas 18.1 adapted to provide or receive an associated seven different beams of electromagnetic energy 20, each at a different azimuthal angle, and all at a common central elevational angle; and three broadside feed antennas 18.1, 18.2, 18.3 adapted to provide or receive an associated three different beams of electromagnetic energy 20, each at a different elevational angle, and all at a common central azimuthal angle, responsive to associated beam control by an associated switching network of the front-end electronic components 54, for example, as described more fully hereinbelow.

Referring to FIG. 8, the multi-element broadside feed array 12 of a second aspect of a multi-beam antenna 200 is adapted so that different broadside feed antennas 18 are oriented in different directions in accordance with the focal surface of the associated discrete lens array 14 so as to provide for increasing the range of scan angles of the multi-beam antenna 200, particularly for broadside feed antennas 18 that are relatively distant from the central axis of the discrete lens array 14 that would otherwise be located substantially displaced from the associated focal surface of the associated discrete lens array 14. Furthermore, referring to FIG. 9, the associated third dielectric substrate 50 is adapted so that all of the associated front-end electronic components 54, e.g. the associated beam selection switches 66 and transceiver 68, are located on a common first side 60 of the third dielectric substrate 50, with a common ground plane on the opposing second side 62. A first portion 70 of the third dielectric substrate 50 containing the broadside feed antennas 18 is separated from a second portion 72 of the third dielectric substrate 50 by the necked portion 74 thereof which, for example, is provided for by a plurality of notches 76 or slits, wherein the necked portion 74 is adapted to be sufficiently wide so as to provide sufficient space for the necessary transmission lines 78, e.g. microstrip lines, along the necked portion 74, connecting the beam selection switches 66 on the second portion 72 of the third dielectric substrate 50 to the broadside feed antennas 18 on the first portion 70 of the third dielectric substrate 50. For example, each transmission line 78 may comprise either a stripline, a microstrip line, an inverted microstrip line, a slotline, an image line, an

insulated image line, a tapped image line, a coplanar stripline, or a coplanar waveguide line formed in or on the third dielectric substrate 50, for example, from a printed circuit board, for example, by subtractive technology, for example, chemical or ion etching, or stamping; or additive techniques, for example, deposition, bonding or lamination. The necked portion 74 enables the first 70 and second 72 portions of the third dielectric substrate 50 to flex relative to one another, so that the second portion 72 of the third dielectric substrate 50 can remain relative flat so as to provide for an operatively coupling thereof to the associated fourth dielectric substrate 56, e.g. FR4 circuit board, as described hereinabove in accordance with the second embodiment of the multi-beam antenna 10" illustrated in FIGS. 7a and 7b; whereas the first portion 70 of the third dielectric substrate 50 can be curved, for example, by mounting to an appropriately curved support 80, e.g. constructed of either metal or some other material. The ground plane on the second side 62 of the second portion 72 of the third dielectric substrate 50 can be bonded to a corresponding ground plane of the fourth dielectric substrate 56, for example, with conductive epoxy or solder. In the embodiment illustrated in FIG. 8, the multi-element broadside feed array 12 is radiatively coupled to the discrete lens array 14 through an air gap 82, for example, in accordance the U.S. Application Serial No. 11/161,681, which is incorporated herein by reference.

Alternatively, referring to FIG. 10, in accordance with a third embodiment of a multi-beam antenna 10' ", the third dielectric substrate 50 and associated multi-element broadside feed array 12 may be attached to a curved second surface 52 of a plano-convex block of dielectric material 16' having a discrete lens array 14 operatively coupled to the opposing first surface 40, so as to provide for maintaining the alignment of the multielement broadside feed array 12 with respect to the discrete lens array 14. The phase delay profile of the discrete lens array 14 would be adapted to account for and cooperate with the phase delays associated with the plano-convex block of dielectric material 16'.

Referring to FIG. 11, in any of the embodiments for which the relatively distal broadside feed antennas 18 are sufficiently displaced from the focal surface of the discrete lens array 14 so as to excessively disrupt the associated radiation pattern of the associated beam of electromagnetic energy 20, pluralities, e.g. adjacent pairs 84, of broadside feed antennas 18 can be phased so as to direct the associated beam of electromagnetic energy 20, or the directivity of the associated broadside feed antennas 18, towards the center of the discrete lens array 14.

One first embodiment of the multi-beam antenna 10' provides for +/- fifty (50) degree scanning in an elevation, azimuth, or a diagonal direction, although a scan range of at least +/- sixty (60) degrees is likely achievable. The multi-beam antenna 10, 200 is suitable for automotive collision avoidance systems, automatic cruise control, and other automotive applications, for example, at 24 GHz, 60 GHz and 77 GHz. The multi-beam antenna 10, 200 may be adapted with a radome, e.g. a thick low loss plastic coating, so as to provide for environmental protection thereof.

Referring FIG. 12, in accordance with a fourth embodiment of a multi-beam antenna 10"", a plurality of linear multi-element broadside feed arrays 12.1, 12.2, 12.3 - each providing for generating one or more corresponding beams of electromagnetic energy 20 in a corresponding one or more associated azimuthal directions — are adapted to cooperate with a discrete lens array 14 through a block of dielectric material 16, so as to provide for generating corresponding sets 20.1, 20.2, 20.3 of beams of electromagnetic energy 20, each in corresponding one or more associated elevational directions. For example, a first multi- element broadside feed array 12.1 comprises a corresponding one or more associated first broadside feed antennas 18.1, each providing for generating a corresponding beam of electromagnetic energy 20 in a different azimuthal direction, all in a first elevational direction 86.1, which, for example, in the origination illustrated in FIG. 12 is directed substantially horizontal. A second multi-element broadside feed array 12.2 comprises a corresponding one or more associated second broadside feed antennas 18.2, each providing for generating a corresponding beam of electromagnetic energy 20 in a different azimuthal direction, all in a second elevational direction 86.2, which, for example, in the origination illustrated in FIG. 12 is directed downwards from horizontal. A third multi-element broadside feed array 12.3 comprises a corresponding one or more associated third broadside feed antennas 18.3, each providing for generating a corresponding beam of electromagnetic energy 20 in a different azimuthal direction, all in a third elevational direction 86.3, which, for example, in the origination illustrated in FIG. 12 is directed upwards from horizontal. Each of the multi-element broadside feed arrays 12.1, 12.2, 12.3 is operatively coupled to a corresponding associated set of beam selection switches 66.1, 66.2, 66.3, each of which is operatively coupled via associated feed 88 and control 90 lines to an associated switch network 92 having associated feed 94 and control 96 signals. Responsive to a control input signal 96, the switch network 92 selects the beam selection switches 66.1, 66.2, 66.3 to which the control signal 96 is applied, thereby controlling which

of the multi-element broadside feed arrays 12.1, 12.2, 12.3 is operatively associated with the feed 94 and control 96 signals, thereby controlling which of the sets 20.1, 20.2, 20.3 of beams of electromagnetic energy 20 are either generated or received in a corresponding elevational direction or set of elevational directions, and the control signals 96 applied to the beam selection switches 66.1, 66.2, 66.3 control which of the associated broadside feed antennas 18.1, 18.2, 18.3 are activated to either generate or receive a corresponding beam of electromagnetic energy 20 in a corresponding selected azimuthal direction. The beam selection switches 66.1, 66.2, 66.3 and the switch network 92 may be integrated with the associated multi-element broadside feed arrays 12.1, 12.2, 12.3, for example, in the front- end electronic components 54 as illustrated in FIG. 7a, wherein the beam selection switches 66.1, 66.2, 66.3 and the switch network 92 are interconnected and operatively coupled to the associated broadside feed antennas 18.1, 18.2, 18.3 with associated transmission lines 78. In an alternative embodiment, the switch network 92 may be connected to the broadside feed antennas 18.1, 18.2, 18.3 directly, without using the intermediate beam selection switches 66.1, 66.2, 66.3 and associated control lines 90. Accordingly, the fourth embodiment of the multi-beam antenna 10"" provides for transmitting or receiving one or more beams of electromagnetic energy 20 over a three- dimensional space.

Referring to FIG. 13, in accordance with a second aspect of a discrete lens array 14, the first 24.1 and second 24.2 broadside antenna elements of each pair 28 communicate through associated transmission line delay elements 30, the length of which is adapted so as to provide for the associated delay. For example, a planar lens 14.1 comprises a first set of patch antennas 102.1 on a first side 104 of the planar lens 14.1, and a second set of patch antennas 102.2 on the second side 106 of the planar lens 14.1, where the first 104 and second 106 sides are opposite one another. The individual patch antennas 102 of the first

102.1 and second 102.2 sets of patch antennas are in one-to-one correspondence. Referring to FIG. 14, each patch antenna 102, 102.1 on the first side 104 of the planar lens 14.1 is operatively coupled via a delay element 108 to a corresponding patch antenna 102, 102.2 on the second side 106 of the planar lens 14.1, wherein the patch antenna 102, 102.1 on the first side 104 of the planar lens 14.1 is substantially aligned with the corresponding patch antenna 102, 102.2 on the second side 106 of the planar lens 14.1.

In operation, electromagnetic energy that is radiated upon one of the patch antennas 102, e.g. a first patch antenna 102.1 on the first side 104 of the planar lens 14.1, is

received thereby, and a signal responsive thereto is coupled via — and delayed by — the delay element 108 to the corresponding patch antenna 102, e.g. the second patch antenna 102.2, wherein the amount of delay by the delay element 108 is dependent upon the location of the corresponding patch antennas 102 on the respective first 104 and second 106 sides of the planar lens 14.1. The signal coupled to the second patch antenna 102.2 is then radiated thereby from the second side 106 of the planar lens 14.1. Stated in another way, the planar lens 14.1 comprises a plurality of lens elements 110, wherein each lens element 110 comprises a first patch antenna element 102.1 operatively coupled to a corresponding second patch antenna element 102.2 via at least one delay element 108, wherein the first 102.1 and second 102.2 patch antenna elements are substantially opposed to one another on opposite sides of the planar lens 14.1.

Referring also to FIGS. 15a and 15b, in a first embodiment of a planar lens 14.1, the patch antennas 102.1, 102.2 comprise conductive surfaces on a dielectric substrate 112, and the delay element 108 coupling the patch antennas 102.1, 102.2 of the first 104 and second 106 sides of the planar lens 14.1 comprise delay lines 114, e.g. microstrip or stipline structures, that are located adjacent to the associated patch antennas 102.1, 102.2 on the underlying dielectric substrate 112. The first ends 116.1 of the delay lines 114 are connected to the corresponding patch antennas 102.1, 102.2, and the second ends 116.2 of the delay lines 114 are interconnected to one another with a conductive path, for example, with a conductive via 118 though the dielectric substrate 112. FIGS. 15a and 15b illustrate the delay lines 114 arranged so as to provide for feeding the associated first 102.1 and second 102.2 sets of patch antennas at the same relative locations.

Referring to FIG. 16, the amount of delay caused by the associated delay elements 108 is made dependent upon the location of the associated patch antenna 102 in the planar lens 14.1, and, for example, is set by the length of the associated delay lines 114, as illustrated by the configuration illustrated in FIGS. 15a and 15b, so as to emulate the phase properties of a convex electromagnetic lens, e.g. a spherical lens. The shape of the delay profile illustrated in FIG. 16 can be of various configurations, for example, 1) uniform for all radial directions, thereby emulating a spherical lens; 2) adapted to incorporate an azimuthal dependence, e.g. so as to emulate an elliptical lens; or 3) adapted to provide for focusing in one direction only, e.g. in the elevation plane of the multi-beam antenna, e.g. so as to emulate a cylindrical lens.

Referring to FIGS. 17 and 18, a first embodiment of a lens element HO ¹ of the planar lens 14.1 illustrated in FIGS. 15a and 15b comprises first 102.1 and second 102.2 patch antenna elements on the outer surfaces of a core assembly 120 comprising first

112.1 and second 112.2 dielectric substrates on both sides of a conductive ground plane 122 sandwiched therebetween. A first delay line 114.1 on the first side 104 of the planar lens 14.1 extends circumferentially from a first location 124.1 on the periphery of the first patch antenna element 102.1 to a first end 118.1 of a conductive via 118 extending through the core assembly 120, and a second delay line 114.2 on the second side 106 of the planar lens 14.1 extends circumferentially from a second location 124.2 on the periphery of the second patch antenna element 102.2 to a second end 118.2 of the conductive via 118. Accordingly, the combination of the first 114.1 and second 114.2 delay lines interconnected by the conductive via 118 constitutes the associated delay element 108 of the lens element 110, and the amount of delay of the delay element 108 is generally responsive to the cumulative circumferential lengths of the associated first 114.1 and second 114.2 delay lines and the conductive via 118. For example, the delay element 108 may comprise at least one transmission line comprising either a stripline, a microstrip line, an inverted microstrip line, a slotline, an image line, an insulated image line, a tapped image line, a coplanar stripline, or a coplanar waveguide line formed on the dielectric substrate(s) 112, 112.1, 112.2, for example, from a printed circuit board, for example, by subtractive technology, for example, chemical or ion etching, or stamping; or additive techniques, for example, deposition, bonding or lamination.

Referring to FIG. 19, in accordance with a second embodiment of a lens element 110 ^π of the planar lens 14.1, the first 102.1 and second 102.2 patch antenna elements may be interconnected with one another so as to provide for dual polarization, for example, as disclosed in the technical paper "Multibeam Antennas with Polarization and Angle Diversity" by Darko Popovic and Zoya Popovic in IEEE Transactions on Antenna and Propagation, Vol. 50, No. 5, May 2002, which is incorporated herein by reference. A first location 126.1 on an edge of the first patch antenna element 102.1 is connected via first 128.1 and second

128.2 delay lines to a first location 130.1 on the second patch antenna element 102.2, and a second location 126.2 on an edge of the first patch antenna element 102.1 is connected via third 128.3 and fourth 128.4 delay lines to a second location 130.2 on the second patch antenna element 102.2, wherein, for example, the first 126.1 and second 126.2 locations on the first patch antenna element 102.1 are substantially orthogonal with respect

to one another, as are the corresponding first 130.1 and second 130.2 locations on the second patch antenna element 102.2. The first 128.1 and second 128.2 delay lines are interconnected with a first conductive via 132.1 that extends through associated first 134.1 and second 134.2 dielectric substrates and through a conductive ground plane 136 located therebetween. Similarly, the third 128.3 and fourth 128.4 delay lines are interconnected with a second conductive via 132.2 that also extends through the associated first 134.1 and second 134.2 dielectric substrates and through the conductive ground plane 136. In the embodiment illustrated in FIG. 19, the first location 126.1 on the first patch antenna element 102.1 is shown substantially orthogonal to the first location 130.1 on the second patch antenna element 102.2 so that the polarization of the radiation from the second patch antenna element 102.2 is orthogonal with respect to that of the radiation incident upon the first patch antenna element 102.1. However, it should be understood that the first locations 126.1 and 130.1 could be aligned with one another, or could be oriented at some other angle with respect to one another. Referring to FIGS. 20 and 21, in accordance with a third embodiment of a lens element 110 ^m of the planar lens 14.1, one or more delay lines 114 may be located between the first 102.1 and second 102.2 patch antenna elements — rather than adjacent thereto as in the first and second embodiments of the lens element HO ¹ , HO ¹¹ — so that the delay lines 114 are shadowed by the associated first 102.1 and second 102.2 patch antenna elements. For example, in one embodiment, the first patch antenna element 102.1 on a first side 136.1 of a first dielectric substrate 136 is connected with a first conductive via 138.1 through the first dielectric substrate 136 to a first end 140.1 of a first delay line 140 located between the second side 136.2 of the first dielectric substrate 136 and a first side 142.1 of a second dielectric substrate 142. Similarly, the second patch antenna element 102.2 on a first side 144.1 of a third dielectric substrate 144 is connected with a second conductive via 138.2 through the third dielectric substrate 144 to a first end 146.1 of a second delay line 146 located between the second side 144.2 of the third dielectric substrate 144 and a first side 148.1 of a fourth dielectric substrate 148. A third conductive via 138.3 interconnects the second ends 140.2, 146.2 of the first 140 and second 146 delay lines, and extends through the second 142 and fourth 148 dielectric substrates, and through a conductive ground plane 150 located between the second sides 142.2, 148.2 of the second 142 and fourth 148 dielectric substrates. The first 140 and second 146 delay lines are shadowed by the first 102.1 and second 102.2 patch antenna elements, and

therefore do not substantially affect the respective radiation patterns of the first 102.1 and second 102.2 patch antenna elements.

Referring to FIG. 22, in accordance with a second embodiment of a planar lens 14.2, the patch antennas 102 are hexagonally shaped so as to provide for a more densely packed discrete lens array 14. The particular shape of the individual patch antennas 102 is not limiting, and for example, can be circular, rectangular, square, triangular, pentagonal, hexagonal, or some other polygonal shape or an arbitrary shape.

Notwithstanding that FIGS. 13, 15a, 15b, and 17-21 illustrate a plurality of delay lines 114.1, 114.2, 128.1, 128.2, 128.3, 128.4, 140, 146 interconnecting the first 102.1 and second 102.2 patch antenna elements, it should be understood that a single delay line 114 - - e.g. located on a surface of one of the dielectric substrates 112, 134, 136, 142, 144 — could be used, interconnected to the first 102.1 and second 102.2 patch antenna elements with associated conductive paths.

Referring to FIGS. 23, 24a and 24b, in accordance with a fourth embodiment of a lens element 110^ of the planar lens 14.1, the first 102.1 and second 102.2 patch antenna elements are interconnected with a delay line 152 located therebetweeen, wherein a first end 152.1 of the delay line 152 is connected with a first conductive via 154.1 to the first patch antenna element 102.1 and a second end 152.2 of the delay line 152 is connected with a second conductive via 154.2 to the second patch antenna element 102.2. Referring to FIG. 24a, in accordance with a third embodiment of a planar lens 14.3 incorporating the fourth embodiment of the lens element 110 ^IV , the first patch antenna element 102.1 is located on a first side 156.1 of a first dielectric substrate 156, and the second patch antenna element 102.2 is located on a first side 158.1 of a second dielectric substrate 158. The delay line 152 is located between the second side 156.2 of the first dielectric substrate 156 and a first side 160.1 of a third dielectric substrate 160 and the first conductive via 154.1 extends through the first dielectric substrate 156. A conductive ground plane 162 is located between the second sides 158.2, 160.2 of the second 158 and third 160 dielectric substrates, respectively, and the second conductive via 154.2 extends through the second 158 and third 160 dielectric substrates and through the conductive ground plane 162. Referring to FIG. 24b, a fourth embodiment of a planar lens 14.4 incorporates the fourth embodiment of a lens element 110^ illustrated in FIG. 23, without the third dielectric substrate 160 of the third embodiment of the planar lens 14.3 illustrated in FIG. 24a, wherein the delay line 152 and the conductive ground plane 162 are coplanar between the

second sides 156.2, 158.2 of the first 156 and second 158 dielectric substrates, and are insulated or separated from one another.

The discrete lens array 14 does not necessarily have to incorporate a conductive ground plane 122, 136, 150, 162. For example, in the fourth embodiment of a planar lens 14.4 illustrated in FIG. 24b, the conductive ground plane 162 is optional, particularly if a closely packed array of patch antennas 102 were used as illustrated in FIG. 22. Furthermore, the first embodiment of a lens element HO ¹ illustrated in FIG. 18 could be constructed with the first 102.1 and second 102.2 patch antenna elements on opposing sides of a single dielectric substrate 112. It should be understood that if the number of broadside feed antennas 18 of the multi-element broadside feed array 12 is reduced to one, the multi-beam antenna 10 will become a single-beam antenna 10 so as to provide for either generating or receiving a single beam of electromagnetic energy 20.

Referring to FIGS. 25-29, in accordance with a second aspect of a broadside feed antenna 18', a plurality of broadside feed antenna elements 164 are operatively coupled to a common antenna feed 166 and associated power divider 168 by a plurality of corresponding feedlines 170, wherein the relative phasing of the respective broadside feed antenna elements 164 relative to the common antenna feed 166 is controlled responsive to the associated effective lengths of the associated feedlines 170 which are fixed by the physical configuration thereof, wherein the relative phasing of the associated feedlines 170 determines the orientation of the associated pattern of the broadside feed antenna 18', i.e. the direction of radiation of associated electromagnetic waves radiated therefrom, or the direction of greatest gain when receiving electromagnetic waves thereby. For example, referring to FIGS. 25-28, in accordance with a first embodiment of the second aspect of a broadside feed antenna 18', a broadside feed antenna 172 comprises a plurality of three associated broadside feed antenna elements 164.1, 164.2, 164.3 arranged in a generally triangular pattern 174, wherein the lengths of the associated feedlines 170.1, 170.2, 170.3 determine the relative phasing of the broadside feed antenna elements 164.1, 164.2, 164.3 relative to the associated common antenna feed 166. The antenna feed 166 is adapted as a three-way power divider 168.1 which, in a transmit mode, provides for distributing power - for example, substantially evenly — from the antenna feed 166 to each of the associated broadside feed antenna elements 164.1, 164.2, 164.3, and which, in a receive mode, provides for combining power from each of the broadside feed antenna elements 164.1,

164.2, 164.3 into the common antenna feed 166. For example, referring to FIG. 26, the three broadside feed antenna elements 164.1, 164.2, 164.3 comprise associated microstrip conductive patches 176 located on a first surface 178.1 of a first dielectric substrate 178, the antenna feed 166 and associated feedlines 170.1, 170.2, 170.3 connected thereto comprise associated interconnected microstrip conductors on a first surface 180.1 of a second dielectric substrate 180, and the feedlines 170.1, 170.2, 170.3 are connected to the corresponding associated respective broadside feed antenna elements 164.1, 164.2, 164.3 with associated respective conductive vias 182.1, 182.2, 182.3 therebetween extending through an associated conductive ground plane 184 sandwiched between the associated second surfaces 178.2, 180.2 of the first 178 and second 180 dielectric substrates, wherein each conductive via 182.1, 182.2, 182.3 is extends through a corresponding via hole 186 in the conductive ground plane 184. For example, in one embodiment, the first 178 and second 180 dielectric substrates are constructed from DUROID ^® having a relative dielectric constant of e _r =2.2. The three-way power divider 168.1 is provided by the configuration of the junction between the feedlines 170.1, 170.2, 170.3 and the antenna feed 166. It should be understood that FIG. 25 illustrates the antenna feed 166, feedlines 170.1, 170.2, 170.3, conductive vias 182.1, 182.2, 182.3 and broadside feed antenna elements 164.1, 164.2, 164.3 in the absence of the first 178 and second 180 dielectric substrates and the conductive ground plane 184, for the sake of clarity. The locations where the conductive vias 182.1, 182.2, 182.3 are connected to the corresponding respective broadside feed antenna elements 164.1, 164.2, 164.3 determines the associated directions and types polarizations thereof, wherein, in the embodiment illustrated in FIG. 25, each of the broadside feed antenna elements 164.1, 164.2, 164.3 is linearly polarized in the direction of polarization 188 indicated therein. Although FIGS. 25 and 26 illustrate an embodiment wherein the feedlines 170.1,

170.2, 170.3 are operatively coupled to the corresponding associated broadside feed antenna elements 164.1, 164.2, 164.3 using associated conductive vias 182.1, 182.2, 182.3, alternatively, the feedlines 170.1, 170.2, 170.3 could be operatively coupled to the corresponding associated broadside feed antenna elements 164.1, 164.2, 164.3 using associated slots in the associated conductive ground plane 184.

Referring to FIG. 27, in accordance with a third aspect of a multi-beam antenna 300, a multi-element broadside feed array 12' comprising a plurality of broadside feed antennas 172 is used in cooperation with a discrete lens array 14, wherein the relative

phasing of the associated feedlines 170.1, 170.2, 170.3 for the corresponding broadside feed antennas 172 are adapted — for example, by setting the relative lengths thereof — so that different broadside feed antennas 172 are directed in different directions, so that each broadside feed antenna 172 is steered towards the center of the discrete lens array 14, so as to provide for proper focusing thereof and so as to prevent or mitigate against excessive spillover of electromagnetic radiation around the edge of the discrete lens array 14, which would otherwise reduce gain and increase associated sidelobe levels, particularly for broadside feed antennas 172 associated with relatively large scan angles. For example, each broadside feed antenna 172 may be constructed in accordance with the second aspect of the broadside feed antenna 18' illustrated in FIGS. 25 and 26. The triangular patterns 174 of the associated broadside feed antenna elements 164.1, 164.2, 164.3 of the broadside feed antennas 172 in the embodiment illustrated in FIGS. 27 and 28 provide for spacing the broadside feed antennas 172 more closely together than would otherwise be possible, by locating a base 190 of the triangular pattern 174 associated with one broadside feed antenna 172 proximate to an apex 192 of the triangular pattern 174 associated with an adjacent broadside feed antennas 172, which may be necessary in order to provide for sufficient overlap of adjacent relatively narrow beams of electromagnetic energy. The multi- beam antenna 300 may either incorporate a block of dielectric material 16 to operatively couple the multi-element broadside feed array 12' to the discrete lens array 14, or the multi-element broadside feed array 12' and the discrete lens array 14 may cooperate with one another via an air gap 82.

For example, in the embodiment illustrated in FIGS. 27 and 28, the directivity of a central broadside feed antenna 172.1 is substantially aligned with the axis 194 of the discrete lens array 14, the directivities of the next outermost broadside feed antennas 172.2, 172.3 are oriented 12 degrees towards the axis 194 of the discrete lens array 14, the directivities of the next outermost broadside feed antennas 172.4, 172.5 are oriented 24 degrees towards the axis 194 of the discrete lens array 14, and the directivities of the next outermost broadside feed antennas 172.6, 172.7 are oriented 36 degrees towards the axis 194 of the discrete lens array 14, wherein, for 24 GHz operation, the corresponding associated offsets 196.1, 196.2, 196.3 of the successively skewed broadside feed antennas 172.2, 172.3; 172.4, 172.5 and 172.6, 172.7, relative to the central broadside feed antenna 172.1, are respectively 0.4 inches, 0.8 inches and 1.3 inches respectively, which is not exactly linear with respect to the associated angle of directivity with respect to the axis 194 of the

discrete lens array 14. The above-described orientations of the broadside feed antennas

172 as illustrated in FIG. 28 provides for substantially the same center-to-center spacing as would be possible with single patch broadside feed antennas 18, e.g. about 0.44 wavelengths, with relatively low mutual coupling therebetween, and with improved utilization of the discrete lens array 14 as a result of the associated directivities being substantially aligned with the center of the discrete lens array 14, or substantially normal to the associated focal surface of the discrete lens array 14, which provides for the lateral extent of the broadside feed antennas 172 in the focal plane of the discrete lens array 14 to be as large as that of the discrete lens array 14. Although in the embodiment illustrated in FIGS. 27 and 28, the relative phasing of the associated feedlines 170.1, 170.2, 170.3 is used to control the directivities of the associated broadside feed antennas 172 along one direction, e.g. along an azimuthal direction, it should be understood that the triangular pattern 174 of associated broadside feed antenna elements 164.1, 164.2, 164.3 provides for controlling the directivities in either the azimuthal or the elevational direction, or in both the azimuthal and elevational directions.

Referring to FIG. 29, illustrated similarly to FIG. 25, in accordance with a second embodiment of the second aspect of broadside feed antenna 18', 172', the broadside feed antenna 172' may comprise four associated broadside feed antenna elements 164.1, 164.2, 164.3, 164.4, arranged generally in a quadrilateral pattern, for example, a square or rectangular pattern 198, wherein the broadside feed antenna elements 164.1, 164.2, 164.3, 164.4 are fed from a common antenna feed 166/ power divider 168, using corresponding respective feedlines 170.1, 170.2, 170.3, 170.4, the relative lengths of which are adapted so as to provide for controlling the relative phasing of the respective associated broadside feed antenna elements 164.1, 164.2, 164.3, 164.4 so as to provide for controlling the directivity of the multi-element broadside feed antenna 172' in either the azimuthal or the elevational direction, or in both the azimuthal and elevational directions.

The simulated operation of a broadside feed antenna 172 of FIGS. 25-28 incorporating a triangular pattern 174 of broadside feed antenna elements 164.1, 164.2,

164.3 is illustrated in FIGS. 30a and 30b, the former of which illustrates the E-plane and H- plane radiation patterns of a broadside feed antenna 172.1 that is phased to provide for broadside directivity (i.e. 0 degree scan angle relative to normal), resulting in a directivity of

10 dB; and the latter of which illustrates the E-plane radiation pattern of a broadside feed

antenna 172 that is phased to provide for a directivity that is skewed 20 degrees relative to normal, resulting in a directivity of 9.5 dB.

The simulated operation of the third aspect of the multi-beam antenna 300 using broadside feed antennas 172 incorporating a triangular pattern 174 of broadside feed antenna elements 164.1, 164.2, 164.3 is illustrated in FIGS. 31a and 31b in comparison with the simulated operation of a first aspect of the multi-beam antenna 10 incorporating a single element broadside feed antenna 18, wherein FIG. 31a illustrates a far-field radiation pattern for operation at a scan angle of 0 degrees, and FIG. 31b illustrates a far- field radiation pattern for operation at 24 degrees, both of which are for operation at 24 GHZ using a 2.7 inch diameter discrete lens array 14, wherein it can be seen that the broadside feed antenna 172 incorporating a triangular pattern 174 of broadside feed antenna elements 164.1, 164.2, 164.3 provides for 2 dB greater gain than the single element broadside feed antenna 18, and therefor which provides for a 4 dB greater signal-to-noise ratio in radar applications than the single element broadside feed antenna 18. Referring to FIGS. 32a-c, in accordance with a fourth aspect of a multi-beam antenna 400, by applying folded optics to the multi-beam antenna 400 and placing the associated multi-element broadside feed array 12, 12' coplanar with the discrete lens array 14, the overall depth of the multi-beam antenna 400 can be cut in half relative to the third aspect of the multi-beam antenna 300. More particularly, one or more of the first broadside antenna elements 24.1 of the associated discrete lens array 14 is/are replaced with, or are adapted to function as, one or more broadside feed antennas 18, 18' which radiate electromagnetic energy 402.1 backwards away from the discrete lens array 14 towards an associated reflector 404 located at about half of the focal length f of the discrete lens array 14 therefrom, which then reflects the electromagnetic energy 402.2 forwards towards the discrete lens array 14. With the reflector 404 located about half of the focal length f of the discrete lens array 14 therefrom, the electromagnetic energy from the broadside feed antennas 18, 18' travels about one focal length f before reaching the discrete lens array 14, which focuses the reflected electromagnetic energy 402.2 into an associated one or more beams of electromagnetic energy 20. In the embodiment illustrated in FIGS. 32a-c, the multi-element broadside feed array 12, 12' comprises three broadside feed antennas 18, 18', one at the center of the discrete lens array 14, and the other two on either side thereof, each of them providing for generating a different beam of electromagnetic energy 20, each of the beams substantially aligned in elevation, as

illustrated in the side view of FIG. 32b, but in a different azimuthal direction, as illustrated in the top view of FIG. 32c.

The broadside feed antennas 18, 18' of the multi-element broadside feed array 12,

12' are operatively coupled with associated transmission lines 406, for example, microstrip or stripline feed lines, to associated transmitter or receiver circuitry 408 that provides for either generating a signal to be radiated by the broadside feed antennas 18, 18', receiving signals from broadside feed antennas 18, 18', or both generating and receiving signals to be radiated by or which are received by the broadside feed antennas 18, 18'. In FIGS. 32a-c and subsequent drawings hereinafter, each broadside feed antenna 18, 18' are illustrated schematically by a single first broadside antenna element 24.1, e.g. a first patch antenna element 102.1, and each associated transmission line 406 is illustrated by a single line. In the embodiments illustrated in FIGS. 32a-c and following, each broadside feed antenna 18, 18' may be either the first aspect of a broadside feed antenna 18 — for example, embodied by a first broadside antenna element 24.1 — operatively coupled to the transmitter or receiver circuitry 408 by a single transmission line 406, or by the second aspect of a broadside feed antenna 18', a plurality of broadside feed antenna elements 164 are operatively coupled to a common antenna feed 166 and associated power divider 168 by a plurality of corresponding feedlines 170, for example, as illustrated in FIGS. 25-29. For example, in accordance with the second aspect of a broadside feed antenna 18', the associated plurality of broadside feed antenna elements 164 may either be embodied by selected set of first broadside antenna elements 24.1 of the discrete lens array 14, or by a separate set of broadside feed antenna elements 164 that replace a subset of the first broadside antenna elements 24.1 of the discrete lens array 14. In the latter case, a set of broadside feed antenna elements 164 of a particular broadside feed antenna 18' need not necessarily conform to the spacing and arrangement of the remaining first broadside antenna elements 24.1 of the discrete lens array 14. For example, although the first broadside antenna elements 24.1 of the discrete lens array 14 are arranged in a rectangular grid, the elements thereof identified as broadside feed antennas 18, 18' could be embodied by separate sets of associated broadside feed antenna elements 164, for example, in a triangular pattern 174 of an associate three-element broadside feed antenna 172, or a square or rectangular pattern 198 of an associated four-element broadside feed antenna 172'. Furthermore, the plurality of broadside feed antenna elements 164 of a particular broadside feed antenna 18' would be fed by a corresponding plurality of feedlines 170,

wherein each associated transmission line 406 illustrated in FIG. 32a would then represent either the associated plurality of feedlines 170, or the associated plurality of feedlines 170 in combination with the associated common antenna feed 166.

The fourth aspect of a multi-beam antenna 400 provides for manufacturing the multi-element broadside feed array 12, 12' together with at least a portion of the discrete lens array 14 — for example, constructed as illustrated in FIGS. l-7a, 8, 10 or 13-24 — as a single circuit board assembly 410 usinfg a common first dielectric substrate 32. The fourth aspect of a multi-beam antenna 400 also provides for separate transmit and receive apertures, each either single- or multi-beam, and also provides for integrating the associated transceiver electronics 412 with the discrete lens array 14, for example, on the first dielectric substrate 32. For example, a multi-beam transmit antenna could be combined with either a simple patch array receive antenna with the patch array receive antenna having a fϊeld-of-view (FOV) substantially equal to that of the associated multi-beam transmit antenna, or with two receive patch arrays employing monopulse. In either case, the transceiver electronics 412 can be integrated with the multi-element broadside feed array 12, 12' and the discrete lens array 14 so as to provide for a complete assembly encompassing the entire millimeter wave structure that can be manufactured as a single circuit board assembly 410.

Accordingly, the fourth aspect of a multi-beam antenna 400 incorporates folded optics by locating the broadside feed antennas 18, 18' of the multi-element broadside feed array 12, 12' proximate to the center of the discrete lens array 14, which radiate electromagnetic energy 402.1 back onto a flat reflector 404, which in turn reflects the electromagnetic energy 402.2 towards the discrete lens array 14 for focusing. The broadside feed antennas 18, 18' are located on the rear side of the discrete lens array 14 and, in one embodiment, are operatively coupled to associated transceiver electronics 412 and an associated SPnT (single pole, multiple throw) switch network 414 by associated transmission lines 406, for example, microstrip or stripline feedlines located on either side of the associated first dielectric substrate 32 of the discrete lens array 14; but are not operatively coupled to corresponding associated broadside antenna elements 24.2 on the front side of the discrete lens array 14, so that a signal applied to a broadside feed antennas 18, 18' is radiated rearwards towards the reflector 404, but is not transmitted directly forwards through the discrete lens array 14. Since the wavefront traverses the distance between the discrete lens array 14 and the reflector 404 twice, in order to maintain the feed at the correct focal distance the space between the discrete lens array 14 and the

reflector 404 would be 111, which is half of the distance from the multi-element broadside feed array 12, 12' to the discrete lens array 14 in the standard arrangement where the multi-element broadside feed array 12, 12' directly illuminates the discrete lens array 14 from behind as was illustrated hereinabove in FIGS. 1-12. Because the broadside feed antennas 18, 18' are not operatively coupled to corresponding associated broadside antenna elements 24.2 on the front side of the discrete lens array 14, the broadside feed antennas 18, 18' present a blockage in the discrete lens array 14 that results in decreased gain, and increased sidelobe levels in comparison with the discrete lens array 14 illustrated in FIGS. 1-12.. This blockage can be substantial in embodiments configured for wide angle scanning for which the broadside feed antennas 18, 18' might extend from one edge of the discrete lens array 14 to the other. For example, for scanning from +22.5 degrees to -22.5 degrees for a discrete lens array 14 with f/D = 1, the multi-element broadside feed array 12, 12' to provide the associated 45 degree scan angle would have its phase center at approximately 0.5 D away from the center line of the discrete lens array 14, placing the outermost broadside feed antennas 18, 18' at the edge of the discrete lens array 14. If beams of electromagnetic energy 20 are created such that they overlap at the 3 dB points in their patterns throughout the scan range, then a swath extending across the entire discrete lens array 14 would no longer provide for beam focusing.

Referring to FIGS. 33a-c, in accordance with a fifth aspect of a multi-beam antenna 500, the limitation of blockage of the discrete lens array 14 by the multi-element broadside feed array 12, 12' integrated therewith in accordance with the fourth aspect of a multi-beam antenna 400, is mitigated by incorporating a polarized multi-element broadside feed array (12, 12')' and a polarization dependent discrete lens array 14'. In accordance with one embodiment, the first broadside antenna elements 24.1 of the discrete lens array 14' are arranged such that their geometric pattern on the first dielectric substrate

32 of the discrete lens array 14' provides for the broadside feed antennas 18, 18' of the multi-element broadside feed array (12, 12')' to be realized with a subset of the first broadside antenna elements 24.1 at the correct positions for the desired beam scan angles.

The discrete lens array 14' is adapted so as to provide for energy of a first polarization to pass between the first 24.1 and second 24.2 broadside antenna elements of the discrete lens array 14', for example, through the associated phase adjusting coupling slots 38 (or microstrip line vias) operatively coupling the first 24.1 and second 24.2 broadside antenna elements. Furthermore, the broadside feed antennas 18, 18' of the multi-element

broadside feed array 12, 12' are polarized in a direction that is orthogonal to that of the first polarization, so that electromagnetic energy provided to the broadside feed antennas 18, 18' is radiated therefrom, but not substantially simultaneously transmitted through the discrete lens array 14' to the corresponding second broadside antenna elements 24.2 operatively coupled therewith. The fifth aspect of the multi-beam antenna 500 further incorporates a polarization twist reflector 502 located about half of the focal length f of the discrete lens array 14 therefrom. In operation to generate one or more beams of electromagnetic energy 20, one or more corresponding signals from the transceiver electronics 412 are coupled to the associated broadside feed antennas 18, 18' of the multi-element broadside feed array 12, 12' using the first polarization, for example, in a first embodiment, vertical polarization (V). These broadside feed antennas 18, 18' also serve as first broadside antenna elements 24.1 of the discrete lens array 14', however these first broadside antenna elements 24.1 of the discrete lens array 14' are polarized, for example, in the first embodiment, horizontally polarized (H), so as to block the first polarized feed signals from transmission therethrough. However, the orthogonal polarization at the broadside feed antennas 18, 18', as well as at the remaining first broadside antenna elements 24.1 of the discrete lens array 14', is coupled through the discrete lens array 14' to the second broadside antenna elements 24.2 on the opposite side of the discrete lens array 14' and is focused thereby. The electromagnetic energy 402.1 at the first polarization is radiated rearwards from the broadside feed antennas 18, 18', and is reflected forwards with orthogonal polarization by the polarization twist reflector 502. Accordingly, the polarization of the electromagnetic energy 402.2 reflected by the polarization twist reflector 502 is orthogonally twisted, or rotated, relative to the polarization of the electromagnetic energy 402.1 incident thereupon, so as to be oriented for transmission through the discrete lens array 14'. Accordingly, the electromagnetic energy 402.2 reflected by the polarization twist reflector 502 is intercepted by the first broadside antenna elements 24.1 of the discrete lens array 14', including the broadside feed antennas 18, 18' of the multi-element broadside feed array 12, 12', and is coupled therethrough and focused without the loss of energy that would otherwise occur from blockage by the multi-element broadside feed array 12, 12',wherein the entire discrete lens array 14' can then be used to focus and transmit the associated electromagnetic energy 402.2.

Referring to FIGS. 34, 35a and 35b, there are illustrated several embodiments of broadside feed antennas 18/ first broadside antenna elements 24.1 that can provide for operation with dual polarization. Referring to FIG. 34, a rectangular patch broadside feed antenna 18/ first broadside antenna element 24.1 fed at a first location 504 would provide for radiation with an X-polarization, but would not be substantially coupled to the second location 506, which would be responsive to radiation having a Y-polarization.

Referring to FIGS. 35a and 35b, there is illustrated a circular patch broadside feed antenna 18/ first broadside antenna element 24.1' fed with a "slot-pin feed" in accordance with the technical paper by Yoshiyuki FUJINO, Masato TANAKA and Masaharu FUJITA, entitled "A New Feeding Method for Dual-Polarized Patch Antenna With Low Cross- Polarization Ratio", which is incorporated herein by reference. More particularly, the circular patch broadside feed antenna 18/ first broadside antenna element 24.1 is conductively fed with a pin-feed 508 at a first location 504 offset from the center along a diametrical X-axis of the circular patch broadside feed antenna 18/ first broadside antenna element 24.1, so as to provide for transmitting or receiving radiation with an X- polarization. The pin-feed 508 is coupled to a first microstrip line 510, having an open stub 512 to provide for impedance matching. The circular patch broadside feed antenna 18/ first broadside antenna element 24.1 is also fed by a Y-directed second microstrip line 514 that couples to the center of the broadside feed antenna 18/ first broadside antenna element 24.1 through a central slot 516 along the X-axis through a central conductive layer 518, so as to provide for transmitting or receiving radiation with a Y-polarization, wherein the broadside feed antenna 18/ first broadside antenna element 24.1 is separated from the central conductive layer 518 by a first dielectric substrate 520, and the central conductive layer 518 is separated from the first 510 and second 514 microstrip lines by a second dielectric substrate 522, the second microstrip line 514 is aligned with the Y-axis and extends under the circular patch broadside feed antenna 18/ first broadside antenna element 24.1 across the central slot 516, and the pin- feed 508 is insulated from the central conductive layer 518.

Referring to FIGS. 36a and 36b, there is illustrated an example of a polarization twist reflector 502 comprising a plurality of grooves 524 in a metallic plate or casting 526, wherein the grooves 524 are oriented at substantially 45 degrees to the direction of polarization of the incident and reflected electromagnetic energy, and are about a half wavelength deep, a quarter wavelength wide, and are substantially parallel to one another and

separated from one another by about a third of a wavelength. Alternatively, the polarization twist reflector 502 could be constructed using microstrip technology.

Referring to FIGS. 37 and 38, there are illustrated several examples of lens elements 110 adapted to provide for radiation without transmission at a first polarization, and transmission therethrough at a second polarization that is orthogonal to the first polarization, which, for example, may be used to provide for the first broadside antenna elements 24.1 of a broadside feed antenna 18, 18' of the fifth aspect of a multi-beam antenna 500. The embodiment illustrated in FIG. 37 is adapted from that illustrated in FIG. 19, wherein under transmission, a feed signal would be applied to the second location 126.2 on an edge of a first patch antenna element 102.1 so as to provide for generating linearly polarized electromagnetic energy 402.1 in the X-direction, which is radiated rearwards therefrom, but which is not simultaneously transmitted through the lens element 110 because a lack of a connection between the first 102.1 and second 102.2 patch antenna elements for that polarization. However, the orthogonally polarized electromagnetic energy 402.2 reflected from the polarization twist reflector 502 is polarized in the Y-direction, and is conducted through the lens element 110 via the first delay line 128.1 and associated first conductive via 132.1. Similarly, under reception, electromagnetic energy received by the second patch antenna element 102.2 and transmitted though the lens element 110 is radiated backwards from the first patch antenna element 102.1 with a polarization in the Y-direction, which becomes rotated by the polarization twist reflector 502 so as to provide for electromagnetic energy polarized in the X-direction and incident upon the first patch antenna element 102.1, so as to provide for generating a received signal at the feed at the second location 126.2 on the edge of the first patch antenna element 102.1.

The embodiment illustrated in FIG. 38 is adapted from that illustrated in FIGS. 1-6, wherein the associated first patch antenna element 26.1 is illustrated as being longer in the cross-polarization direction so as to provide for improved reflection therefrom, wherein the associated feed is coupled to an end of the first patch antenna element 26.1 so as to provide for generating linearly polarized electromagnetic energy 402.1 in the X-direction, which is radiated rearwards therefrom, but which is not simultaneously transmitted through the lens element 110 because a weak coupling between the first 102.1 and second 102.2 patch antenna elements for that polarization. However, the orthogonally polarized electromagnetic energy 402.2 reflected from the polarization twist reflector 502 is polarized in the Y-direction, and is coupled through the lens element 110 via the associated

coupling slot 38. Similarly, under reception, electromagnetic energy received by the second patch antenna element 102.2 and coupled though the lens element 110 is radiated backwards from the first patch antenna element 102.1 with a polarization in the Y- direction, which becomes rotated by the polarization twist reflector 502 so as to provide for electromagnetic energy polarized in the X-direction and incident upon the first patch antenna element 102.1, so as to provide for generating a received signal at the feed at the edge of the first patch antenna element 102.1.

Referring to FIGS. 39a-c, there is illustrated a sixth aspect of a multi-beam antenna

600 that provides for generating one or more relatively narrow, relatively high gain antenna beams in a forward direction, and for generating one or more relatively wider, relatively lower gain antenna beams toward one or more sides of the forward direction, which can be beneficial in automotive radar systems, so as to provide for sensing objects in the forward direction moving at relatively higher relative velocities within a relatively longer range, as would be suitable for autonomous cruise control (ACC) applications, while also providing for sensing objects within a relatively shorter range at angles away from the forward direction, as would be suitable for sensing relatively lower relative velocity situations such as crossing traffic and vehicles cutting in front of the host vehicle with the radar system, so as to provide for multiple functions, such as Automatic Cruse Control (ACC), Stop and Go ACC, and wide field-of-view (FOV) pre-crash warning/mitigation, using a single radar sensor. As with the fourth aspect of a multi-beam antenna 400 illustrated in FIGS. 32a-c, the sixth aspect of a multi-beam antenna 600 incorporates a plurality of broadside feed antennas 18, 18' on an associated discrete lens array 14" along a scan direction 602, wherein the broadside feed antennas 18, 18' are adapted to radiate electromagnetic energy 402.1 backwards away from the discrete lens array 14 towards a reflector 404 located at about half of the focal length f of the discrete lens array 14 therefrom, which then reflects the electromagnetic energy 402.2 forwards towards the discrete lens array 14. As with the fourth aspect of a multi-beam antenna 400, the discrete lens array 14" is adapted so that the electromagnetic energy applied to the broadside feed antennas 18, 18' is not simultaneously transmitted through the discrete lens array 14". The broadside feed antennas 18, 18' are adapted so that the broadside feed antennas 604 (18, 18'), for example, feed patches, proximate to the center of a discrete lens array 14" are configured to radiate with a first polarization, for example, vertical polarization (V), while the broadside feed antennas 606 (18, 18') positioned relatively

farther away from the center of the discrete lens array 14" along the scan direction 602 are configured to radiate with a relatively orthogonal second polarization, for example, horizontalpolarization. For example, as described hereinabove, the polarization transmitted or received from a square patch radiator is determined by the geometry of the associated feed point relative to the square patch radiator. In accordance with the sixth aspect of a multi- beam antenna 600, the discrete lens array 14" is adapted so that the attenuation of the associated lens elements 110 as a function of distance from the center of the discrete lens array 14" along the scan direction 602 is dependent upon polarization, so as to make the effective aperture size of the discrete lens array 14" along the scan direction 602 different for different polarizations, wherein a relatively larger aperture provides for forming a relatively narrower beam of electromagnetic energy 20 while a relatively smaller aperture provides for forming a relatively wider beam of electromagnetic energy 20.

More particularly, for the above example, each of the lens elements 110 over the entire aperture of the discrete lens array 14" provide for coupling vertically polarized (V) electromagnetic energy through the discrete lens array 14" without any additional attenuation, whereas for horizontally polarized (H) electromagnetic energy, the lens elements 110 are adapted to attenuate the transmission of horizontally polarized (H) electromagnetic energy therethrough, wherein the amount of attenuation either increases with distance from the center of the discrete lens array 14" along the scan direction 602, or is increased for distances from the center of the discrete lens array 14" along the scan direction 602 that are greater than a threshold. Accordingly, a beam of electromagnetic energy 20 formed from electromagnetic energy generated by a vertically polarized (V) broadside feed antenna 604 (18, 18') relatively proximate to the center of the discrete lens array 14", using the entire aperture of the discrete lens array 14", would be relatively narrower along the scan direction 602, and at a relatively higher gain, than would a corresponding beam of electromagnetic energy 20 formed from electromagnetic energy generated by a horizontally polarized (H) broadside feed antenna 606 (18, 18') relatively farther from the center of the discrete lens array 14", using a relatively smaller effective aperture, which would be relatively wider along the scan direction 602, and at a relatively lower gain, wherein the horizontally polarized (H) broadside feed antenna 606 (18, 18') relatively farther from the center of the discrete lens array 14" along the scan direction 602 provide for generating a corresponding beam of electromagnetic energy 20 at a relatively larger scan angle relative to the center of the discrete lens array 14". Alternatively, the relative width of a

horizontally polarized (H) beam of electromagnetic energy 20 could be adapted by changing the size of the associated horizontally polarized (H) broadside feed antenna 606 (18, 18'), or associated array.

In the embodiment illustrated in FIG. 39b, the attenuation of the discrete lens array 14" is not tapered in the direction orthogonal to the scan direction 602, i.e. in the vertical direction, so that in that direction, the associated beamwidth 608 of a horizontally polarized (H) beam of electromagnetic energy 20 is substantially the same as that of a vertically polarized (V) beam of electromagnetic energy 20. Furthermore, in view of the relatively wider beamwidths of the horizontally polarized (H) beams of electromagnetic energy 20 along the scan direction 602, relative to those of the corresponding vertically polarized (V) beams of electromagnetic energy 20, for the same level of overlap of adjacent beams of electromagnetic energy 20, the corresponding associated broadside feed antennas 606 (18, 18') can be further separated from one another than would be the broadside feed antennas 604 (18, 18') associated with the vertically polarized beams of electromagnetic energy 20, as is illustrated in FIGS. 39a and 39c.

As with the fourth aspect of the multi-beam antenna 400, the performance of the sixth aspect of the multi-beam antenna 600 is degraded by aperture blockage, although the effects of this blockage may be mitigated by coupling the cross-polarization of the broadside feed antennas 18, 18' and using a polarization twist reflector 502 — as with the fifth aspect of the multi-beam antenna 500 — and appropriately swapping the polarization of lens elements 110 that with relatively substantial amplitude tapering, this blockage could be restricted to only those areas where the broadside feed antennas 18, 18' of the cross- polarization are located. Furthermore, the efficiency of the sixth aspect of the multi-beam antenna 600 is degraded for horizontally polarized (H) beams of electromagnetic energy 20 because of the relatively increased attenuation, and associated energy loss, by the discrete lens array 14" at relatively distal portions of the discrete lens array 14" in the scan direction 602.

Referring to FIGS. 40a-c, there is illustrated a seventh aspect of a multi-beam antenna 700, which is similar to the sixth aspect of the multi-beam antenna 600 illustrated in FIGS. 39a-c, except that instead of incorporating a uniform reflector 404, the seventh aspect of the multi-beam antenna 700 incorporates a polarization dependent reflect array 702, so as to provide for improved operating efficiency relative to the sixth aspect of the multi-beam antenna 600. The reflect array 702 is adapted to act substantially as a simple

reflector for electromagnetic energy 402.1 of a first polarization, for example, vertical polarization (V), and to provide for focusing electromagnetic energy 402.1 of a second polarization that is relatively orthogonal to the first, for example, horizontal polarization (H), wherein the reflect array 702 provides for focusing the electromagnetic energy 402.1 of the second polarization on a relatively central portion of the discrete lens array 14" so that the electromagnetic energy 402.2 incident upon the discrete lens array 14" is effectively limited by an aperture that is effectively smaller than the overall size of the discrete lens array 14", with the benefit of improved efficiency relative to the sixth aspect of the multi- beam antenna 600 because of refocused electromagnetic energy 402.2 that would otherwise be attenuated at the relatively distal portions of the discrete lens array 14" in the scan direction 602. The reflect array 702 and the discrete lens array 14" are adapted so that electromagnetic energy 402.2 of either polarization utilizes the full aperture of the discrete lens array 14" in a direction, e.g. vertical, that is orthogonal to the scan direction 602, so that in that orthogonal direction, the associated beamwidth 608 of the horizontally polarized (H) beam of electromagnetic energy 20 is substantially the same as that of the vertically polarized (V) beam of electromagnetic energy 20. Accordingly, the reflect array 702 is adapted to effectively act as a vertically oriented concave cylindrical reflector for the second, e.g. horizontal (H), polarization, and as a flat reflector for the first, e.g. vertical (V), polarization. Alternatively, the reflect array 702 could provide for uniform focusing of both polarizations in the direction, e.g. vertical, that is orthogonal to the scan direction 602. With effective focusing of the electromagnetic energy 402.2 by the reflect array 702, it may be possible in an alternative embodiment to replace the amplitude tapered discrete lens array 14", with a uniform discrete lens array 14 without amplitude tapering.

The reflect array 702 comprises a plurality of electromagnetically imaged lens elements 110' on a common conductive surface 704 that provides for the associated electromagnetic imaging. Each lens element 110' comprises a patch antenna element and a delay element, wherein the patch antenna element is separated from the conductive surface

704 by at least one dielectric layer, and the delay periods of the delay elements of different lens element 110' are adapted with respect to the location of the lens element 110' within the reflect array 702 so as to provide for focusing, wherein the delay element is coupled to the patch antenna element so as to provide for transmission of substantially only electromagnetic energy 402.1 of the second, e.g. horizontal (H), polarization through the delay element, whereas electromagnetic energy 402.1 of the first, e.g. vertical (H),

polarization is reflected by the patch element or the associated conductive surface. One example of a reflect array 702 is described in paragraphs [0063] and [0064] and FIGS. 25 and 26 of U.S. Patent Application Publication No. US 2006/0028386, the publication of U.S. Application Serial No. 11/161,681, both of which are incorporated herein by reference. As other examples, the lens element 110' could be formed by forming electromagnetic images of any of the embodiments illustrated in FIGS. 3, 13, 17, 19, 21, or 24a herein. For example, a lens element 110' based upon the embodiment illustrated in FIG. 3 would incorporated elements 24.2, 28, 34, 36 and 32 above the conductive surface 704; a lens element 110' based upon the embodiment illustrated in FIG. 17 would incorporated elements 102.1, 114.1, 118 and 112.1 above the conductive surface 704, with the conductive via 118 connected to the conductive surface 704; a lens element 110' based upon the embodiment illustrated in FIG. 19 would incorporated elements 102.1, 128.1, 132.1 and 134.1 above the conductive surface 704, with the first conductive via 132.1 connected to the conductive surface 704, and for focusing both polarizations, would also incorporate elements 128.3 and 132.2, with the second conductive via 132.2 connected to the conductive surface 704; a lens element 110' based upon the embodiment illustrated in FIG. 21 would incorporated elements 102.1, 138.1, 136, 140, 138.3 and 142 above the conductive surface 704, with the third conductive via 138.3 connected to the conductive surface 704; and a lens element 110' based upon the embodiment illustrated in FIG. 24a would incorporated elements 102.1, 154.1, 156, 152, 154.2 and 160 above the conductive surface 704, with the second conductive via 154.2 connected to the conductive surface 704.

Referring to FIGS. 41a-c, there is illustrated an eighth aspect of a multi-beam antenna 800, which is similar to the sixth aspect of the multi-beam antenna 600 illustrated in FIGS. 39a-c, except for a modified discrete lens array 14'" and the addition of a vertical polarizer 802 between the discrete lens array 14'" and the reflector 404. The discrete lens array 14'" is adapted so as to provide for a first focal length fy for vertically polarized (V) electromagnetic energy 402.2, and so as to provide for a second focal length fπ for horizontally polarized (H) electromagnetic energy 402.2. For example, the associated lens elements 110 of the discrete lens array 14'" may be constructed in accordance with the second embodiment of a lens element 110 ^π as illustrated in FIG. 19, wherein the scheduling of the lengths of the associate first 128.1 and second 128.2 delay lines as a function of location on the discrete lens array 14'" for a first polarization is different from the scheduling of the lengths of the associate third 128.3 and fourth 128.4 delay lines as a

function of location on the discrete lens array 14'" for a second polarization that is orthogonal to the first, so that the effective curvature of the discrete lens array 14'" for the first polarization is different from the effective curvature of the discrete lens array 14'" for the second polarization. More particularly, the discrete lens array 14'" is adapted so that the first focal length fy is greater than the second focal length fπ so as to provide for locating the vertical polarizer 802 between the discrete lens array 14'" and the reflector 404. The vertical polarizer 802 provides for reflecting horizontally polarized (H) electromagnetic energy 402.1 incident thereupon, and the location of the vertical polarizer 802 and the value of the second focal length f _H of the discrete lens array 14'" is adapted so that the path length of the resulting reflected horizontally polarized (H) electromagnetic energy 402.2' from the associated broadside feed antennas 606 (18, 18') to the discrete lens array 14"' is nominally equal to the second focal length fπ of the discrete lens array 14'". Vertically polarized (V) electromagnetic energy 402.1 incident upon the vertical polarizer 802 is transmitted therethrough, and the path length of the resulting reflected vertically polarized (V) electromagnetic energy 402.2 from the reflector 404 is nominally equal to the first focal length f _v of the discrete lens array 14'". The relatively shorter second focal length fH of the discrete lens array 14'" provides for forming an associated horizontally polarized (H) beam of electromagnetic energy 20 having an associated beamwidth that is relatively broader than the corresponding beamwidth of an associated vertically polarized (V) beam of electromagnetic energy 20 which is formed using the relatively longer first focal length f _v , wherein the ratio of the beamwidth of the horizontally polarized (H) beam of electromagnetic energy 20 to that of the vertically polarized (V) beam of electromagnetic energy 20 is inversely proportional to the ratio of the second focal length fπ to the first focal length f _v . The relatively shorter effective path length of the horizontally polarized (H) electromagnetic energy 402.2' from the broadside feed antennas 606 (18, 18') to the discrete lens array 14'", relative to that of the vertically polarized (V) electromagnetic energy 402.2 from the broadside feed antennas 604 (18, 18') to the discrete lens array 14'", provides for the spot size of the horizontally polarized (H) electromagnetic energy 402.2' incident upon the discrete lens array 14'" to be relatively smaller than the spot size of the vertically polarized (V) electromagnetic energy 402.2 incident upon the discrete lens array 14'", wherein the ratio of the respective associated spot sizes is proportional to the ratio fii/fv of the corresponding focal lengths fπ, fv, which further provides for a relatively

wider beamwidth of the resulting horizontally polarized (H) beam of electromagnetic energy 20 relative to that of the vertically polarized (V) beam of electromagnetic energy 20.

The discrete lens array 14'" may be adapted either with or without the amplitude tapering of the discrete lens array 14" in accordance with the sixth aspect of a multi-beam antenna 600, wherein the relatively shorter effective path length of the horizontally polarized

(H) electromagnetic energy 402.2' provides for illuminating a relatively smaller area of the discrete lens array 14'", thereby possibly precluding the need for amplitude tapering. In yet another alternative embodiment, a reflect array 702 may be used instead of the reflector 404 so as to provide for additional focusing of the vertically polarized (V) electromagnetic energy 402.2. In this case, the design of a reflect array 702, if used, would be simplified because it would only need to be accomodate one polarization.

Referring to FIG. 42, a first embodiment of a vertical polarizer 802.1 comprises parallel conductors 804 spaced from one another by about an eighth wavelength, the openings being aligned in the direction 806 of E-field transmission, i.e., the direction of polarization. Referring to FIGS. 43a and 43b a second embodiment of a vertical polarizer 802.2 comprises parallel slots 808 in a conductive plate 810, for example, a metal plate or casting, the slots 808 being aligned in the direction 806 of E-field transmission, the slots 808 being spaced from one another by about a half wavelength, wherein the remaining conductive strips 812 between adjacent slots 808 are about one eighth wavelength wide and a half wavelength deep.

It should be noted that in various polarization-dependent embodiments described herein, the horizontal (H) and vertical (V) polarizations can be interchanged with no effect. Furthermore, these embodiments are not necessarily limited to linear polarizations, but could alternatively be adapted to instead utilize circular polarizations, with right- and left- hand circular polarization being substituted for vertical and horizontal polarization, respectively, or horizontal and vertical polarization, respectively, or vice versa.

Referring to FIGS. 44a-c, there is illustrated a ninth aspect of a multi-beam antenna 900 incorporating a polarization dependent discrete lens array 14"" that cooperates with a polarized multi-element broadside feed array (12, 12')" located about a third of a focal length f of the discrete lens array 14"" therefrom, together with a polarization twist reflector 502 that is substantially co-planar with the polarized multi-

element broadside feed array (12, 12')". The discrete lens array 14"" is adapted to transmit a first polarization, for example, a vertical polarization (V), and to reflect a second polarization, for example, a horizontal polarization (H). For example, the first 24.1 and second 24.2 broadside antenna elements, e.g. first 102.1 and second 102.2 patch antenna elements, are interconnected or coupled together with a delay element 30 such electromagnetic energy 402.1, 402.2 of the first polarization is coupled from the first broadside antenna element 24.1 through the delay element 30 to the second broadside antenna element 24.2, whereas electromagnetic energy 402.1, 402.2 of the second polarization is not, for each of the lens element 110 of the discrete lens array 14"", for example, as determined by the location on the first broadside antenna element 24.1 where the delay element 30 is coupled for a conductive connection, or the orientation of an associated coupling slot 38 of the delay element 30 for coupling by an electromagnetic field. The polarized multi-element broadside feed array (12, 12')" comprises a first set of broadside feed antennas 606 (18, 18') for example, feed patches, on a substrate 902 adapted to radiate a first polarization, for example, horizontal polarization (H), towards the discrete lens array 14"", and located proximate to a central axis 904 of the discrete lens array 14"". The polarized multi-element broadside feed array (12, 12')" further comprises a second set of broadside feed antennas 604 (18, 18') on the substrate 902, positioned relatively farther away from the central axis 904 of the discrete lens array 14" along a scan direction 602, and adapted to radiate a second polarization, for example, vertical polarization (V). The substrate 902 is located behind the discrete lens array 14"" and in cooperation with the polarization twist reflector 502 so that the associated broadside feed antennas 604, 606 (18, 18') are surrounded thereby with windows in the polarization twist reflector 502, so as to enable the associated broadside feed antennas 604, 606 (18, 18') to radiate therethrough towards the discrete lens array 14"".

Accordingly, horizontally polarized (H) electromagnetic energy 402.1 radiated by the first set of broadside feed antennas 606 (18, 18') is reflected by the discrete lens array 14"" back towards the polarization twist reflector 502, which rotates the polarization thereof, so that the resulting electromagnetic energy 402.2 reflected thereby towards the discrete lens array 14"" becomes vertically polarized (V) and thereafter transmitted through the discrete lens array 14"" and transformed thereby into one or more associated beams of electromagnetic energy 20. Vertically polarized (V) electromagnetic energy 402.1 radiated by the second set of broadside feed antennas 604 (18, 18') is transmitted

through the discrete lens array 14"" without reflection and transformed thereby into one or more associated beams of electromagnetic energy 20. Accordingly the electromagnetic energy 402.1 from relatively near-axis first set of broadside feed antennas 606 (18, 18') is reflected twice and travels about one focal length f of the discrete lens array 14"" before being transmitted therethrough, whereas the electromagnetic energy 402.1 from relatively off-axis second set of broadside feed antennas 604 (18, 18') is not reflected, but instead travels about one third of a focal length f of the discrete lens array 14"" before being transmitted therethrough. Accordingly, the electromagnetic energy 402.1 from relatively off-axis second set of broadside feed antennas 604 (18, 18') illuminates the discrete lens array 14"" with a spot size having an area about one ninth that of the spot size of the electromagnetic energy 402.1 from relatively on-axis second set of broadside feed antennas 606 (18, 18'), so that a beam of electromagnetic energy 20 from the relatively off-axis second set of broadside feed antennas 604 (18, 18') would be about three times wider the a beam of electromagnetic energy 20 from the relatively near-axis first set of broadside feed antennas 606 (18, 18').

While specific embodiments have been described in detail in the foregoing detailed description and illustrated in the accompanying drawings, those with ordinary skill in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the any claims which are derivable from the description herein, and any and all equivalents thereof.

What is claimed is: