FIELD OF INVENTION

The present invention generally relates to the field of radio communication technology and, more particularly, to electronically beam steerable antenna devices. The present invention may be used for providing high data rate point-to-point millimeter-wave communications in radio relay station applications.

RELATED ART

Radio relay stations provide a high data rate point-to-point millimeter-wave communication at distances of about several kilometers in line-of-sight conditions. At the present time, radio relay stations use various radio frequency ranges with a carrier frequency in the range of 10 to 100 GHz. The increase of carrier frequency is associated with constantly growing demands for higher communication system throughput. The communication system throughput can be increased using a wider frequency bandwidth so as to transmit a signal at a higher carrier frequency.

However, increase of a carrier frequency results in greater signal propagation losses. Aperture antennas having a size significantly larger than an operating wavelength and, consequently, a high directivity can be used to compensate such propagation losses. Aperture antennas include various reflector antennas, horn antennas, and lens antennas. These antennas comprise a primary antenna element emitting a signal and a secondary device having a large size and creating a highly directive radiation pattern. Various reflective mirror systems, dielectric lenses as well as combinations of mirrors and lenses can be used as such secondary device.

The use of antennas with highly directive radiation pattern is associated with problems related to adjustment and a possibility of communication failure even at slight orientation changes of a radio relay station. Aperture beam scanning antennas can be used to provide quick automatic adjustment of the beam direction in a small angle range which is equal to several radiation pattern beamwidths without employing specially instructed personnel.

Electronically beam steerable mirror antenna devices are known in the prior art. Two-mirror Cassegrain antennas are a widely used type of mirror antenna devices which can provide electronic beam steering.

For example, US 7,834,803 discloses a Cassegrain scanning antenna configuration comprising a Cassegrain antenna and switchable horn antennas serving as primary antenna elements. In particular, such configuration provides electronic beam steering in various radar applications.

However, the use of horn antennas as primary antenna elements involves high costs. In addition, horn antennas have a large size and can not be configured so as to provide beam overlapping at an acceptable level, e.g. the level corresponding to a half power beamwidth, while all other parameters are practically efficient. Thus, the configuration disclosed in US 7,834,803 does not provide electronic beam steering in continuous angle sector while maintaining a stable signal transmission in a radio relay station.

Another type of an antenna device which provides electronic beam steering is a lens antenna. International application WO 2004051803 discloses a lens antenna with offset primary antenna elements. The beam scanning in this antenna is carried out using an array of switched primary antenna elements, each primary antenna element being located at a different distance from the focus perpendicularly to a lens axis. However, this antenna is not suitable for employing planar technologies for manufacturing primary antenna elements and providing beam scanning in a continuous manner with respect to an angle. Another disadvantage of this antenna is a large axial dimension.

US 7,688,263 and US 7,667,665 disclose electronically beam steerable Luneberg lenses having a spherical shape. These lenses are made of a heterogeneous dielectric and have a refractive index which depends on a radius. However, in order to provide beam scanning in these antennas, primary antenna elements are disposed on an outer spherical surface of a lens which makes it impossible to use a cheap planar technology suitable for a mass production.

Known are integrated lens antennas allowing for solving the aforementioned problems of other electronically beam steerable antennas, particularly eliminating high costs due to difficulties of implementing planar technologies suitable for a mass production. In integrated lens antennas, switchable planar antenna elements are directly integrated on a flat lens surface.

US 7,683,844 discloses an integrated lens antenna which can be considered as the closest prior art for the present invention. The electronically beam steerable antenna device disclosed in this patent comprises a plurality of primary antenna elements and transmission lines, a switching network adapted to apply electric power to at least one primary antenna element, wherein the plurality of primary antenna elements, transmission lines and the switching network are formed on a semiconductor die (see fig. 1 ). A transceiver and the plurality of primary antenna elements are electrically connected by means of wire bond connections and are integrated on a flat surface of a hemispherical dielectric lens having a cylindrical extension. This antenna device may be used in millimeter-wave receivers, transmitters and transceivers allowing for switching between receiving and transmitting modes.

However, a disadvantage of the above antenna device is low antenna radiation efficiency (less than 15%) and high signal losses associated with the fact that the plurality of primary antenna elements is formed on a semiconductor die.

Accordingly, there is a necessity to provide at low costs an electronically beam steerable antenna device which allows for electronic beam steering in a continuous angle sector while increasing radiation efficiency and reducing signal losses.

DISCLOSURE OF INVENTION

The object of the present invention is to provide at low costs an electronically beam steerable antenna device which allows for electronic beam steering in a continuous angle sector while increasing radiation efficiency and reducing signal losses.

The object set above is attained by providing an electronically beam steerable antenna device comprising a plurality of primary antenna elements and transmission lines, a switching network adapted to apply electric power to at least one primary antenna element, the plurality of primary antenna elements and transmission lines are formed on a high frequency dielectric board and the switching network is electrically connected to the said high frequency dielectric board.

Accordingly, the object set above is attained by using a high frequency dielectric board (with significantly smaller losses than semiconductor die) on which the plurality of primary antenna elements and transmission lines are formed and to which the switching network is electrically connected.

The electronically beam steerable antenna device can further comprise a transceiver which is electrically connected to the high frequency dielectric board.

According to one embodiment, the transceiver and the switching network are formed on semiconductor integrated circuits which are electrically connected to the high frequency dielectric board by means of wire bond connections. The switching network can comprise at least one 1 *N switch formed on the semiconductor integrated circuits, wherein N>2. Additionally, each switch can be formed on a separate semiconductor integrated circuit.

According to another embodiment, the transceiver and the switching network are installed into blind cavities made in the high frequency dielectric board. According to still another embodiment, the transceiver and the switching network are formed on semiconductor integrated circuits which are electrically connected to the high frequency dielectric board by means of a flip-chip technology.

The high frequency dielectric board can be made of high temperature co-fired ceramics or low temperature co-fired ceramics. According to yet another embodiment, the high frequency dielectric board comprises a printed circuit board.

According to yet another embodiment, the switching network is formed on semiconductor integrated circuits and the transceiver is formed by means of waveguide elements and is electrically connected to the high frequency dielectric board by means of a waveguide to microstrip transition.

According to yet another embodiment, the present antenna device additionally comprises another switching network and the plurality of primary antenna elements comprises two arrays of primary antenna elements, wherein the first array is adapted to transmit a signal having a first linear polarization, the second array is adapted to receive a signal having a second linear polarization, orthogonal to the first linear polarization, and each switching network is adapted to independently control one of the arrays of primary antenna elements.

According to yet another embodiment, the present antenna device further comprises another switching network, each primary antenna element is adapted to transmit a signal having a first linear polarization and to receive a signal having a second linear polarization, orthogonal to the first linear polarization, and each switching network is adapted to independently control the plurality of primary antenna elements while transmitting a signal having the first linear polarization and receiving a signal having the second linear polarization, respectively. In this case, microstrip dual polarization antenna elements can be used as the primary antenna elements.

According to yet another embodiment, the primary antenna elements are microstrip antenna elements.

The antenna device according to the present invention can additionally comprise a dielectric lens forming a narrow beam and providing a beam deviation while scanning. In this case, the plurality of primary antenna elements and transmission lines are integrated on a flat surface of the dielectric lens. The dielectric lens shape can be selected from the group comprising hemiellipsoidal shape with a cylindrical extension, hemispherical shape with a cylindrical extension, hemiellipsoidal shape with a truncated cone extension, and a shape of an ellipsoid truncated with a plane extending perpendicularly to an axis of the ellipsoid in proximity of a focus of the ellipsoid. According to yet another embodiment, the presented antenna device is adapted to provide high data rate point-to-point millimeter-wave wireless communications for a radio relay station and to adjust a beam in case of initial adjustment or slight changes of orientation of a radio relay station due to such external effects as wind, vibrations, compression and/or extension of portions of the supporting structure with the temperature changes etc.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be described in further detail with references being made to the accompanying drawings, wherein:

FIG. 1 illustrates a prior art electronically beam steerable antenna device;

FIG. 2 shows example axial sections of one embodiment of the present integrated lens antenna according to various relative arrangements of a transceiver and a switching network: FIG. 2a corresponds to an embodiment wherein the dielectric board is provided with blind cavities, FIG. 2b and 2c correspond to an embodiment wherein a flip-chip mounting technology is used, wherein in FIG. 2c semiconductor integrated circuits are arranged on the side of the dielectric lens;

FIG. 3 shows an axial section of the present integrated lens antenna according to an embodiment wherein the transceiver is formed by means of waveguide elements and electrically connected to the high frequency dielectric board by means of a waveguide to microstrip transition;

FIG. 4 illustrates an embodiment with separate receiving and transmitting functions, wherein FIG. 4a depicts an example configuration including two independent arrays of primary antenna elements, and FIG. 4b depicts an example configuration including one array of primary antenna elements with two independent inputs each;

FIG. 5 illustrates examples of switching networks for 16 primary antenna elements, wherein in the embodiments in FIG. 5a switches of 1 ><2 type are used, and in FIG. 5b switches of 1 *4 type are used;

FIG. 6 illustrates hemiellipsoidal and hemispherical shapes of a dielectric lens having a cylindrical extension;

FIG. 7 illustrates a hemispherical shape of a dielectric lens having a truncated cone extension used in the present lens antenna;

FIG. 8 illustrates an embodiment with microstrip antenna configuration used as a primary antenna element;

FIG. 9 illustrates an embodiment with dual polarization microstrip antenna configuration used as a primary antenna element; DETAILED DESCRIPTION OF THE INVENTION

AND PREFERRED EMBODIMENTS THEREOF

The present invention will be more fully understood from the description of the embodiments of realization of an electronically beam steerable integrated lens antenna for high data rate point-to-point millimeter-wave communications in radio relay station applications.

FIG. 2 shows axial sections of various embodiments of the integrated lens antenna according to the present invention. In one embodiment, the integrated lens antenna comprises a homogeneous dielectric lens 1 , primary antenna elements 4 and transmission lines for connecting thereof (not shown), a switching network 3 adapted to apply electric power to at least one primary antenna element, and a transceiver 2. Switching network 3 and transceiver 2 are formed on semiconductor integrated circuits. Primary antenna elements 4 and transmission lines are formed on high frequency dielectric board 5 and integrated on a flat surface of homogeneous dielectric lens 1 . A multilayer printed or ceramic board can be used as a high frequency dielectric board 5.

FIG. 2 illustrates various relative arrangements of transceiver 2 and switching network 3 on dielectric board 5. According to an embodiment illustrated in FIG. 2a, dielectric board 5 has blind cavities for switching network 3 and transceiver 2 mounting. Switching network 3 and transceiver 2 are electrically connected to the transmission lines by means of wire bond connections 6. According to another embodiment illustrated in FIG. 2b, transceiver 2 and switching network 3 are electrically connected to dielectric board 5 by means of flip-chip connections 7. According to still another embodiment illustrated in FIG. 2c, transceiver 2 and switching network 3 are electrically connected to dielectric board 5 by means of flip-chip connections 7 on the side of lens 1 . According to this embodiment, lens 1 has special cut-outs for transceiver 2 and switching network 3. Such configuration can be used even in case of a one-layer dielectric board 5 made of high temperature co-fired ceramics, for example. In addition, such configuration requires minimizing leakage radiation from transceiver 2 and switching network 3 as well as the points of their connections to dielectric board 5 into the body of lens 1 , for example by covering an inner surface of the cut-outs with metal.

In millimeter-wave radio relay stations, a transceiver is sometimes formed by means of waveguide elements in view of yet limited accessibility of efficient technologies for manufacturing semiconductor integrated circuits having characteristics required for a millimeter-wave range. FIG. 3 shows an axial section of the lens antenna according to the embodiment wherein a transceiver 8 is formed by means of waveguide elements and electrically connected to the board 5 by means of waveguide 9 and waveguide to microstrip transition 10. Switching network 3 can be arranged on dielectric board 5 according to one of the configurations illustrated in FIG. 2.

FIG. 4 illustrates an embodiment with separate signal receiving and transmitting functions. According to an embodiment illustrated in FIG. 4a, the present integrated lens antenna comprises two arrays of antenna elements 13 integrated on lens 1 . One of the arrays is adapted to transmit a signal having a first linear polarization, and another array is adapted to receive a signal having a second linear polarization, orthogonal to the first linear polarization. According to this embodiment, the integrated lens antenna comprises two switching networks. Each switching network is adapted to independently control one of the arrays of primary antenna elements.

According to another embodiment illustrated in FIG. 4b, each primary antenna element 13 is adapted to transmit a signal having a first linear polarization and to receive a signal having a second linear polarization, orthogonal to the first linear polarization. According to this embodiment, the integrated lens antenna comprises two switching networks. Each switching network is adapted to independently control the primary antenna elements while transmitting a signal having the first linear polarization and receiving a signal having the second linear polarization, respectively.

According to one embodiment, the switching network comprises at least one 1 x N switch formed on the semiconductor integrated circuits, wherein N≥2. FIG. 5 illustrates example switching networks for 6 primary antenna elements, wherein FIG. 5a illustrates a case of using switches of 1 *2 type, and Fig. 5b illustrates a case of using switches of 1 *4 type. Each switch can be formed on a separate semiconductor integrated circuit.

FIG. 6 illustrates hemiellipsoidal and hemispherical shapes of dielectric lens 1 having a cylindrical extension. The length of the cylindrical extension can be set on the basis of the analysis of final characteristics of the antenna according to the present invention with a particular primary antenna element. The main requirement for the material of the dielectric lens according to the present invention is ability to provide a low level of dielectric losses.

According to another embodiment, the lens weight is reduced by truncating a lens portion which does not positively contribute to the directivity of the lens antenna. FIG. 7 illustrates a corresponding hemispherical shape of the dielectric lens having a truncated cone extension. The weight reduction is important for large antennas used in radio relay stations.

FIG. 8 illustrates a microstrip antenna configuration used as a primary antenna element in the lens antenna according to the present invention. According to the illustrated configuration, the electromagnetic coupling occurs through the slot aperture in the ground plane.

According to yet another embodiment illustrated in FIG. 9, a dual polarization microstrip antenna element is used as a primary antenna element. The dual polarization is achieved by means of two feed points through via holes 91 for direct signal inputting.

Various dipoles, slot antennas etc. may be also used as planar primary antenna elements for integrated lens antennas. However, in case of small dielectric permittivity antenna elements having the major portion of the radiation concentrated in one half- space, i.e. half-space on the side of the lens, are preferable. Particularly, such antenna elements include the above described microstrip antenna elements having different techniques for signal inputting, wherein the presence of a large ground plane ensures a radiation pattern concentrated in the half-space on the side of the lens.

As it is shown in FIG. 2, for example, when electric power is applied to one of primary antenna elements 4 each displaced with respect to the central axis of lens 1 a radiation pattern having a beam deviation in a specific direction is formed. In case of initial adjustment or slight orientation changes of a radio relay station due to such external effects as wind, vibrations, compression and/or extension of portions of the supporting structure, the narrow beam direction can be corrected by switching primary antenna elements 4 with the help of switching network 3. Primary antenna elements 4 having a small size can be configured so as to provide beam overlapping at an acceptable level, e.g. the level corresponding to a half radiation pattern beamwidth, while electronic beam steering.

Thus, the integrated lens antenna according to the present invention allows for electronic beam steering in a continuous angle sector while increasing radiation efficiency and reducing signal losses.