MULTIPLE INPUT MULTIPLE OUTPUT (MIMO) ANTENNA SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/726,540 filed September 4, 2018, U.S. Provisional Patent Application No. 62/730,687 filed September 13, 2018, and U.S. Provisional Patent Application No. 62/734,558 filed September 21, 2018. The entire disclosures of the above applications are incorporated herein by reference.

FIELD

[0001] The present disclosure generally relates to antenna systems/assemblies that may be low profile, wideband, multiple input multiple output (MIMO), and/or operable with low PIM (passive intermodulation).

BACKGROUND

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] With the explosive growth in wireless usage due in part to smart phones, tablet computers and a growing applications developer base, wireless operators are constantly looking for ways to increase the spectral efficiency of their networks. Distributed Antenna Systems (DAS) have been implemented across many buildings with in-building antennas to cope with the increased capacity need. In addition, more spectrum has been added in the cellular network, which requires wider bandwidth antennas. Wide bandwidth has become a great challenge along with the requirement to miniaturize CPE (customer premises equipment) device size or antenna system size to maintain a low-profile feature. Low profile omnidirectional antennas have been more popularly accepted by commercial or government buildings for the aesthetic requirement of blending well with the building ceiling architecture.

[0004] In addition, multiple input multiple output (MIMO) antenna systems are required to further increase user capacity, coverage, and cell throughput. With this requirement, it is not uncommon to use multiple antennas identical in form that are placed in very close proximity to each other due to size and space limitations. But this poses a greater challenge as where the mutual coupling has become greater and may increase the envelope cross correlation between the radiating elements.

DRAWINGS

[0005] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0006] FIG. 1 is a perspective view of an antenna system/assembly according to an exemplary embodiment in which the antenna system/assembly is low profile, wideband, MIMO, and operable with low PIM.

[0007] FIG. 2 is another perspective view of the antenna system/assembly shown in

FIG. 1.

[0008] FIG. 3 is a perspective view of the antenna system/assembly of FIG. 2 shown without the dielectric base.

[0009] FIG. 4 is a perspective view of a portion of the antenna system/assembly shown in FIG. 3, and illustrating a dielectric cable guide and a dielectric cable holder.

[0010] FIG. 5 is a perspective view of the antenna system/assembly shown in FIG. 2, and illustrating slanted upper surfaces or upper radiating patch elements of the first and second antennas of the antenna system/assembly.

[0011] FIG. 6 is a perspective view of the antenna system/assembly shown in FIG. 2, and illustrating an antenna’s capacitive loading element, suspended microstrip line, and stub for matching purposes.

[0012] FIG. 7 is an upper view the antenna shown in FIG. 6, and illustrating an extension of the upper radiating patent element.

[0013] FIG. 8 illustrates the antenna system/assembly of FIG. 2 shown positioned within an interior space cooperative defined between the dielectric base and a dielectric radome or housing.

[0014] FIG. 9 is an exploded perspective view showing the ground plane and electrically-conductive foil, tape, or film of the antenna system/assembly shown in FIG. 2.

[0015] FIG. 10 is an exploded perspective view showing the ground plane and dielectric base of the antenna system/assembly shown in FIG. 2. [0016] FIG. 11 is a perspective view of the ground plane and dielectric base shown in FIG. 10 after the ground plane has been assembled onto the dielectric base.

[0017] FIG. 12 is an exploded perspective view showing the first and second antennas positioned relative to the ground plane assembled onto the dielectric base shown in FIG. 11.

[0018] FIG. 13 is a perspective view of the first and second antennas, ground plane, and dielectric base shown in FIG. 12 after the first and second antennas have been assembled onto the ground plane.

[0019] FIG. 14 is a perspective view of the antenna system/assembly shown in FIGS. 1 through 13 after being positioned within an interior enclosure cooperatively defined by the radome and the dielectric base.

[0020] FIGS. 15 and 16 include exemplary line graphs of Voltage Standing Wave Ratio (VSWR) (Sl l) and isolation (S21 in decibels) versus frequency measured for the prototype antenna system/assembly shown in FIG 1 within a radome and with a pigtail connection as shown in FIG. 14.

[0021] FIGS. 17 and 18 include exemplary line graphs of 3D Max Gain in decibels relative to isotropic (dBi) versus frequency (MHz) measured for the prototype antenna system/assembly shown in FIG 1 within a radome and with a pigtail connection as shown in FIG. 14.

[0022] FIGS. 19, 20, 21, and 22 are exemplary line graphs of PIM (in dBc) versus frequency (in MHz) measured for port 1 (FIGS. 19 and 20) and port 2 (FIGS. 21 and 22) of the prototype antenna system/assembly shown in FIG 1 within a radome and with a pigtail connection as shown in FIG. 14.

[0023] FIG. 23 shows the pattern orientation and planes relative to the antenna system/assembly shown in FIG. 1 during radiation pattern testing.

[0024] FIGS. 24 through 45 illustrate radiation patterns (azimuth plane, Phi 0° plane, and Phi 90° plane) measured for ports 1 and 2 of the prototype antenna system/assembly shown in FIG. 1 within a radome and with a pigtail connection as shown in FIG. 14 at frequencies of about 698 MHz, 746 MHz, 824 MHz, 894 MHz, 960 MHz, 1350 MHz, 1448 MHz, 1550 MHz, 1710 MHz, 1850 MHz, 1990 MHz, 2170 MHz, 2310 MHz, 2700 MHz, 3300 MHz, 3500 MHz, 3800 MHz, 4200 MHz, 5100 MHz, 5250 MHz, 5500 MHz, and 5850 MHz, respectively. [0025] FIG. 46 is a perspective view of an antenna system/assembly according to another exemplary embodiment in which the antenna system/assembly is low profile, wideband, MIMO, and operable with low PIM.

[0026] FIG. 47 is a partially exploded perspective view of the antenna system/assembly shown in FIG. 46 without the antennas. Second and third isolators and ground plane portions are shown as separate parts that are not integrally formed with the ground plane.

[0027] FIG. 48 is a perspective view of the antenna system/assembly shown in FIG. 47 after the second isolator and ground plane portions have been positioned on the dielectric baseplate.

[0028] FIG. 49 is a perspective view of the antenna system/assembly shown in FIG. 48, and also illustrating coaxial cable feeds positioned relative to the baseplate’s dielectric cable guides and dielectric cable holders and the integrally formed tabs of the ground plane portions.

[0029] Corresponding reference numerals indicate corresponding (although not necessarily identical) parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0030] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0031] As recognized herein, there is a need for antenna systems or assemblies that are relatively low profile, wideband ( e.g ., from about 698 MHz to about 6 GHz, etc.), multiple input multiple output (MIMO), and have low or good PIM (passive intermodulation) (e.g., PIM level less than -150 dBc, etc.). Accordingly, disclosed herein are exemplary embodiments of antenna systems or assemblies (e.g., antenna system 100 shown in FIGS. 1 through 14, etc.) that may configured to be low profile, wideband, MIMO, and/or operable with low PIM. In some exemplary embodiments, the antenna systems or assemblies may be configured with a non-low PIM rated construction. Accordingly, aspects of the present disclosure and all exemplary embodiments disclosed herein are not necessarily limited to or required to have a low PIM rated construction.

[0032] In an exemplary embodiment, an antenna system may be configured to have much broader bandwidth (e.g., up to 6 GHz, etc.), relatively simpler assemblies, better radiation pattern, and/or better VSWR. In this exemplary embodiment, the antenna system may include first and second antennas having slanted upper surfaces or radiating patch elements that are non- parallel with the ground plane. The slanted antenna structures allow the antennas to have increased ( e.g ., maximized, etc.) heights, which may improve the radiation pattern such as when an additional band is included or added to the structure. This feature may be important such as when a radome having a non-flat top shape is used as a conventional flat top radiator may be unable to achieve the given required bandwidth. An additional radiating arm (broadly, radiating element) may be introduced for a frequency band from about 1350 MHz to about 1550 MHz. The additional radiating arm (e.g., 196 in FIGS. 2 and 12, etc.) may comprise two rectangular portions defining a generally L- shape, etc. A height of the of the arm may be changed with lower height of the top surface of the radiator as the arm is for higher frequencies range from about 1350 MHz to about 1550 MHz. If this arm is too high, the arm may be too inductive to match at this band. The antenna system may include a ground plane including steps with edges that may be configured accordingly to improve the VSWR and bandwidth. The antenna system may include a single shorting element, such that the antenna system has a lower number of shorting elements as compared to conventional antenna having more than one shorting element per antenna. The antenna system may include an isolator having an additional stub configured for high band (e.g., isolator 132 in FIG. 1 having a large width, etc.) and for low band. The isolation improvement by the isolator for the low band may be determined by a total length of the isolator. The location, angle of the slanting, and height of the isolator may be controlled to reduce (e.g., minimize, etc.) impact to the radiation pattern.

[0033] With reference to the figures, FIGS. 1 through 14 illustrate an exemplary embodiment of an antenna system or assembly 100 embodying one or more aspects of the present disclosure. As disclosed herein, the antenna system 100 may be configured such that the antenna system 100 is low profile, wideband, MIMO, and operable with low PIM.

[0034] As shown in FIGS. 1, 2, 3, 5, 8, 12, and 13, the antenna system 100 includes two antennas 104 (e.g., PIFAs, etc.) spaced apart from each other on a ground plane 108. In this example, the antennas 104 are identical to each other and symmetrically placed relative to a longitudinal axis along the ground plane 108. In alternative embodiments, the antennas 104 may be asymmetrically placed, may be dissimilar or non-identical, and/or configured differently than the antenna 104.

[0035] As shown in FIGS. 2, 4, 10, and 12, the antennas 104 include integrally formed tabs 112 (broadly, portions) generally parallel to the ground plane 108. The tabs 112 include openings or holes that allow the antennas 104 to be held by dielectric supports 116 (e.g., plastic spacers, plastic standoffs, plastic posts, etc.) protruding outwardly from the dielectric base 120 (e.g., plastic base plate, etc.). As shown by FIG. 10, the dielectric supports 116 protrude or extend outwardly from the dielectric base 120 for positioning through openings in the ground plane 108. The dielectric supports 116 may be integral portions (e.g., monolithically or integrally formed with, molded with, etc.) of the dielectric base 120, or the dielectric supports 116 may be discrete portions that are separately coupled to the dielectric base 120.

[0036] The dielectric supports 116 may be positioned or slotted between the dielectric base 120 and the tabs 112 that extend outwardly from the upper surfaces or radiating patch elements 180 of the antennas 104. The dielectric supports 116 may be configured to physically or mechanically support the upper radiating patch elements 180 of the antennas 104 with sufficient structural integrity. Alternative embodiments may be configured differently, such as without the dielectric spacers or standoffs or with different means for supporting the radiating patch elements and/or for coupling the antennas to the base.

[0037] The antenna system 100 includes first, second, and third isolators 128, 132, and 136. In this exemplary embodiment, the first isolator 128 may be configured to provide isolation for low band only. The second isolator 132 may be configured to provide isolation for both low band and high band. The third isolator 136 may be configured to provide isolation for high band only. The third isolator 136 may be omitted such as if the second isolator 132 is optimized, e.g., without limitation regarding mechanical concerns of fabrication. The dimensions, shapes, and locations of the first, second, and third isolators 128, 132, and 136 relative to the antennas 104 and ground plane 108 may be determined (e.g., optimized, etc.) to improve the isolation and/or to enhance bandwidth.

[0038] As shown in FIGS. 1, 5, and 9-13, the first isolator 128 is generally T-shaped and extends outwardly from the ground plane 108 to thereby increase the ground surface electrically. The first isolator 128 is generally between the antennas 104 such that isolation may be slightly improved at low band by increasing the ground surface electrically. In this example, the first isolator 128 is an integral piece or part of the ground plane 108 that has been formed (e.g., stamped, etc.) to have a T-shape that is co-planar with the ground plane 108. Alternative embodiments may include an isolator that is not T-shaped and/or that is a separate, non-integral piece electrically connected to the ground plane. [0039] As shown in FIGS. 1, 2, 3, and 10-12, the second isolator 132 comprises a multistep stub isolator including multiple surfaces or steps at different angles relative to each other. A longest step or surface of the second isolator 132 may be configured to provide isolation improvement for low band more than isolator 128. A widest step or surface of the second isolator 132 may be configured to provide isolation improvement for a high band ( e.g ., from about 1350 MHz to about 1550 MHz, etc.). If the second isolator 132 is optimized fully, the third isolator 136 may not necessarily be needed and may be omitted in exemplary embodiments.

[0040] As shown in FIGS. 10 and 11, the second isolator 132 includes integrally formed tabs 140 (broadly, portions) with openings or holes that allow the second isolator 132 to be held by dielectric supports 144 (e.g., plastic spacers, plastic standoffs, plastic posts, etc.) protruding outwardly from the dielectric base 120 (e.g., plastic base plate, etc.). As shown by FIG. 10, the dielectric supports 144 protrude or extend outwardly from the dielectric base 120 for positioning through openings in the ground plane 108. The dielectric supports 144 may be integral portions (e.g., monolithically or integrally formed with, molded with, etc.) of the dielectric base 120, or the dielectric supports 144 may be discrete portions that are separately coupled to the dielectric base 120.

[0041] With continued reference to FIG. 10, the ground plane 108 may be placed on top of the dielectric base 120 (e.g., plastic base plate, etc.), such that the dielectric supports 116, 140 pass through corresponding openings in the ground plane 108. End portions of the dielectric supports 116 may be engagingly received within openings of the tabs 112 of the antennas 104, to thereby help hold or retain the antennas 104 in place relative to the ground plane 108 and dielectric base 108. End portions of the dielectric supports 144 may be engagingly received within openings of the tabs 140 of the second isolator 132, to thereby help hold or retain the second isolator 132 in place relative to the ground plane 108 and dielectric base 108. Accordingly, the antennas 104 and second isolator 132 may thus be held together with only dielectric parts and thereby without galvanic contact.

[0042] As shown in FIGS. 1-5 and 10-12, the third isolator 136 is generally T-shaped and extends generally perpendicularly and/or vertically from the ground plane 108. The third isolator 136 is generally between the antennas 104. In this example, the third isolator 136 is an integral piece or part of the ground plane 108 that has been formed (e.g., stamped and bent, etc.) to have a T-shape generally perpendicular, vertical, and non-planar with the ground plane 108. Alternative embodiments may include a third isolator that is not T-shaped and/or that is a separate, non-integral piece electrically connected to the ground plane.

[0043] The third isolator 136 may be configured to provide isolation for high band ( e.g ., from about 1350 MHz to 1550 MHz, etc.). But in alternative embodiments with certain high band ranges, the third isolator 136 may be eliminated, which may allow for improved radiation patterns for the high band without the third isolator 136.

[0044] In exemplary embodiments, the ground plane 108 may be stamped out with integrated, integrally, or monolithically formed isolators, e.g., first, second, and/or third isolators 128, 132, 136, etc. As shown in FIGS. 1 and 9, the ground plane 108 includes integrally or monolithically formed (e.g., stamped, etc.) first and second stubs 148 along (e.g., extending outwardly from, etc.) first and second opposite sides of the ground plane 148. The stubs 148 may be configured for matching voltage standing wave ratio (VSWR) of the high frequency band.

[0045] As shown in FIG. 11, the ground plane 108 includes integrally or monolithically formed (e.g., stamped, etc.) first and second notches 152 along (e.g., extending inwardly relative to, etc.) the first and second opposite sides of the ground plane 148. The notches 152 may comprise multi-step insert or inwardly extending notches for matching both the high frequency band and the low frequency band.

[0046] As shown in FIGS. 1, 3, and 9, an electrically-conductive material 156 (e.g., aluminum foil, aluminum tape, electrically-conductive film, etc.) configured to cover an opening 160 (e.g., notch stamped, etc.) in the ground plane 108 from which ground plane material was removed (e.g., stamped, etc.) to form (e.g., integrally or monolithically form, etc.) the second isolator 132 (e.g., multistep isolator for high and low bands, etc.). In this exemplary embodiment, the electrically-conductive foil 156 comprises an aluminum foil or tape 156. The aluminum tape or foil 156 proximity couples with the ground plane 108 and covers opening(s) in the ground plane 108, e.g., created by stamped portion(s) of the ground plane 108, notched or stamped out portions of the ground plane 108, etc. The aluminum foil or tap 156 is insulated to prevent any PIM source generated due to galvanic contact. There is some amount of overlap of the aluminum foil or tape 156 and the ground plane 108, such that the overlapped aluminum foil or tape 156 and ground plane 108 electrically function as if they were built as a single part.

[0047] As shown in FIG. 10 and 14, the dielectric base 120 (e.g., plastic base plate, etc.) includes a threaded portion 162 (e.g., threaded stud, etc.) protruding outwardly from the dielectric base 120 for mounting purposes. In FIG. 14, the antenna system 100 is positioned within an interior enclosure cooperatively defined by a radome 164 and the dielectric base 120. FIG. 14 also illustrates an exemplary pigtail type connectors 166. Alternative embodiments may be configured differently, e.g., with a differently configured (e.g., shaped, sized, etc.) radome, with different connectors, etc.

[0048] FIG. 4 illustrates an exemplary dielectric guide 168 (broadly, protruding dielectric) and a dielectric holder 170 (e.g., plastic hook, etc.) protruding outwardly from the dielectric base 120. The dielectric guide 168 (e.g., plastic cable guide, etc.) is configured (e.g., protrudes outwardly relative to the ground plane 108, etc.) to guide a feed (e.g., a coaxial cable 172, etc.) for soldering. For example, the dielectric guide 168 may be used for guiding a coaxial cable 172 towards a location at which a center or inner conductor 174 of the coaxial cable 172 will be soldered to a feed point. The dielectric holder 170 is configured to maintain a height of the coaxial cable 172 (broadly, a feed) and hold the coaxial cable 172 in place. The dielectric guide 168 and dielectric holder 170 may be integral portions (e.g., monolithically or integrally formed with, molded with, etc.) of the dielectric base 120, or the dielectric guide 168 and dielectric holder 170 may be discrete portions that are separately coupled to the dielectric base 120.

[0049] As shown in FIGS. 4, 5, and 11, the ground plane 108 includes integrally formed tabs 176 (e.g., stamped and bent tabs, etc.) for soldering a coaxial cable braid 178 of the coaxial cable 172. The soldering tabs 176 provide minimum (or at least reduced) direct galvanic contact surface between the cable braid 178 and the ground plane 108 as only the cross section of the integrally formed feature contacts the ground plane 108. Advantageously, this helps to prevent (or at least reduce) any inconsistency in the contact between the cable braid 178 and the ground plane 108. In this exemplary embodiment, the ground plane 108 includes first and second pairs of stamped and bent tabs 176 that are at an acute angle (e.g., 30 degrees, etc.) relative to the ground plane 108. As shown in FIG. 5, the bottom half or portion of the cable braid 178 does not galvanically contact the ground plane 108 as the bottom portion of the cable braid 178 is within a hollow or open portion due to the stamping and repositioning of ground plane material to make the soldering tabs 176.

[0050] With reference to FIGS. 2, 3, 5, 6, and 7, the driven radiating section of each antenna 104 includes the radiating patch element 180 (or more broadly, an upper surface). The radiating patch element 180 includes an opening or slot 182 for forming multiple frequency ranges, frequency tuning, and/or matching. The slot 182 may be configured such that the antenna 104 improves the return loss level at high frequencies or high frequency bands for a higher patch. For a lower profile patch option, a slot may not be needed to improve high band in other embodiments. In this illustrated example embodiment, the slot 182 may be generally rectangular. The slot 182 may be configured for different frequency ranges and/or have any other suitable shape, for example a line, a curve, a wavy line, a meandering line, multiple intersecting lines, and/or non-linear shapes, etc., without departing from the scope of this disclosure. The slot 182 is an absence of electrically-conductive material in the radiating patch element 180. For example, the radiating patch element 180 may be initially formed with the slot 182, or the slot 182 may be formed by removing electrically-conductive material from the radiating patch element 180, such as etching, cutting, stamping, etc. In still yet other embodiments, the slot 182 may be formed by an electrically nonconductive or dielectric material, which is added to the upper radiating patch element 180 such as by printing, etc.

[0051] As shown in FIG. 5, the first and second antennas 104 are configured to have slanted upper surfaces or slanted radiating patch elements 180 that are non-parallel with the ground plane 108. In this example, the slanted upper surfaces or radiating patch elements 180 may be at an acute angle (e.g., 15 degrees, 20 degrees, 25 degrees, 30 degrees, etc.) relative to the ground plane 108. The slanted upper surfaces or radiating patch elements 180 may be configured to conform more to the top surface of the radome 164. Having the slanted upper surfaces or radiating patch elements 180 reduces or lowers the height near the feed (e.g., near the suspended microstrip line 184, etc.) and increases or heightens the height at the shorting area (e.g., at the shorting elements or legs 186, etc.). As shown in FIG. 8, the slanted upper surfaces or radiating patch elements 180 allows the antennas 104 to more fully use the internal volume defined underneath the radome 164 as compared to conventional flat radiators. This feature allows for impedance change gradually and less inductance for the high band. Consequently, bandwidth may be increased with better performance.

[0052] FIG. 5 also illustrates each antenna’s capacitive loading element 188, suspended microstrip line 184, and shorting element 186. The shorting element 186 includes a upwardly extending (e.g., upwardly bent, etc.) end portion 190 for easier soldering of the antennas 104 to the ground plane 108. The bent up end portions 190 of the shorting elements 186 and slots in the ground plane 108 as shown in FIG. 13 may allow a relatively small amount of galvanic contact for soldering and conserved heat during soldering that provides good wetting of the soldering, which, in turn, may subsequently help to reduce PIM level.

[0053] The suspended microstrip line 184 extends inwardly from a bottom portion of the feeding element 192 to define a feed for the corresponding first and second antenna 104. Each capacitive loading element 188 may be configured or formed ( e.g ., bent or folded backwardly, etc.) to provide capacitive loading to widen the bandwidth of the corresponding antenna 104 at a second, high frequency range or bandwidth. As shown in FIG. 5, the capacitive loading element 188 extends inwardly from the feeding element 192 and is disposed generally between the radiating patch element 180 and the suspended microstrip line 184 of the first or second antenna 104.

[0054] The feeding element 192 is relatively wide as the feeding element 192 may be defined or considered as being the entire illustrated side of the antenna 104 extending downwardly from the outer edge of the radiating patch element 180 towards the ground plane 108. Also shown in FIG. 6, the feeding element 192 includes upper side edge portions angled inwardly towards each other along the upper side edge portions such that an upper portion of the feeding element 192 adjacent and connected to the upper radiating patch element 108 decreases in width.

[0055] The feeding element 192 also includes a stub 194 (broadly, a portion) for matching. The stub 194 may be generally rectangular. The feeding element 192 with the tapering features and stub 194 may be configured for impedance matching purposes that broaden antenna bandwidth, such that the antenna 104 is operable across multiple frequency bands. Alternative embodiments may be configured differently, e.g., without any stub 194, with a non-rectangular stub 194, etc.

[0056] In this illustrated embodiment, the tapering features comprise side edge portions of the feeding element 192 that are slanted or angled inwardly towards the middle of feeding element 192. Stated differently, the side edge portions of the feeding element 192 are slanted or angled inwardly toward each other along these edge portions in a direction from the radiating patch element 180 downward towards the ground plane 108. Accordingly, the upper portion of the feeding element 192 adjacent and connected to the radiating patch element 180 decreases in width due to the tapering features or inwardly angled upper side edge portions. In alternative embodiments, the feeding elements 192 may include only one or no tapering features.

[0057] As shown in FIG. 7, the antenna 104 includes an extension 195 (broadly, a portion) of the upper surfaces or radiating patch element 180. The extension 195 of the radiating patch element 180 may be configured for high band ( e.g ., tuning or tweaking high band operation, etc.). In this exemplary embodiment, the extension 195 is generally triangular. Alternative embodiments may be configured differently, e.g., without any extension, with a non- triangular extension, etc.

[0058] As shown in FIGS. 2 and 12, the antenna 104 includes an addition radiating arm 196 (broadly, element). The radiating arm 196 may be configured for a frequency band from about 1350 MHz to about 1550 MHz. The radiating arm 196 may be been bent downwardly to a level suitable for the frequency band. In this example, the radiating arm 196 may comprise two rectangular portions defining a generally L-shape, etc. Alternative embodiments may be configured differently, e.g., with a differently shaped radiating arm 196, without the radiating arm, etc.

[0059] As shown in FIG. 2, the antenna 104 includes a single shorting element 186 and first and second capacitive loading elements or stubs 197 on opposite first and second sides of the shorting element 186. The single shorting element 186 may be linear or non-linear, e.g., have one or more bent portions, etc. For example, the shorting element 186 may be non-linear such that a length of the shorting element 186 between the upper radiating patch element 180 and the ground plane 108 is greater than a spaced distance separating the upper radiating patch element 108 and the ground plane 108.

[0060] The capacitive loading elements 197 are configured or formed so as to create capacitive loading for tuning the antenna 104 to one or more frequencies. For example, the capacitive loading elements 197 may be configured for tuning the antenna 104 to a first or low frequency range or bandwidth and to a second or high frequency or bandwidth.

[0061] In exemplary embodiments, the antennas 104 may be integrally or monolithically formed from a single piece of electrically-conductive non-ferromagnetic material (e.g., brass, aluminum, etc.) by stamping (e.g., via single stamping or progressive stamping technique, etc.) and then bending, folding, or otherwise forming the stamped piece of material. A wide range of materials may be used for the components of the antenna systems disclosed herein. By way of example, the antennas, isolators, and ground plane may all be made of brass or materials that are not ferromagnetic. In this example, there would preferably not be any ferromagnetic material or ferromagnetic components, which might otherwise be a source of PIM. The selection of the particular non-ferromagnetic material may depend on the suitability of the material for soldering, hardness, and costs.

[0062] FIGS. 15 through 45 provide analysis results measured for a prototype of the antenna system 100 (FIGS. 1 through 14), which was positioned within a radome and configured with a pigtail type connection as shown in FIG. 14. These analysis results are provided only for purposes of illustration and not for purposes of limitation.

[0063] More specifically, FIGS. 15 and 16 include exemplary line graphs of Voltage Standing Wave Ratio (VSWR) (Sl l) and isolation (S21 in decibels) versus frequency measured for the prototype antenna system. Generally, FIG. 15 shows that the antenna system had good VSWR ( e.g ., less than about 2, etc.) for an operating frequency from 698 megahertz (MHz) to 6 gigahertz (GHz). FIG. 16 generally shows the antenna system/assembly had good isolation ( e.g., isolation about negative 15 decibels (dB) or better, etc.) for the operating frequency from 698 MHz to 6 GHz.

[0064] FIGS. 17 and 18 include exemplary line graphs of 3D Max Gain in decibels relative to isotropic (dBi) versus frequency (MHz) measured for the prototype antenna system. Generally, FIGS. 17 and 18 show that the antenna system had good 3D Max Gain for an operating frequency from 698 MHz to 4200 MHz (FIG. 16) and for an operating frequency from 4900 MHz to 5925 MHz (FIG. 17).

[0065] FIGS. 19, 20, 21, and 22 are exemplary line graphs of PIM (in dBc) versus frequency (in MHz) measured for port 1 (FIGS. 19 and 20) and port 2 (FIGS. 21 and 22) of the prototype antenna system. Generally, FIGS. 19, 20, 21, and 22 show the low PIM performance (e.g., PIM level less than -150 dBc, etc.) at a low band (FIGS. 19 and 21) and a higher band (FIGS. 20 and 21).

[0066] FIG. 23 shows the pattern orientation and planes relative to the antenna system during radiation pattern testing. FIGS. 24 through 45 illustrate radiation patterns (azimuth plane, Phi 0° plane, and Phi 90° plane) measured for ports 1 and 2 of the prototype antenna system at frequencies of about 698 MHz, 746 MHz, 824 MHz, 894 MHz, 960 MHz, 1350 MHz, 1448 MHz, 1550 MHz, 1710 MHz, 1850 MHz, 1990 MHz, 2170 MHz, 2310 MHz, 2700 MHz, 3300 MHz, 3500 MHz, 3800 MHz, 4200 MHz, 5100 MHz, 5250 MHz, 5500 MHz, and 5850 MHz, respectively. Generally, FIGS. 24 through 45 show the quasi-omnidirectional radiation patterns (low profile antenna radiation pattern) and good efficiency of the antenna system/assembly.

[0067] FIGS. 46 through 49 illustrate an exemplary embodiment of an antenna system or assembly 200 embodying one or more aspects of the present disclosure. As disclosed herein, the antenna system 200 may be configured such that the antenna system 200 is low profile, wideband, MIMO, and operable with low PIM.

[0068] The antenna system 200 may include features or parts that correspond with and/or are similar to (although not necessarily identical) features or parts of the antenna system 100 shown in FIGS. 1 through 14. For example, the antenna system 200 may include antennas 204, a first isolator 228, and a dielectric base 220 similar to or identical to the antennas 104, first isolator 228, and dielectric base 120 of the antenna system 100.

[0069] Accordingly, the driven radiating section of each antenna 204 includes a radiating patch element 280 (or more broadly, an upper surface). The radiating patch element 280 includes an opening or slot 282 for forming multiple frequency ranges, frequency tuning, and/or matching. The antennas 204 may also include a capacitive loading element, suspended microstrip line, shorting element 286, feeding element, stub, extension 295, and additional radiating arm 296 that respectively correspond to the capacitive loading element 188, suspended microstrip line 184, shorting element 186, feeding element 192, stub 194, extension 195, and additional radiating arm 196 of the antennas 104. The antennas 204 may also include a single shorting element and first and second capacitive loading elements or stubs on opposite first and second sides of the shorting element that correspond to the single shorting element 186 and first and second capacitive loading elements or stubs 197 of the antennas 104.

[0070] The antennas 204 are configured to have slanted upper surfaces or slanted radiating patch elements 280 that are non-parallel with the ground plane 208. The slanted upper surfaces or radiating patch elements 280 may be at an acute angle ( e.g ., 15 degrees, 20 degrees, 25 degrees, 30 degrees, etc.) relative to the ground plane 208. The slanted upper surfaces or radiating patch elements 280 may be configured to conform more to the top surface of a radome. Having the slanted upper surfaces or radiating patch elements 280 reduces or lowers the height near the feed (e.g., near the suspended microstrip line, etc.) and increases or heightens the height at the shorting area ( e.g ., at the shorting elements or legs, etc.). The slanted upper surfaces or radiating patch elements 280 may allow the antennas 204 to more fully use the internal volume defined underneath a radome as compared to conventional flat radiators. This feature allows for impedance change gradually and less inductance for the high band. Consequently, bandwidth may be increased with better performance.

[0071] As shown in FIG. 47, the second and third isolators 232, 236 and ground plane portions 210 are separate parts that are not integrally formed with or integral portions of the ground plane 208. The ground plane 208 may be made of non-ferromagnetic material, such as aluminum, which may be preferable as a lower cost material that is not required to be solderable. In this example, the ground plane 208 does not necessarily have to be solderable as the antennas 204 and coaxial cables 272 may instead be soldered to the separate ground plane portions 210.

[0072] In this exemplary embodiment, the ground plane portions 210 may be brass (or other non-ferromagnetic material). The shorting legs or elements 286 of the antennas 204 and the coaxial cables 272 may soldered to the ground plane portions 210 as shown in FIGS. 46 and 49, respectively. An electrical insulator or dielectric material 211 (e.g., dielectric tape, etc.) may be disposed generally between the ground plane portions 210 and the ground plane 208 such that the ground plane portions 210 are proximity coupled to the ground plane 208 without galvanic contact.

[0073] The second isolator 232 may comprise non-ferromagnetic material, such as brass, aluminum, etc. An electrical insulator or dielectric material 233 (e.g., dielectric tape, etc.) may be disposed generally between the second isolator 232 and the ground plane 208 such that the second isolator 232 is proximity coupled to the ground plane 208 without galvanic contact. Other than being a separate part that is not integral with the ground plane 208, the second isolator 232 may otherwise include features that correspond and are similar to the features of the second isolator 132 of the antenna system 100.

[0074] The third isolator 236 may comprise non-ferromagnetic material, such as brass, aluminum, etc. An electrical insulator or dielectric material 237 (e.g., dielectric tape, etc.) may be disposed generally between the third isolator 236 and the ground plane 208 such that the third isolator 236 is proximity coupled to the ground plane 208 without galvanic contact. Other than being a separate part that is not integral with the ground plane 208, the third isolator 236 may otherwise include features that correspond and are similar to the features of the third isolator 236 of the antenna system 100.

[0075] FIG. 49 illustrates exemplary dielectric guides 268 (broadly, protruding dielectric) and dielectric holders 270 ( e.g ., plastic hook, etc.) protruding outwardly from the dielectric base 220. The dielectric guides 268 (e.g., plastic cable guide, etc.) are configured (e.g., protrudes outwardly relative to the ground plane 108, etc.) to guide feeds (e.g., coaxial cables 272, etc.) for soldering. For example, each dielectric guide 268 may be used for guiding a coaxial cable 272 towards a location at which a center or inner conductor of the coaxial cable 272 will be soldered to a feed point. The dielectric holder 270 is configured to maintain a height of the coaxial cable 272 (broadly, a feed) and hold the coaxial cable 272 in place. The dielectric guides 268 and dielectric holder 270 may be integral portions (e.g., monolithically or integrally formed with, molded with, etc.) of the dielectric base 220, or the dielectric guides 268 and dielectric holder 270 may be separate or discrete portions that are separately coupled to the dielectric base 220.

[0076] Each ground plane portion 210 includes integrally formed tabs 276 (e.g., stamped and bent tabs, etc.) for soldering a coaxial cable braid of the coaxial cable 272. The soldering tabs 276 provide minimum (or at least reduced) direct galvanic contact surface between the cable braid and the ground plane portion 210 as only the cross section of the integrally formed feature contacts the ground plane portion 210. Advantageously, this helps to prevent (or at least reduce) any inconsistency in the contact between the cable braid and the ground plane portion 210. In this exemplary embodiment, each ground plane portion 210 includes first and second pairs of stamped and bent tabs 276 that are at an acute angle (e.g., 30 degrees, etc.) relative to the ground plane portion 210.

[0077] Accordingly, exemplary embodiments are disclosed of antenna systems or assemblies. In an exemplary embodiment, the antenna system may include a ground plane, first and second antenna, and first and second isolators. Each of the first and first and second antennas may have an upper surface non-parallel with the ground plane. The first isolator may extend outwardly from the ground plane. The first isolator may be configured to provide isolation improvement for a low frequency band. The second isolator may be spaced apart from the first isolator. The second isolator may be configured to provide isolation improvement for the low frequency band and a high frequency band. [0078] The upper surface of each of the first and second antennas may be configured such that an acute angle is defined generally between the ground plane and the upper surface of each said first and second antenna.

[0079] The upper surface of each of the first and second antenna may be slanted at an acute angle relative to the ground plane.

[0080] Each of the first and second antennas may comprise a radiating patch element defining the upper surface, a feeding element extending downwardly from a first side edge of the radiating patch element, and a single shorting element extending downwardly from a second side edge of the radiating patch element that is opposite the first side edge. The single shorting element of each of the first and second antennas may include an end portion extending upwardly relative to the ground plane. The ground plane may include one or more slots adjacent the end portion of the single shorting element of each said first and second antenna.

[0081] Each of the first and second antennas may include a suspended microstrip line and a capacitive loading element. The suspended microstrip line may extend inwardly from a bottom portion of the feeding element to define a feed for the corresponding first and second antenna. The capacitive loading element may extend inwardly from a portion of the feeding element generally between the upper radiating patch element the suspended microstrip line.

[0082] The feeding element may include a stub that is configured for impedance matching and/or that comprises a generally rectangular extension of the feeding element. The feeding element may be electrically connected to the radiating patch element. The feeding element may be defined as being an entire side of the corresponding first or second antenna generally between the radiating patch element and the suspended microstrip line.

[0083] The feeding element may include upper side edge portions angled inwardly towards each other along the upper side edge portions such that an upper portion of the feeding element adjacent and connected to the radiating patch element decreases in width. The feeding element may be configured for impedance matching purposes for broadening antenna bandwidth.

[0084] Each of the first and second antennas may comprise a radiating patch element including first and second opposite side edges. The radiating patch element may define the upper surface such that the upper surface is slanted at an acute angle relative to the ground plane, thereby reducing a height of the first side edge of the radiating patch element above the ground plane and increasing a height of the second side edge of the radiating patch element above the ground plane.

[0085] The ground plane may include first and second stubs along respective first and second opposite sides of the ground plane. The first and second stubs may be configured for matching voltage standing wave ratio of the high frequency band. The ground plane may include first and second multi-step notches along the first and second opposite sides of the ground plane. The first and second multi-step notches may be configured for matching the low frequency band and the high frequency band.

[0086] Each of the first and second antennas may include a radiating arm that is configured for a frequency band from about 1350 megahertz to about 1550 megahertz and/or that includes two rectangular portions defining a generally L- shaped radiating arm. Each of the first and second antennas may include an extension that is configured for the high frequency band and/or that is generally triangular.

[0087] Each of the first and second antennas may include a single shorting element and first and second capacitive loading elements on opposite first and second sides of the single shorting element.

[0088] The first isolator may be configured to provide isolation for the low frequency band from about 698 megahertz to about 960 megahertz. The antenna system may further comprise a third isolator configured to provide isolation for the high frequency band only from about 1350 megahertz to about 1550 megahertz.

[0089] The first isolator may comprise a generally T-shaped portion that is integral with the ground plane, generally between the first and second antennas, and generally co-planar with the ground plane. The second isolator may comprise a multistep stub isolator that is integral with the ground plane. The third isolator may comprise a generally T-shaped portion that is integral with the ground plane, generally between the first and second antennas, and generally perpendicular to the ground plane.

[0090] The second isolator may comprise a multistep stub isolator having multiple steps or surfaces at different angles relative to each other. The multiple steps or surfaces may include a longest step or surface configured to provide isolation for the low frequency band, and a widest step or surface configured to provide isolation for the high frequency band including from about 1350 megahertz to about 1550 megahertz. [0091] The first isolator may comprise a generally T-shaped portion that is integral with the ground plane, generally between the first and second antennas, and generally co-planar with the ground plane. The generally T-shaped portion may increase the ground surface electrically which improves isolation at the low frequency band.

[0092] The antenna system may comprise a dielectric base including dielectric supports protruding outwardly from the dielectric base. The ground plane may include openings therethrough. The second isolator may include one or more integrally formed tabs generally parallel to the ground plane and including one or more openings. The first and second antennas may include one or more integrally formed tabs generally parallel to the ground plane and including one or more openings. The ground plane may be positioned relative to the dielectric base such that the dielectric supports extend through the corresponding openings in the ground plane and such that end portions of the dielectric supports are engagingly received within the corresponding openings of the integrally formed tabs of second isolator and the first and second antennas. The dielectric supports may help retain the second isolator and the first and second antenna in place relative to the ground plane without galvanic contact.

[0093] The antenna system may comprise a dielectric base including at least one dielectric guide protruding outwardly from the dielectric base, and at least one dielectric holder protruding outwardly from the dielectric base. The dielectric guide may be configured to guide a coaxial cable to a location for soldering an inner conductor of the coaxial cable to a feed point of the antenna system. The dielectric holder may be configured to help maintain a height of the coaxial cable and hold the coaxial cable in place.

[0094] The antenna system may include an electrically-conductive tape or foil coupled to the ground plane via proximity coupling. The electrically-conductive tape or foil may be positioned relative to the ground plane to cover one or more openings stamped into the ground plane. The electrically-conductive tape or foil may be electrically insulated to avoid galvanic contact with the ground plane and avoid PIM source generated thereby. At least a portion of the electrically-conductive tape or foil may overlap at least a portion of the ground plane, whereby the overlapped the electrically-conductive tape or foil and the ground plane may be electrically operable collectively as a single part.

[0095] The ground plane, the first and second isolators, and the first and second antennas may be made of non-ferromagnetic material. The ground plane may include integrally formed tabs to which are solderable cable braids. The antenna system may be operable with passive intermodulation level less than -150 decibels relative to carrier for frequencies from about 698 megahertz to about 4200 megahertz.

[0096] The antenna system may be configured such that the antenna system is low profile, wideband, multiple input multiple output (MIMO), and/or operable with low passive intermodulation.

[0097] Exemplary embodiments of the antenna systems ( e.g ., antenna system 100 shown in FIGS. 1 through 14, etc.) disclosed herein are suitable for a wide range of applications, e.g., that use more than one antenna, such as LTE/4G applications and/or infrastructure antenna systems (e.g., customer premises equipment (CPE), satellite navigation systems, alarm systems, terminal stations, central stations, in-building antenna systems, etc.). An antenna system disclosed herein may be configured for use as a low profile, low PIM, wideband, and MIMO antenna system, although aspects of the present disclosure are not limited solely to low profile, low PIM, wideband, and MIMO antenna systems. An antenna system (e.g., antenna system 100 shown in FIGS. 1 through 14, etc.) disclosed herein may be implemented and incorporated inside an electronic device, such as machine to machine, vehicular, in-building unit, etc. In which case, the internal antenna components would typically be internal to and covered by the electronic device housing. As another example, the antenna system may instead be housed within a radome, which may have a low profile. In this latter case, the internal antenna components would be housed within and covered by the radome. Accordingly, the antenna systems disclosed herein should not be limited to any one particular end use.

[0098] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well- known technologies are not described in detail. In addition, advantages and improvements that may be achieved with one or more exemplary embodiments of the present disclosure are provided for purpose of illustration only and do not limit the scope of the present disclosure, as exemplary embodiments disclosed herein may provide all or none of the above mentioned advantages and improvements and still fall within the scope of the present disclosure.

[0099] Specific dimensions, specific materials, specific shapes, and/or specific antenna operational performance data disclosed herein are example in nature and do not limit the scope of the present disclosure. The disclosure herein of particular values and particular ranges of values for given parameters are not exclusive of other values and ranges of values that may be useful in one or more of the examples disclosed herein. Moreover, it is envisioned that any two particular values for a specific parameter stated herein may define the endpoints of a range of values that may be suitable for the given parameter (i.e., the disclosure of a first value and a second value for a given parameter can be interpreted as disclosing that any value between the first and second values could also be employed for the given parameter). For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if parameter X is exemplified herein to have values in the range of 1 - 10, or 2 - 9, or 3 - 8, it is also envisioned that Parameter X may have other ranges of values including 1 - 9, 1 - 8, 1 - 3, 1 - 2, 2 - 10, 2 - 8, 2 - 3, 3 - 10, and 3 - 9.

[0100] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. For example, when permissive phrases, such as“may comprise”,“may include”, and the like, are used herein, at least one embodiment comprises or includes the feature(s). As used herein, the singular forms“a,”“an,” and“the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0101] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or“coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being“directly on,”“directly engaged to,” “directly connected to,” or“directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion ( e.g .,“between” versus“directly between,” “adjacent” versus“directly adjacent,” etc.). As used herein, the term“and/or” includes any and all combinations of one or more of the associated listed items.

[0102] The term“about” when applied to values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by“about” is not otherwise understood in the art with this ordinary meaning, then“about” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters. For example, the terms“generally,”“about,” and“substantially,” may be used herein to mean within manufacturing tolerances (e.g., angle +/- 30’, 0-place decimal +/- .5, l-place decimal +/- .25, 2-place decimal +/-.13, etc.). Whether or not modified by the term“about,” the claims include equivalents to the quantities.

[0103] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as“first,”“second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0104] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,”“above,”“upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as“below” or“beneath” other elements or features would then be oriented“above” the other elements or features. Thus, the example term“below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0105] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements, intended or stated uses, or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.