Angle of arrival antenna system

Abstract

An angle of arrival antenna system uses two orthogonal arrays of patch antenna elements to measure the angle of arrival of a wireless signal without regard to its polarization. Each antenna element has an antenna patch located above a corresponding ground patch. A shorting wall directly electrically connects one edge of the antenna patch to a corresponding edge of the underlying ground patch. The edge of the ground patch is also directly connected to a system ground plane. The other edges of the ground patch are not connected to the system ground plane. The shorting wall acts as an impedance that isolates the ground patch from the system ground plane and thus improves isolation between the antenna elements. By implementing each shorting wall as an array of plated vias or slots, the antenna system can be constructed using conventional circuit board manufacturing techniques.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 118,348, filed November 25, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0003] The angle of arrival (AOA) of a signal is the direction in which a signal is received. The signal can be an electromagnetic signal (e.g., radio frequency or microwave) propagating through air or space. In this case, an antenna array receives the electromagnetic signal and calculates the AOA based on the time difference of arrival between array elements (i.e., the measured phase difference). AOA measurements are used for radio positioning and radio direction finding. Applications include multi-angle measurements and multi-point positioning, mobile phone tracking, radar, location-based services, and real-time tracking systems. Summary of the Invention

[0004] This embodiment is characterized by an angle-of-arrival (AOA) antenna system that uses two orthogonal arrays of patch antenna elements to measure the AOA of a wireless signal. Each antenna element has an antenna patch located above a corresponding ground patch. A short-circuit wall electrically connects one edge of the antenna patch to the corresponding edge of the ground patch below. The edge of the ground patch is also directly connected to the system ground plane. The other edges of the ground patch are not connected to the system ground plane.

[0005] Advantageously, the short-circuit wall acts as an impedance that isolates the ground patch from the system ground plane across the antenna bandwidth. In contrast, prior art AOA systems and antenna arrays typically use single-ended antenna elements sharing a single ground. The short-circuit wall improves isolation between antenna elements by preventing radio frequency (RF) currents received at one antenna element from coupling to the outputs of other antenna elements. These cross-coupled currents can erroneously cause phase shifts in the outputs of antenna elements, thus acting as a source of system error. By improving isolation between antenna elements, this source of system error is reduced, and this embodiment can produce AOA measurement results with higher accuracy compared to prior art AOA systems and antenna arrays using single-ended antennas.

[0006] The patch antenna elements of this embodiment are described herein as "quasi-balanced," meaning that each patch antenna element has characteristics similar to a fully balanced antenna, but can be driven like a single-ended antenna. For clarity, consider each patch antenna element without a short-circuit wall. Further assume that the antenna and ground patch have the same geometry. In this case, the antenna and ground patch have the same impedance, just like a fully balanced antenna. With the ground patch connected to the system ground plane, the symmetry of the structure is broken, and the ground patch acts more like a single-ended antenna. When a short-circuit wall is included, it modifies the electric field boundary conditions, thereby isolating the ground patch from the system ground plane. In fact, the short-circuit wall can be considered as a balun (balanced-to-unbalanced converter), which converts the mismatched impedance between the system ground plane and the single-ended antenna feed to a balanced impedance between the antenna and the ground patch. Because this "balun effect" is integral to the physical structure of the antenna element, it can be driven in a single-ended manner (i.e., using a single-ended antenna feed and the system ground plane). No external balun or other type of impedance converter is required. Advantageously, compared to existing AOA systems that require baluns, the elimination of baluns reduces losses, number of parts, and size.

[0007] This embodiment includes an AOA antenna system that uses quasi-balanced patch antenna elements instead of single-ended patch antenna elements. Due to the structure of the quasi-balanced patch antenna, this embodiment is unaffected by noise picked up by the system ground plane or other antenna elements. The determined AOA is also less sensitive to the polarization of the input wireless signal. The quasi-balanced patch antenna forces noise current to flow uniformly across the antenna and ground patch. This noise current is common-mode with the antenna elements and is suppressed by the output transmission lines differentially connected to the antenna elements.

[0008] Another advantage of this embodiment is that it can receive wireless signals from either a direction perpendicular to the array plane (i.e., the wide side) or a direction parallel to the array plane (i.e., end-fire). In contrast, single-ended patch antenna arrays can only operate in a wide-side configuration. Both of these advantages simplify how this embodiment can be oriented.

[0009] In an embodiment, the AOA antenna system includes an array of first antenna elements along a first direction. Each first antenna element has a first antenna patch positioned above a corresponding first ground patch. A first edge of the first antenna patch is parallel to the first direction, and a second edge of the first ground patch is parallel to the first direction and electrically connected to the first edge. The AOA antenna system also includes an array of second antenna elements along a second direction orthogonal to the first direction. Each second antenna element has a second antenna patch positioned above a corresponding second ground patch. A third edge of the second antenna patch is parallel to the second direction, and a fourth edge of the second ground patch is parallel to the second direction and electrically connected to the third edge. The AOA antenna system also includes a system ground plane having (i) a first ground plane edge parallel to the first direction and directly electrically connected to each second edge, and (ii) a second ground plane edge parallel to the second direction and directly electrically connected to each fourth edge. Attached Figure Description

[0010] Figure 1 and Figure 2 This is a perspective view of the patch antenna element in the embodiment. Figure 1 The image shows an antenna element without an antenna patch, while... Figure 2 An antenna element with an antenna patch is shown.

[0011] Figure 3 Four are shown in the embodiment. Figure 1 and Figure 2 Antenna arrays are used to measure the angle of arrival (AOA) of wireless signals using antenna elements.

[0012] Figure 4 yes Figure 3 The graphs showing the reflection versus frequency for all four antenna elements are shown.

[0013] Figure 5 yes Figure 3 The graph shows the cross-coupling frequency of all paired antenna elements.

[0014] Figure 6 Show Figure 4 The graph is a curve, but magnified.

[0015] Figure 7 yes Figure 3 The graph shows the simulated transfer function of the AOA antenna array.

[0016] Figure 8 Implementation shown in the embodiments Figure 3 The middle layer of the printed circuit board (PCB) of the AOA antenna array.

[0017] Figure 9 Examples shown Figure 8 The top layer of the PCB.

[0018] Figure 10 Examples shown Figure 8 The bottom layer of the PCB.

[0019] Figure 11 The first via array and the second via array are shown in the embodiment.

[0020] Figure 12 The embodiments illustrate how each antenna element can be used as a short-circuit wall using a slot via.

[0021] Figure 13 As shown in the embodiments, it is possible to Figure 12 How to translate the slot vias so that the first longitudinal edge of each slot via coincides with the second edge of each antenna element.

[0022] Figure 14 As shown in the embodiments, it is possible to Figure 12 How to translate the slot vias so that the second longitudinal edge of each slot via coincides with the second edge of each antenna element.

[0023] Figure 15 The example shown includes only one short-circuit wall without gaps.

[0024] Figure 16 As shown in the embodiments Figure 15 The antenna components can be soldered onto the PCB.

[0025] Figure 17 The use shown in the embodiments Figure 15 The four antenna elements and Figure 16 AOA antenna array on PCB.

[0026] Figure 18 As shown in the embodiments Figure 15 How can the antenna element be formed at a right angle relative to the ground patch?

[0027] Figure 19 As shown in the embodiments Figure 15 How can the antenna element form an acute angle relative to the ground patch?

[0028] Figure 20 As shown in the embodiments Figure 15 How the antenna element forms an obtuse angle relative to the ground patch. Detailed Implementation

[0029] Figure 1 and Figure 2This is a perspective view of a quasi-balanced patch antenna element 100, which includes an antenna patch 104 located above a ground patch 102. Figure 1 The antenna element 100 without the antenna patch 104 is shown, while Figure 2 An antenna element 100 with an antenna patch 104 is shown. Figure 1 and Figure 2 In the diagram, antenna patch 104 and ground patch 102 are shown as planar conductive elements, which are placed flat in the xy plane (see right-hand coordinate system 120) and therefore parallel to each other. Antenna patch 104 and ground patch 102 are also shown to have the same length 116 in the x-direction and the same width 118 in the y-direction. Antenna patch 104 is positioned directly above ground patch 102 in the z-direction, that is, each edge of antenna patch 104 is directly above and parallel to the corresponding edge orientation of ground patch 102. Antenna patch 104 and ground patch 102 are separated by patch offset 122 in the z-direction.

[0030] like Figure 2 As shown, the antenna patch 104 has a first edge 124 parallel to the x-direction. The ground patch 102 has a corresponding second edge 126, which is parallel to the first edge 124 and therefore also parallel to the x-direction. The second edge 126 is directly electrically connected to the system ground plane 108, which is coplanar with the ground patch 102.

[0031] The first edge 124 and the second edge 126 are electrically connected to each other to change the transmission / reception characteristics of the antenna element 100. Figure 1 and Figure 2 In the example, the first edge 124 and the second edge 126 are electrically connected via a first short-circuit wall 106(1) and a second short-circuit wall 106(2) formed of a conductive material (e.g., copper). Each of the short-circuit walls 106(1) and 106(2) has opposing fifth edges 130 and sixth edges 132 parallel to the x-direction. The fifth edge 130 is directly electrically connected to the first edge 124, and the sixth edge 132 is directly electrically connected to the second edge 126. Here, "directly" means without any intermediate components or conductors (except for solder, conductive epoxy, or similar materials used to ensure electrical contact between the first edge 124 and the fifth edge 130, and between the second edge 126 and the sixth edge 132).

[0032] Antenna patch 104 is electrically connected to antenna feed 110, which includes a via surrounded by a non-conductive ring 112. Antenna feed 110 may include transmission lines continuing beneath ground patch 102 and system ground plane 108 (see...). Figure 10Transmission line 1010 in the diagram). The transmission line may continue below the gap 114 formed between short-circuit walls 106(1) and 106(2). As described in more detail below, the gap 114 provides space for the transmission line to pass along the conductive layers of the circuit board below the ground patch 102 and the system ground plane 108 as the short-circuit walls 106(1) and 106(2) traverse all layers of the circuit board. When the gap 114 is included, its width in the x-direction can be very small compared to the design wavelength of the antenna element 100, thereby ensuring that the effect of the gap on the performance of the antenna element 100 is negligible (compared to the case where only one short-circuit wall 106 extends along the entire length of edges 124 and 126, as shown below). Figure 15 (As shown).

[0033] Figure 3 Angle of Arrival (AOA) antenna array 300 is shown, which uses four Figure 1 and Figure 2 A quasi-balanced patch antenna element 100 is used to measure the AOA of the wireless signal 320. The AOA antenna array 300 includes: a first linear array of antenna elements 100 spaced apart along a first direction; and a second linear array of antenna elements 100 spaced apart along a second direction perpendicular to the first direction. Figure 3 In the example, the first direction is the y-direction, and the second direction is the x-direction. The first linear array includes a first antenna element 100(1) and a second antenna element 100(2) spaced apart by a first spacing 312, and the second linear array includes a third antenna element 100(3) and a fourth antenna element 100(4) spaced apart by a second spacing 314. Although Figure 3 The diagram shows each of the first and second linear arrays having two antenna elements 100; however, without departing from the scope of this document, one or both of the first and second linear arrays may include more than two antenna elements 100. For example, the first and second linear arrays may each have three antenna elements 100.

[0034] exist Figure 3In this embodiment, a first spacing 312 and a second spacing 314 are measured between the phase centers of adjacent antenna elements 100. To avoid π-ambiguity, each of the first spacing 312 and the second spacing 314 should be less than half the free-space wavelength λ of the wireless signal 320 (i.e., λ / 2). For example, if the wireless signal 320 has a frequency of 2.45 GHz, then each of the first spacing 312 and the second spacing 314 should be less than approximately 61.2 mm. In one embodiment, the first spacing 312 and the second spacing 314 are equal. In embodiments where the first linear array contains more than two antenna elements 100, the first spacing 312 may be uniform, i.e., the same for each pair of adjacent antenna elements 100. Alternatively, the first spacing 312 may be non-uniform. Similarly, when the second linear array contains more than two antenna elements 100, the second spacing 314 may be uniform or non-uniform.

[0035] The system ground plane 108 has a first ground plane edge 304 parallel to a first direction and a second ground plane edge 306 parallel to a second direction. Ground plane edges 304 and 306 converge at a corner 322. For each antenna element 100 of the first linear array, the second edge 126 is directly electrically connected to the first ground plane edge 304. Similarly, for each antenna element 100 of the second linear array, the second edge 126 is directly electrically connected to the second ground plane edge 306. Therefore, in Figure 3 In the first antenna element 100 (1) and the second antenna element 100 (2), the second edges 126 are directly electrically connected to the first ground plane edge 304, and the second edges 126 of the third antenna element 100 (3) and the fourth antenna element 100 (4) are directly electrically connected to the second ground plane edge 306. However, when one or both of the first linear array and the second linear array include more than two antenna elements 100, the first ground plane edge 304 and the second ground plane edge 306 may be extended accordingly, such that all antenna elements 100 are similarly connected to the system ground plane 108.

[0036] Since the ground plane edges 304 and 306 serve as the boundaries of the system ground plane 108 in the xy plane, the system ground plane 108 does not extend into the region directly between the first antenna element 100(1) and the second antenna element 100(2), or into the region directly between the third antenna element 100(3) and the fourth antenna element 100(4). Equivalently, each ground patch 102 is directly electrically connected to the system ground plane 108 only along the second edge 126; that is, all other edges of the ground patch 102 are not directly electrically connected to the system ground plane 108. This geometry increases the isolation between the first antenna element 100(1) and the second antenna element 100(2), and between the third antenna element 100(3) and the fourth antenna element 100(4).

[0037] The phase center of the second antenna element 100(2) is offset by a first offset 316 from the corner 322 along a first direction, and the phase center of the third antenna element 100(3) is offset by a second offset 318 from the corner 322 along a second direction. The offsets 316 and 318 can be selected to increase the isolation between the second antenna element 100(2) and the third antenna element 100(3). For example, the offsets 316 and 318 can be selected such that the two-dimensional distance between the phase centers of the antenna elements 100(2) and 100(3) in the xy plane is approximately λ / 2. Figure 3 In the example, the first offset 316 is a portion of the first spacing 312, and the second offset 318 is a portion of the second spacing 314. In some embodiments, the first offset 316 is half of the first spacing 312, and the second offset 318 is half of the second spacing 314. In some embodiments, the first offset 316 and the second offset 318 are equal.

[0038] Figure 3The diagram also illustrates how antenna elements 100(1), 100(2) of a first linear array can be fabricated on a printed circuit board (PCB) up to a first board edge 308, and how antenna elements 100(3), 100(4) of a second linear array can be fabricated on a PCB up to a second board edge 310. Specifically, each antenna patch 104 has an edge 131 opposite to a first edge 124, and each ground patch 102 has an edge 128 opposite to a second edge 126. The edges 128, 131 of the first antenna element 100(1) and the second antenna element 100(2) can be aligned with the first board edge 308, while the edges 128, 131 of the third antenna element 100(3) and the fourth antenna element 100(4) can be aligned with the second board edge 310. In some embodiments, the edges 128, 131 are not aligned with the board edges 308, 310. For example, the edges 128, 131 can be offset from the board edges 308, 310 by a dielectric material.

[0039] Figures 4 to 6 Show Figure 3 The simulated behavior of the AOA antenna array 300. Specifically, Figure 4 It is a graph of the reflection coefficient versus frequency for all four quasi-balanced patch antenna elements 100(1), 100(2), 100(3), and 100(4). Figure 5 It is a graph of the cross-coupling coefficients versus frequency for all pairs of quasi-balanced patch antenna elements 100(1), 100(2), 100(3), and 100(4). Figure 6 Show Figure 4 The curves are shown, but magnified near the resonant frequency to distinguish the curves of the four quasi-balanced patch antenna elements 100(1), 100(2), 100(3), and 100(4). Figures 4 to 6 Best viewed in conjunction with the description below.

[0040] Assuming all four antenna elements 100(1), 100(2), 100(3), and 100(4) have the same geometry, the AOA antenna array 300 is obtained through numerical simulation. Figures 4 to 6The data is as follows. Specifically, the length 116 of each antenna element 100 is set to 20.00 mm, and the width 118 of each antenna element 100 is set to 14.91 mm. The distance in the xy plane between each antenna feed 110 and its corresponding second edge 126 is set to approximately 3.37 mm. It is assumed that the antenna patch 104, ground patch 102, and system ground plane 108 are formed of one ounce of copper on a PCB with FR-4 as the dielectric material. It is also assumed that FR-4 is located between each antenna patch 104 and its corresponding ground patch 102. Spacings 312 and 314 are each set to 49.5 mm, and offsets 316 and 318 are each set to 25 mm.

[0041] The AOA antenna array 300 is based on complex frequency-related S-parameters. ij Numerical modeling is performed using a 4×4 scattering matrix, where i and j are the indices of the four antenna elements 100(1), 100(2), 100(3), and 100(4). For each antenna element 100(i), the diagonal element S is used at several frequencies. ii The reflection coefficient is calculated from the amplitude. For each pair of antenna elements 100(i) and 100(j), where i≠j, the reflection coefficient is also calculated from the off-diagonal element S at several frequencies. ij The cross-coupling coefficient is calculated based on the magnitude of the cross-coupling coefficient.

[0042] Figure 4 The reflection coefficients of four antenna elements 100(i) are shown at a span of 1 GHz and a frequency spacing of 1 MHz. The reflection coefficients are represented by four corresponding curves that are too similar to be distinguishable at these scales. Each antenna element 100(i) resonates near 2.45 GHz (i.e., the center of the ISM band spanning 2.4 GHz to 2.5 GHz). At resonance, each antenna element 100(i) has a reflection coefficient of approximately -16.5 dB. When measured at the -10 dB point, the full width at each resonance is approximately 40 MHz.

[0043] Figure 5 Showing for with Figure 4 The cross-coupling coefficients of four antenna elements 100(i) within the same frequency range. Solid curve 502 indicates the cross-coupling coefficients (i.e., S-parameters S) of the second antenna element 100(2) and the third antenna element 100(3). 23The short dashed curve 504 indicates the cross-coupling coefficient of the first antenna element 100(1) and the second antenna element 100(2). Due to symmetry, curve 504 also indicates the cross-coupling coefficient of the third antenna element 100(3) and the fourth antenna element 100(4). The long dashed curve 506 indicates the cross-coupling coefficient of the first antenna element 100(1) and the third antenna element 100(3). Due to symmetry, curve 506 also indicates the cross-coupling coefficient of the second antenna element 100(2) and the fourth antenna element 100(4). The dashed curve 508 indicates the cross-coupling coefficient of the first antenna element 100(1) and the fourth antenna element 100(4).

[0044] from Figure 5 The two antenna elements 100 closest to corner 322 (i.e., second antenna element 100(2) and third antenna element 100(3)) exhibit the largest cross-coupling. Advantageously, the cross-coupling coefficient is no greater than approximately -25 dB. Cross-coupling between pairs of antenna elements 100 (e.g., antenna elements 100(1) and 100(2)) within each linear array is suppressed when the phase centers are spaced apart by λ / 2. With this spacing, each antenna element 100 of the linear array is located at the null of the radiation pattern of its immediate neighbor, which advantageously reduces cross-coupling. However, as mentioned above, the spacing between phase centers should be less than λ / 2 to avoid π ambiguity. Therefore, in the numerical simulation, the value of 49.5 mm chosen for the first spacing 312 and the second spacing 314 results in λ / 2 = 61.2 mm at less than 2.45 GHz. Due to this value of the first spacing 312 and the second spacing 314, some cross-coupling exists between adjacent antenna elements 100. For curves 506 and 508, the increased distance between a pair of antenna elements 100 (one antenna element is located in the first linear array and the other antenna element is located in the second linear array) further reduces cross-coupling.

[0045] Figure 6 The figure illustrates an alternative way to quantize the impact of cross-coupling on the performance of antenna element 100. If there is no cross-coupling between any pair of antenna elements 100 (i.e., for all off-diagonal elements, S...), ij =0), then Figure 4 The four curves in the diagram will be identical. However, cross-coupling affects antenna element 100 by distorting and shifting the resonance. Figure 6This effect can be seen in the curves 602, 604, 606, and 608, which represent the reflection coefficients of antenna elements 100(1), 100(2), 100(3), and 100(4), respectively. The minimum values ​​of curves 602, 604, 606, and 608 differ by up to 2 MHz in frequency and by up to 0.1 dB in reflection coefficient. This small shift is a direct result of the improved isolation between antenna elements 100 obtained by the short-circuit wall 106.

[0046] Figure 7 This is a graph of the simulated transfer function of the AOA antenna array 300. For the AOA between -90° and +90°, simulated data points 706 are calculated in steps of 10°. These simulated data points are... Figure 7 The diagram shows the connection made up of dashed lines. (Using...) Figures 4 to 6 The same geometry and assumptions are used to calculate data point 706. Furthermore, the antenna array 300 has… Figure 3 The orientation is shown. The frequency of the wireless signal 320 is set to 2.45 GHz. Furthermore, it is assumed that the wireless signal 320 propagates in the -y direction, such that the wireless signal is received by the side of antenna elements 100(3), 100(4) opposite to the short-circuit wall 106. It is further assumed that the wireless signal 320 is linearly polarized along the z direction. AOA is the angle between the first direction of the AOA antenna array 300 and the y direction in the xy plane (i.e., the propagation direction of the wireless signal 320 is fixed when the AOA antenna array 303 rotates). Therefore, in Figure 3 In the middle, the first direction is the y direction, and the antenna array 300 is oriented at 0° AOA.

[0047] exist Figure 7 In the diagram, line 704 represents the ideal linear response, while residual 702 is equal to the difference between the simulated data point 706 and line 704. Marker 710 at -70° indicates an error of -2.033°, and marker 712 at +70° indicates an error of -3.77°. Simulations at other frequencies (e.g., 2.4 GHz and 2.5 GHz) and polarizations (e.g., 45° and 70° relative to the z-axis) show similar results.

[0048] Figures 8 to 10 Implementations are shown separately. Figure 3 The AOA antenna array 300's PCB 840 comprises a middle layer 850, a top layer 950, and a bottom layer 1050. PCB 840 includes... Figures 1 to 3The four quasi-balanced patch antenna elements 100(1), 100(2), 100(3), 100(4) are similar to the four quasi-balanced patch antenna elements 800(1), 800(2), 800(3), 800(4), except that each quasi-balanced patch antenna element 800 uses a first via array 1002(1) and a second via array 1002(2) as a first short-circuit wall 106(1) and a second short-circuit wall 106(2). Figure 11 The first via array 1002(1) and the second via array 1002(2) are shown in more detail. Figures 8 to 10 The image shows PCB 840, whose geometry is similar to that used to generate Figures 4 to 7 The geometry of the PCB is shown in the curve diagram. Figures 8 to 11 Best viewed in conjunction with the description below.

[0049] In the intermediate layer 850, the system ground plane 108 and four grounding patches 102(1), 102(2), 102(3), and 102(4) form a continuous planar metal sheet. (As in...) Figure 8 The continuous planar metal sheet shown in black can be one ounce of copper, two ounces of copper, nickel-plated copper, gold-plated copper, or another type of metal commonly used in PCB manufacturing. Figure 8 In the middle, the system grounding plane 108 is shaped into a right-angled triangle, which is different from... Figure 3 The rectangular shape shown is an example geometry. The system ground plane 108 may alternatively be shaped without departing from the scope of this document.

[0050] In the top layer 950, each antenna patch 104 is located directly above its corresponding ground patch 102. In the bottom layer 1050, switch 1020 has four inputs, each connected to a corresponding transmission line 1010. The output 1022 of switch 1020 transmits the electrical signal received from one of the four antenna elements 800 to additional circuitry (not shown) for signal processing. Each transmission line 1010 is also connected to the antenna feed 110 of its corresponding antenna element 800.

[0051] Each via array 1002(1), 1002(2) has two rows of plated through-holes that penetrate all layers of the PCB 840. Therefore, it should be understood that via arrays 1002(1), 1002(2) also penetrate the intermediate layer 850 and the top layer 950, even though these via arrays are... Figure 8 and Figure 9 The vias are not visible. They may be filled with solder or another conductive material to enhance the electrical contact between each antenna patch 104 and its corresponding ground patch 102.

[0052] Figure 11The via arrays 1002(1), 1002(2) are shown to form a gap 114 through which the transmission line 1010 passes to reach the antenna feed 110. Each via array 1002(1), 1002(2) is shown as two parallel rows of 19 vias each. However, without departing from the scope of this document, each via array 1002(1), 1002(2) may have only one row or more than two rows. Similarly, without departing from the scope of this document, each row may have more than 19 vias or fewer than 19 vias. Without departing from the scope of this document, the diameter of each via may be greater than or less than [the specified value]. Figure 11 As shown. Vias can be plated so that these vias are electrically connected to their neighbors on the top and / or bottom layers of the PCB 840.

[0053] Advantageously, the via arrays 1002(1), 1002(2) implement the first short-circuit wall 106(1) and the second short-circuit wall 106(2) using circuit board manufacturing techniques known in the art. For example, each transmission line 1010 can be implemented as a microstrip, wherein the width of the transmission line 1010 is selected such that the characteristic impedance of the transmission line matches the characteristic impedance of the antenna element 800 to which the transmission line is connected. Alternatively, each transmission line 1010 can be implemented using another type of planar microwave transmission line (e.g., coplanar waveguide, stripline, slot line, etc.). The metal traces (including the transmission lines 1010) and the metal used to plate the vias of the via arrays 1002(1) and 1002(2) are typically copper. However, other metals (e.g., nickel, silver, tin) or combinations thereof can be used.

[0054] Figure 12 This illustrates how each quasi-balanced patch antenna element 800 uses a first slot via 1202(1) and a second slot via 1202(2) as a first short-circuit wall 106(1) and a second short-circuit wall 106(2). The slot vias 1202(1), 1202(2) can also be manufactured using circuit board manufacturing techniques known in the art. For example, each slot via 1202 can be manufactured by milling a linear through-hole or slot along the x-direction and through all layers of the circuit board. Each machined slot can then be metal-plated to electrically short the antenna patch 104 to its corresponding ground patch 102. Similar to... Figure 10 The plated vias, slot vias 1202(1) and 1202(2) can be filled with solder or another conductive material to enhance electrical contact.

[0055] Figures 12 to 14 This illustrates how slot vias 1202(1), 1202(2) can be positioned relative to a second edge 126 that defines the boundary between the system ground plane 108 and the ground patch 102. Figure 12In this configuration, the second edge 126 passes along the centerline of each slot via 1202, such that the first half of each slot via 1202 overlaps with the system ground plane 108, and the second half overlaps with the ground patch 102. However, the slot vias 1202(1), 1202(2) can be translated so that the centerlines of these slot vias do not coincide with the second edge 126. For example, in Figure 13 In this process, the slot vias 1202(1) and 1202(2) have been translated along the -y direction, such that the first longitudinal edge 1306 of each slot via 1202 coincides with the second edge 126. In this case, each slot via 1202 completely overlaps with the system ground plane 108. Figure 14 In this process, the slot vias 1202(1) and 1202(2) have been translated in the +y direction, such that the second longitudinal edge 1408 of each slot via 1202 coincides with the second edge 126. In this case, each slot via 1202 completely overlaps with the ground patch 102. Without departing from the scope of this document, the slot vias 1202(1) and 1202(2) can be translated in the +y direction and... Figures 12 to 14 The different quantities shown. Furthermore, Figures 12 to 14 The translations depicted in the text are applicable to Figure 10 and Figure 11 Via arrays 1002(1) and 1002(2). Therefore, it is not necessary to position each via array 1002 such that the second edge 126 continues between the two rows of vias.

[0056] exist Figures 8 to 14 In this embodiment, one or more non-conductive layers of the PCB 840 are partially located between each antenna patch 104 and its ground patch 102. These layers are formed of a dielectric material that affects the characteristics of each antenna element 800. Therefore, the PCB 840 can be constructed using a dielectric material that has low loss (e.g., loss tangent) over the bandwidth of the antenna element 800. Examples of such dielectric materials include PTFE, ceramics, polyimide, Rogers RO4000 series laminates, AGC-Nelco Meteorwave 8000 series laminates, G10, etc. FR-4 can also be used.

[0057] Figures 15 to 17 This shows that, apart from using four gapless quasi-balanced patch antenna elements 1500, it is similar to... Figure 3The AOA antenna array 300 is similar to the AOA antenna array 1700. Here, "gapless" means that each antenna element 1500 includes only one short-circuit wall 1506 and no gap 114. Each antenna element 1500 can be formed, for example, by bending a metal plate to form the antenna patch 104 and the short-circuit wall 1506. The first edge 124 and the fifth edge 130 appear where the metal plate is bent. The sixth edge 132 can then be directly soldered to or epoxy-bonded to the top metal layer of the PCB 1600 at the corresponding second edge 126. Figure 16 The metal top layer of PCB 1600 forming ground patch 102 and system ground plane 108 is shown. Antenna feed 110 can pass through ring 112 to be soldered to antenna patch 104.

[0058] Compared to the AOA antenna array 300, the AOA antenna array 1700 does not require vias that pass through all layers of the PCB 1600. Therefore, the AOA antenna array 1700 does not use via array 1002 or slot vias 1202 to electrically connect each antenna patch 104 to its ground patch 102. Without via array 1002 and slot vias 1202, the transmission line 1010 is no longer restricted to passing directly below the gap 114, providing greater freedom in designing and routing the transmission line 1010 on the PCB 1600.

[0059] Another advantage of the AOA antenna array 1700 is that if all transmission lines 1010 are laid on the bottom layer of PCB 1600, then PCB 1600 can be a double-layer board (i.e., without an inner layer). This contrasts with boards having more than two layers (e.g., ...). Figures 7 to 9 Compared to the PCB840 (which requires at least three layers), double-layer boards are cheaper and easier to manufacture.

[0060] Another advantage of the AOA antenna array 1700 is that it can be used to manufacture antenna element 1500, whose patch offset 122 cannot be achieved using multilayer circuit boards. Most two-layer circuit boards are 1.57 mm (0.063”) thick, while most four-layer circuit boards are 3.18 mm (0.13”) thick. Increasing the number of layers can result in even thicker circuit boards, which also increases cost and complexity. For example, for a patch offset 122 of several millimeters, antenna element 1500 can be manufactured more easily than antenna element 800.

[0061] Another advantage of the AOA antenna array 1700 is that it can be constructed using air as the dielectric within each antenna element 1500 (i.e., directly between each antenna patch 104 and the corresponding ground patch 102), which advantageously reduces losses compared to solid dielectrics. Alternatively, dielectrics other than those typically used for PCBs, such as crystalline silicon, sapphire, and glass, can be used. The solid dielectric within the antenna element 1500 improves its mechanical rigidity compared to air, thus making the AOA antenna array 1700 more robust for field-deployable operation.

[0062] Figures 18 to 20 Show Figure 15 How the antenna element 1500 can form different angles relative to the ground patch 102 and the system ground plane 108. Figures 18 to 20 In this configuration, antenna patch 104 is parallel to ground patch 102, positioned directly above ground patch 102 in the z-direction, and coplanar with system ground plane 108. The plane of short-circuit wall 1506 forms an angle θ with the plane of ground patch 102, and therefore a complementary angle 180°-θ with the plane of system ground plane 108. Figure 18 In this context, angle θ is 90°, meaning the short-circuit wall 1506 is perpendicular to the grounding patch 102 and the system grounding plane 108. Figure 19 In this context, angle θ is an acute angle. Figure 20 In this context, angle θ is an obtuse angle. Although Figures 18 to 20 The sixth edge 132 is shown to be connected to the second edge 126, but the short-circuit wall 1506 and the antenna patch 104 can be translated in the x-direction so that the sixth edge 132 is fully connected to the system ground plane 108 or fully connected to the ground patch 102.

[0063] In the preceding discussion, the system ground plane 108 was described as having: a first ground plane edge 304 forming a straight line in a first direction; and a second ground plane edge 306 forming a straight line in a second direction. In these embodiments, the first edges 124 of the antenna elements 100 of the first linear array are collinear and parallel to the first direction. The first edge 124 of the antenna elements 100 of the second linear array is also referred to herein as a third edge. The third edge is collinear and parallel to the second direction. Here, "collinear" means that, when extended in space, the first edge 124 of one antenna element 100 will coincide with the first edge 124 of every other antenna element 100 of the first linear array. Similarly, when extended in space, the third edge of one antenna element 100 will coincide with the third edge of every other antenna element 100 of the second linear array. However, without departing from the scope of this document, the first edge 124 of the first linear array may be non-collinear (e.g., parallel or skewed). Similarly, without departing from the scope of this document, the third edge of the second linear array may be non-collinear.

[0064] The second edge 126 of the antenna element 100 of the first linear array may be collinear, parallel to the first direction, and coincident with the edge 304 of the first ground plane. The second edge 126 of the antenna element 100 of the second linear array is also referred to herein as the fourth edge. The fourth edge may also be collinear, parallel to the second direction, and coincident with the edge 306 of the second ground plane. However, without departing from the scope of this document, the second edge 126 of the first linear array may be non-collinear. Similarly, without departing from the scope of this document, the fourth edge of the second linear array may be non-collinear.

[0065] The fifth edge 130 of the antenna element 100 of the first linear array may be collinear and parallel to the first direction. The fifth edge 130 of the antenna element 100 of the second linear array is also referred to herein as the seventh edge. The seventh edge may also be collinear and parallel to the second direction. However, without departing from the scope of this document, the fifth edge 130 of the first linear array may be non-collinear. Similarly, without departing from the scope of this document, the seventh edge of the second linear array may be non-collinear.

[0066] The sixth edge 132 of the antenna element 100 of the first linear array may be collinear, parallel to the first direction and coinciding with the edge 304 of the first ground plane. The sixth edge 132 of the antenna element 100 of the second linear array is also referred to herein as the eighth edge. The eighth edge may also be collinear, parallel to the second direction and coinciding with the edge 306 of the second ground plane. However, without departing from the scope of this document, the sixth edge 132 of the first linear array may be non-collinear. Similarly, without departing from the scope of this document, the eighth edge of the second linear array may be non-collinear.

[0067] In other embodiments, one or both of the first ground plane edge 304 and the second ground plane edge 306 are curved. Therefore, the ground plane edges 304 and 306 need not be straight. In these embodiments, the first and second edges can be similarly curved to align with the curved first ground plane edge 304. Similarly, the third and fourth edges can be curved to align with the curved second ground plane edge 306. In some embodiments, the first ground plane edge 304 and the second ground plane edge 306 are not orthogonal to each other. For example, the first ground plane edge 304 and the second ground plane edge 306 may form an acute or obtuse angle.

[0068] In the preceding discussion, antenna elements 100, 800, and 1500 were described as rectangular. Specifically, each antenna patch 104 and ground patch 102 is rectangular. However, without departing from the scope of this document, each antenna patch 104 and ground patch 102 may have different shapes. For example, antenna patches 104 and ground patches 102 may be semi-circular, triangular, or hexagonal. Antenna patches 104 and ground patches 102 may have similar geometries. More generally, antenna patches 104 and ground patches 102 may be congruent. All antenna elements within an AOA antenna array may have the same geometry (e.g., see...). Figure 3 Alternatively, an AOA antenna array may include antenna elements with different geometries. For example, the antenna elements of a linear array may all have a first geometry, while the antenna elements of a second linear array may all have a second geometry different from the first geometry.

[0069] Modifications to the methods and systems described above may be made without departing from the scope of this document. Therefore, it should be noted that the content contained in the above specification or shown in the accompanying drawings should be interpreted illustratively rather than restrictively. The following claims are intended to cover all general and specific features described herein, and all statements regarding the scope of this method and system may be said to fall within its language.

Claims

1. An angle-of-arrival antenna system, comprising: A first antenna element array along a first direction, each first antenna element having a first antenna patch positioned above a corresponding first ground patch, the first edge of the first antenna patch being parallel to the first direction, and the second edge of the first ground patch being parallel to the first direction and electrically connected to the first edge; Along a second antenna element array along a second direction orthogonal to the first direction, each second antenna element has a second antenna patch positioned above a corresponding second ground patch, the third edge of the second antenna patch being parallel to the second direction, and the fourth edge of the second ground patch being parallel to the second direction and electrically connected to the third edge; as well as The system ground plane has: (i) a first ground plane edge that is parallel to the first direction and directly electrically connected to each of the second edges, and (ii) a second ground plane edge that is parallel to the second direction and directly electrically connected to each of the fourth edges; A first short-circuit wall for each first antenna element, the first short-circuit wall having opposing fifth and sixth edges parallel to the first direction, the first edge and the fifth edge being directly electrically connected, and the second edge and the sixth edge being directly electrically connected; as well as A second short-circuit wall for each second antenna element, the second short-circuit wall having opposing seventh and eighth edges parallel to the second direction, the third edge being directly electrically connected to the seventh edge, and the fourth edge being directly electrically connected to the eighth edge.

2. The angle-of-arrival antenna system according to claim 1, wherein: The first antenna element array has two first antenna elements; and This second antenna element array has two second antenna elements.

3. The angle-of-arrival antenna system according to claim 1, wherein: The first antenna element array has three first antenna elements; and This second antenna element array has three second antenna elements.

4. The angle-of-arrival antenna system according to claim 1, wherein the ground plane of the system is coplanar with each first ground patch and each second ground patch.

5. The angle-of-arrival antenna system according to claim 1, These first antenna elements are equally spaced along the first direction at a first spacing less than half the center wavelength; and These second antenna elements are spaced equally along the second direction with a second spacing less than half the center wavelength.

6. The angle-of-arrival antenna system according to claim 1, further comprising a solid dielectric material between each first antenna patch and its corresponding first ground patch and between each second antenna patch and its corresponding second ground patch.

7. The angle-of-arrival antenna system of claim 1, further comprising air between each first antenna patch and its corresponding first ground patch and between each second antenna patch and its corresponding second ground patch.

8. The angle-of-arrival antenna system according to claim 1, wherein: Each first antenna patch is parallel to its corresponding first ground patch; and Each second ground patch is parallel to its corresponding second ground patch.

9. The angle-of-arrival antenna system according to claim 1, wherein: Each first antenna patch and its corresponding first ground patch have similar geometric shapes; and Each second antenna patch and its corresponding second ground patch have similar geometry.

10. The angle-of-arrival antenna system of claim 9, wherein the similar geometry is selected from the group consisting of: semicircle, rectangle, triangle and hexagon.

11. The angle-of-arrival antenna system according to claim 1, wherein: These first edges are collinear; These second edges are collinear; These third edges are collinear; and These fourth edges are collinear.

12. The angle-of-arrival antenna system according to claim 1, wherein: These fifth edges are collinear; These sixth edges are collinear; These seventh edges are collinear; and These eighth edge edges are collinear.

13. The angle-of-arrival antenna system according to claim 1, wherein: Each first short-circuit wall is perpendicular to its corresponding first antenna patch and the first patch is grounded; and Each second short-circuit wall is perpendicular to its corresponding second antenna patch and second patch ground.

14. The angle-of-arrival antenna system according to claim 1, further comprising: For each first antenna element in the first antenna element array: A first antenna feed, which passes through a first ground patch of each first antenna element and is directly electrically connected to a first antenna patch of each first antenna element; as well as For each second-day antenna element in this second-day antenna element array: The second antenna feed passes through the second ground patch of each of the second antenna elements and is directly electrically connected to the second antenna patch of each of the second antenna elements.

15. The angle-of-arrival antenna system of claim 1, further comprising a circuit board having multiple layers, wherein: Each first antenna patch and second antenna patch includes metal disposed on the first layer of the plurality of layers; Each first grounding patch and second grounding patch includes metal disposed on the second layer of the plurality of layers; and The system's grounding plane includes metal disposed on this second layer.

16. The angle-of-arrival antenna system of claim 15, further comprising: For each first antenna element in the first antenna element array: The first transmission line is set on the third layer of these multiple layers; as well as A first feed via passing through all of the multiple layers directly electrically connects the first transmission line to the first antenna patch of each of the first antenna elements; The first ground patch of each first antenna element forms a non-conductive ring around the first feed via, such that the first feed via is not shorted to the first ground patch; as well as For each second-day antenna element in this second-day antenna element array: A second transmission line is set on the third layer of these multiple layers; as well as A second feed via passes through all of the multiple layers, directly electrically connecting the second transmission line to the second antenna patch of each of the second antenna elements; The second ground patch of each second antenna element forms a non-conductive via around the second feed via, such that the second feed via is not shorted to the second ground patch.

17. The angle-of-arrival antenna system of claim 16, further comprising a switch soldered to a circuit board such that each input of the switch is electrically connected to a first transmission line or a second transmission line.

18. The angle-of-arrival antenna system of claim 16, further comprising: An array of vias passing through all of the multiple layers to electrically connect the first and second edges of each first antenna element; as well as An array of vias passing through all of the multiple layers to electrically connect the third and fourth edges of each second antenna element.

19. The angle-of-arrival antenna system of claim 15, further comprising: For each first antenna element in the first antenna element array: Collinear first and second via arrays, which pass through all layers of the plurality of layers to electrically connect the first and second edges of each first antenna element; A first transmission line is disposed on the third layer of the plurality of layers and passes through a first gap between the collinear first via array and second via array; as well as A first feed via passes through all of the plurality of layers and directly electrically connects the first transmission line to the first antenna patch of each of the first antenna elements; and For each second-day antenna element in this second-day antenna element array: Collinear third and fourth via arrays, which pass through all layers of the plurality of layers to electrically connect the third and fourth edges of each second antenna element; A second transmission line is disposed on the third layer and passes through the second gap between the collinear third and fourth via arrays; as well as The second feed via passes through all of the plurality of layers and directly electrically connects the second transmission line to the second antenna patch of each of the second antenna elements.

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