Dual-band patch antenna for angle-of-arrival analysis

Abstract

A dual-mode antenna array (300) receives RF signaling (104) for AoA analysis and includes a substrate (302), a ground plane (402) disposed at a first side, and a pair of radiating elements (308-1, 308-2) disposed at a second side. Each radiating element in the pair includes a conductive material arranged in a modified rectangular shape having a first slot (318) on the first side, a second slot (320) on the second side, a third slot (322) on the third side, and a fourth slot (324) on the fourth side. The antenna array further includes a feed probe (310) disposed adjacent to the radiating element pair and a pair of feed lines (314-1, 314-2), each feed line being conductively connected to the feed probe at a first end and conductively connected to each of a first feed point (341) and a second feed point (342) of a corresponding radiating element at a second end.

Description

Background Art

[0001] Wireless systems often employ techniques based on analysis of received radio frequency (RF) signals to determine the location of one wireless device relative to another. This location information may be used in beamforming techniques for device or user authentication or other security considerations. Such techniques typically rely on two analyses: time-of-flight (ToF) analysis and angle-of-arrival (AoA) analysis. ToF analysis uses the measurement of the elapsed time between the transmission of an RF signal and the reception of a reply RF signal to determine the distance between the initiating and responding devices. AoA analysis estimates the direction from which the incoming RF signal was received to determine the angular position of the transmitting device relative to the receiving device. Given the distance and angular position, the location of one wireless device relative to another can be determined.

[0002] Ultra-wideband (UWB)-based RF technology is often well-suited for use in providing AoA analysis in wireless systems where wireless devices are in relatively close proximity, i.e., within a personal area network (PAN). UWB signaling is relatively efficient because it typically relies on pulsed signals of relatively short duration, and because such signaling is transmitted over a relatively wide bandwidth (e.g., 500 megahertz (MHz)), UWB signaling can share the spectrum with other wireless devices. In a typical approach to using UWB signaling for AoA analysis, a transmitting device employs UWB signaling in one or more separate frequency bands that are orthogonally polarized relative to each other (e.g., one UWB band polarized in the horizontal direction and one UWB band polarized in the vertical direction). A receiving device employs an AoA antenna array to concurrently receive UWB signals in each of the utilized frequency bands and determines one or more AoA parameters from the one or more received RF signals.

[0003] To illustrate, Figure 1A typical time-difference-of-flight (TDOF)-based AoA analysis using an antenna array 100 having two identical rectangular patch antennas 101 and 102 offset by a distance "d" is depicted. An incoming RF signal 104 arriving at a non-zero angle θ relative to the boresight of the antenna array 100 (in this case, the Z-axis) is received at each of the rectangular patch antennas 101 and 102. However, because the RF signal 104 is received at the illustrated non-zero angle, the distance the RF signal 104 travels to reach patch antenna 101 is greater than the distance it travels to reach patch antenna 102, where this distance is equal to k*d*sin(θ), where k represents the wave number of the RF signal 104 in the respective media. Thus, there is a time offset between when the RF signal 104 is received at patch antenna 102 and when the RF signal 104 is received at patch antenna 101. This time offset introduces an AoA-related phase difference between the different representations of the RF signal 104 as received at the antennas 101 , 102 , and this phase difference can therefore be used to estimate the AoA of the RF signal 104 .

[0004] As Figure 2 As illustrated in graph 200 of Figure 200 , the AoA-related phase difference of an AoA antenna array is ideally expressed as k*d*sin(θ), which allows a system implementing such an AoA antenna array to determine the angle of arrival θ of an incoming RF signal based on the specific phase difference between the two received signals and the expression k*d*sin(θ). For accurate angle-of-arrival calculation, the phase difference between the two AoA signals ideally arises solely from path differences. This condition is generally satisfied when both AoA antennas have identical phase patterns (which eliminates any structure-related phase differences between the two measured AoA signals) and when both AoA antennas have uniform amplitude patterns (such that the antennas are suitable for all angles and have no nulls at one or more angles).

[0005] Patch antennas are theoretically well suited to satisfying the conditions identified above. They often have substantially uniform amplitude and phase patterns. However, in practice, conventional AoA antenna arrays do not exhibit this ideal phase relationship, particularly as a result of asymmetries between the antennas due to mismatches in the feed structures between the two antennas and other causes. Furthermore, the increasing miniaturization of user devices has resulted in device form factors that often cannot practically accommodate the relatively large size of conventional UWB-based AoA antenna arrays, either as a result of their relatively large floor plan area due to the size of the conventional rectangular patch antennas they employ, or their relatively thick profile due to either or both of the utilization of three-dimensional antenna structures or the relatively thick substrates required to implement conventional patch antenna shapes. Summary of the Invention

[0006] A dual-mode antenna array configured to receive radio frequency (RF) signaling for angle of arrival (AoA) analysis is provided, the antenna array comprising: a substrate; a ground plane disposed at a first side of the substrate; and a pair of radiating elements disposed at a second side of the substrate opposite the first side and separated by a lateral distance, each radiating element in the pair comprising: a conductive material arranged in a rectangular shape having a first slot at a first side, a second slot at a second side opposite the first side, a third slot at a third side, and a fourth slot at a fourth side opposite the third side, wherein the modified rectangular shape is obtained by arranging the first, second, third, and fourth slots. The first, second, third, and / or fourth sides may extend substantially straight.

[0007] The first slot and the second slot each may have a depth such that a length of a perimeter of the modified rectangular shape at each of the first side and the second side is at least equal to half a wavelength of a center frequency of a first frequency band in the received RF signaling; and / or the third slot and the fourth slot each may have a depth such that a length of a perimeter of the modified rectangular shape at each of the third side and the fourth side is at least equal to half a wavelength of a center frequency of a second frequency band in the received RF signaling, wherein, for example, the second frequency band is orthogonally polarized relative to the first frequency band.

[0008] In addition, the dual-mode antenna array may include: a feed probe, which is arranged at the second edge of the substrate and adjacent to the pair of radiating elements; a first microstrip feed line, which is conductively connected to the feed probe at a first end and conductively connected to the first radiating element at a second end at each of the first feeding point and the second feeding point of the first radiating element in the pair of radiating elements; and / or a second microstrip feed line, which is conductively connected to the feed probe at a first end and conductively connected to the second radiating element at a second end at each of the third feeding point and the fourth feeding point of the second radiating element in the pair of radiating elements, wherein the third feeding point and the fourth feeding point have, for example, positions on the second radiating element corresponding to the positions of the first feeding point and the second feeding point of the first radiating element, respectively.

[0009] In addition, the length of the first microstrip feed line between the feed probe and the first feed point may be substantially equal to the length of the second feed line between the feed probe and the third feed point; and / or the length of the first microstrip feed line between the feed probe and the second feed point may be substantially equal to the length of the second feed line between the feed probe and the fourth feed point.

[0010] The first feed point, the second feed point, the third feed point, and the fourth feed point may have substantially equal impedance.

[0011] The feeding probe may be disposed between the first radiating element and the second radiating element.

[0012] The feeding probe may be disposed adjacent to a colinear edge of the first radiating element and the second radiating element.

[0013] The first microstrip feed line may be conductively coupled to the first feed point and the second feed point using conductive vias; and / or the second microstrip feed line may be conductively coupled to the third feed point and the fourth feed point using conductive vias.

[0014] For example, the lateral distance is no greater than half a wavelength of the higher of the center frequency of the first frequency band and the center frequency of the second frequency band.

[0015] Furthermore, the length of each of the first side and the second side may be less than the wavelength of the center frequency of the first frequency band in the material of the substrate; and / or the length of each of the third side and the fourth side may be less than the wavelength of the center frequency of the second frequency band in the material of the substrate. The length of the first side and the second side may be defined by the distance between the third side and the fourth side, and the length of the third side and the fourth side may be defined by the distance between the first side and the second side.

[0016] The center frequency of the first frequency band may be 6.5 gigahertz (GHz); and / or the center frequency of the second frequency band may be 8 GHz; and / or the length of each of the first side and the second side may be less than 13.3 millimeters (mm); and / or the length of each of the third side and the fourth side may be less than 10.8 mm.

[0017] In addition, the center frequency of the first frequency band may be 6.5 gigahertz (GHz); and / or the center frequency of the second frequency band may be 8 GHz; and / or the depth of each of the first groove and the second groove is approximately 1.05 millimeters (mm), and / or the width of each of the first groove and the second groove is approximately 1.0 mm; and / or the depth of each of the third groove and the fourth groove is approximately 3.45 mm, and / or the width of each of the third groove and the fourth groove is approximately 1.0 mm; and / or the length of each of the first side and the second side is approximately 10.1 mm; and / or the length of each of the third side and the fourth side is approximately 8.2 mm.

[0018] For example, the thickness of the substrate between the first side and the opposite second side is no more than 0.4 mm.

[0019] In another aspect, a dual-mode antenna array configured to receive radio frequency (RF) signaling for angle of arrival (AoA) analysis is provided, in particular as described above, the antenna array comprising: a feed probe disposed at a first surface of a substrate; a first radiating element and a second radiating element disposed adjacent to the feed probe at the first surface of the substrate; and a feed structure electrically coupling the first radiating element and the second radiating element to the feed probe, the feed structure comprising: a first microstrip feed line connected to the feed probe at a first end and to a first feed point and a second feed point of the first radiating element at a second end; and a second microstrip feed line connected to the feed probe at a first end and to a third feed point and a fourth feed point of the second radiating element at a second end; and the positioning of the first feed point and the second feed point on the first radiating element is correspondingly the same as the positioning of the third feed point and the fourth feed point on the second radiating element (e.g., on the conductive material arranged in the rectangular shape of the radiating element as described above). The positioning of the feed point may be defined relative to a corresponding reference point of the radiating element, such as a corner or another point of the perimeter of the radiating element, in particular of the rectangular shape.

[0020] The first microstrip feed line and the second microstrip feed line may have substantially equal lengths.

[0021] In addition, the length of the first microstrip feed line between the feed probe and the first feed point may be substantially equal to the length of the second feed line between the feed probe and the third feed point; and / or the length of the first microstrip feed line between the feed probe and the second feed point may be substantially equal to the length of the second feed line between the feed probe and the fourth feed point.

[0022] Furthermore, the first feed point, the second feed point, the third feed point, and the fourth feed point may have substantially equal impedances.

[0023] The feeding probe may be disposed between the first radiating element and the second radiating element.

[0024] The feeding probe may be disposed adjacent to a colinear edge of the first radiating element and the second radiating element.

[0025] The first microstrip feed line may be conductively coupled to the first feed point and the second feed point using conductive vias; and / or the second microstrip feed line may be conductively coupled to the third feed point and the fourth feed point using conductive vias.

[0026] In addition, an electronic device is provided, which includes the dual-mode antenna array as described above.

[0027] The electronic device may include: an RF receiver conductively coupled to the feed probe and configured to process RF signaling received at the dual-band antenna array; and / or a baseband processor coupled to the RF receiver and configured to determine one or more AoA parameters from the RF signaling received at the dual-band antenna array and processed by the RF receiver.

[0028] In addition, a method of operating an electronic device is provided, comprising: receiving a first representation of a first RF signal of RF signaling at a first radiating element in a pair of radiating antenna elements, and receiving a second representation of the first RF signal of the RF signaling at a second radiating element in the pair of radiating antenna elements; and determining a first AoA parameter based on a phase difference between the first representation and the second representation of the first RF signal.

[0029] The method may include receiving a first representation of a second RF signal of the RF signaling at the first radiating element and receiving a second representation of the second RF signal of the RF signaling at the second radiating element; and determining a second AoA parameter based on a phase difference between the first and second representations of the second RF signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present disclosure may be understood and its numerous features and advantages become apparent to those skilled in the art by referring to the accompanying drawings.The use of the same reference numbers in different drawings indicates similar or identical items.

[0031] Figure 1 is a block diagram illustrating a typical time delay of flight (TDOF) method for calculating the angle of arrival (AoA) of an incoming radio frequency (RF) signal.

[0032] Figure 2 is a graph illustrating the ideal relationship between the phase difference of a received representation of an RF signal versus the AoA of the RF signal.

[0033] Figure 3 is a diagram illustrating a top view of a dual-mode AoA antenna array according to some embodiments.

[0034] Figure 4 is a diagram illustrating a method according to some embodiments Figure 3 Figure 2 is a cross-sectional view of a dual-mode AoA antenna array.

[0035] Figure 5 is a diagram illustrating a top view of an alternative implementation of a dual-mode AoA antenna utilizing edge-adjacent feed probes in accordance with some embodiments.

[0036] Figure 6 is a graph illustrating the difference in phase patterns of two modes of an example simulated implementation of a dual-mode AoA antenna array in accordance with some embodiments.

[0037] Figure 7 is a diagram illustrating a wireless system with an electronic device that utilizes a dual-mode AoA antenna array for performing AoA analysis on received RF signals in accordance with some embodiments. DETAILED DESCRIPTION

[0038] Many conventional AoA antenna arrays that are configured to operate with high-frequency, high-bandwidth signaling and exhibit sufficient linearity in their phase difference often have dimensions that make them difficult to integrate into many compact electronic devices. In contrast, described herein are embodiments of a dual-band AoA antenna array that employs dual antennas having a radiating patch shape that facilitates compact implementation in any of a variety of electronic devices. Furthermore, in some embodiments, the dual-band AoA antenna further employs a symmetrical feed structure that maintains substantial symmetry between the antennas of the antenna array, thereby facilitating a more linear AoA-related phase difference pattern between the antennas of the antenna array.

[0039] Figure 3 and Figure 4Together, a dual-mode antenna array 300 is illustrated, configured to facilitate AoA analysis of incoming RF signals, in accordance with some embodiments. Figure 3 depicts a top view of the dual-mode antenna array 300 in the XY plane, and Figure 4 Depicts a cross-sectional view of the dual-mode antenna array 300 along line AA in the XZ plane. Note that Figure 4 In the cross-sectional view of the antenna array 300, the dimensions of some components along the Z-axis are exaggerated to facilitate their depiction and understanding. As shown, the dual-mode antenna array 300 (hereinafter referred to as "antenna array 300" for the sake of brevity) includes a dielectric substrate 302 having a first major surface 304 and an opposing second major surface 306. The dielectric substrate 302 can be implemented as, for example, a rigid or flexible printed circuit board (PBC) and can be composed of any one or a combination of various dielectric materials such as liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), various ceramics, various low-loss plastics, glass-reinforced epoxy laminate (e.g., FR-4), etc.

[0040] The antenna array 300 further includes a ground plane 402 disposed at the main surface 306 of the substrate 302 ( Figure 4 ), and a pair of radiating elements 308, individually identified herein as radiating element 308-1 and radiating element 308-2, and a feed probe 310 disposed at opposing major surfaces 304. Feed structure 312 includes microstrip feed lines 314-1 and 314-2 that electrically couple feed probe 310 to radiating elements 308-1 and 308-2, respectively. Ground plane 402, radiating elements 308, feed probe 310, and feed structure 312 are composed of one or more conductive materials such as copper (Cu), gold (Au), silver (Ag), aluminum (Al), or alloys thereof, and each component can be composed of the same or different conductive materials, or a combination thereof. These structures can be disposed at corresponding surfaces of substrate 302 in any of a variety of ways, including by deposition, etching, attachment of a film or foil, or a combination thereof.

[0041] As described in greater detail below, radiating elements 308-1, 308-2 are configured to operate as a pair of receiver antennas to receive RF signaling and determine the angle of arrival (AoA) of the RF signaling relative to the boresight or other reference axis of antenna array 300 from a phase difference between a representation of the RF signaling received at radiating element 308-1 and a representation of the RF signaling received at radiating element 308-2. Accordingly, to facilitate efficient operation in this regard, in some embodiments, radiating elements 308-1, 308-2 are separated laterally (along the X-axis) by a distance 316 (center-to-center) that is no greater than half the wavelength λ in air of the highest center frequency that antenna array 300 is configured to support (i.e., distance 316 <= λ). For example, for a highest center frequency of 8 GHz, the center-to-center distance between radiating elements 308-1, 308-2 can be set to 18 mm, which is close to, but not exceeding, the 18.75 mm half-wavelength of an 8 GHz RF signal. By configuring distance 316 to be close to, but not exceeding, a half-wavelength, radiating elements 308-1, 308-2 are able to more easily and accurately measure phase differences between ±180 degrees (thereby improving robustness) while mitigating or eliminating the possibility of phase wrappings at higher frequencies.

[0042] As also described in more detail below, in at least some embodiments, the radiating elements 308-1, 308-2 are configured to support dual-mode operation and thereby provide polarization diversity, such that the radiating elements 308-1, 308-2 can be implemented to efficiently receive first RF signaling having a first center frequency and a first polarization and to receive second RF signaling having a second center frequency and a second polarization orthogonal to the first polarization. For example, the antenna array 300 can be configured to support operation of both UWB channel 5 (center frequency 6.5 GHz, 500 MHz bandwidth, vertical polarization) and UWB channel 9 (center frequency 8 GHz, 500 MHz bandwidth, horizontal polarization). For ease of description, this example UWB channel 5 / channel 9 configuration is frequently referenced below, but it should be understood that this configuration is merely an example and the antenna array 300 can be configured to support different combinations of orthogonally polarized UWB channels, as well as to support dual-mode operation in other high-frequency bands / channels unrelated to UWB, using the guidance provided herein. Therefore, unless otherwise indicated, references to UWB or to the specific UWB channel 5 / channel 9 embodiments described above should be understood to be equally applicable to other frequency bands / channels or to other RF technologies altogether.

[0043] To operate efficiently to support TDOF-based AoA analysis of received RF signaling, in at least one embodiment, the radiating elements 308-1, 308-2 are configured to be substantially identical, that is, to have approximately equal dimensions and composition, and the feed structure 312 is configured to be substantially symmetrical with respect to the feed probe 310 and the radiating elements 308-1, 308-2. Subject to practical limitations of the processes employed to design and manufacture the antenna array 300, achieving this symmetry mitigates any phase pattern differences that would otherwise arise between the radiating elements 308-1, 308-2 when receiving an incoming RF signal, thereby resulting in a more linear and reversible relationship between the AoA and the phase difference pattern for the TDOF representation of the incoming RF signal.

[0044] In order to efficiently provide dual-mode operation for orthogonally polarized RF signals, the radiating elements 308-1, 308-2 utilize a generally rectangular patch shape to provide a half-wavelength current path for the vertically polarized RF signals while also providing a half-wavelength current path for the horizontally polarized RF signals. However, in some embodiments, using an unmodified rectangular area for each radiating element results in a relatively large floor plan area for each radiating element, thereby resulting in a total floor plan area for the antenna array 300 that is too large to be practically implemented in many compact electronic devices such as smart watches, key fobs, cell phones, RF modules for vehicles, and the like. Therefore, in some embodiments, the conductive layers implementing the radiating elements 308-1, 308-2 are each formed to have a modified rectangular patch shape, wherein each side of the resulting generally rectangular area of ​​conductive material has at least one slot extending toward the center of the radiating element and being substantially free of conductive material. To illustrate, in Figure 3 In the depicted embodiment, radiating element 308-1 is comprised of copper or other conductive material arranged in a modified rectangular shape, with slot 318-1 on edge 319, slot 320-1 on the opposite edge 321, slot 322-1 on edge 323, and slot 324-1 on the opposite edge 325. Slots 318-1 and 320-1 extend in the Y direction from the corresponding patch edges 321, 323 toward the center of the modified rectangular shape, while slots 322-1 and 324-1 extend from the corresponding patch edges 323, 325 toward the center of the modified rectangular shape. In some embodiments, for symmetry, opposing slots are centered about their corresponding edges and have substantially the same dimensions (depth and width), but in other embodiments, opposing slots may have different dimensions, may be offset relative to the center of the corresponding edge, or a combination thereof. Consistent with implementing radiating element 308 so as to be substantially identical in size and composition, radiating element 308-2 similarly has slots 318-2, 320-2, 322-2, and 324-2 on its respective sides, with the positions and dimensions corresponding to those of slots 318-1, 320-1, 322-1, and 324-1, respectively.

[0045] The presence of a slot in an otherwise rectangular shaped side of the patch radiating element increases the effective length of the perimeter of that side of the patch radiating element, thereby increasing the current path "length" of that side to be greater than the linear length of that side for the purpose of resonance of a received RF signal polarized in a direction parallel to that side. This in turn allows the total or linear dimension of that side of the rectangular shape to be reduced to less than half the wavelength of the received RF signal for the composition of the underlying substrate 302 while still providing a half-wavelength current path. For illustration, a UWB channel 5 having a center frequency of 6.5 GHz and having a polarization orientation 330 at Figure 3 An RF signal parallel to the Y-axis in the depicted orientation has a half-wavelength of 13.3 mm in the LCP substrate, and thus would require opposing sides of a regular rectangular patch radiating element to be at least 13.3 mm long in the Y-direction to provide a half-wavelength current path. Similarly, an RF signal in UWB channel 9 having a center frequency of 8 GHz and polarization orientation 332 parallel to the X-axis in the illustrated orientation has a half-wavelength of 10.8 mm in the LCP substrate, and thus would require opposing sides of a regular rectangular patch radiating element to be at least 10.8 mm long in the X-direction to provide a half-wavelength current path. In other words, an unmodified rectangular radiating element would need to be 13.3 mm long in the Y-direction and 10.8 mm wide in the X-direction to provide dual-mode resonance for both UWB channel 5 and UWB channel 9 when using an LCP substrate.

[0046] However, if, for example, the antenna array 300 were to employ the same LCP substrate and radiating elements 308-1, 308-2, wherein the slots 318-1, 318-2, 320-1, and 320-2 each had a depth (dimension 334) of 1.05 mm and a width (dimension 335) of 1.0 mm, and wherein the slots 322-1, 322-2, 324-1, and 324-2 each had a depth (dimension 336) of 3.45 mm and a width (dimension 337) of 1.0 mm, then the total length in the Y direction (dimension 338) and the total length in the X direction (dimension 339) of each radiating element 308-1, 308-2 could be reduced to 8.2 mm and 10.1 mm, respectively, while continuing to provide an effective perimeter length of at least 13.3 mm in the Y direction and at least 10.8 mm in the X direction, thereby providing an effective current path length. That is, the presence and dimensions of the slots in radiating elements 308-1, 308-2 allow radiating elements 308-1, 308-2 to have overall dimensions (338, 339) that are less than the corresponding half-wavelength of the intended resonant frequency in the underlying substrate material while providing an effective side perimeter length, and thus allow the corresponding current path length to be at least equal to half a wavelength of the intended resonant frequency, thereby allowing radiating elements 108-1, 108-2 to resonate efficiently at the identified center frequencies of the channels that dual-mode antenna array 300 is designed to support. That is, by introducing the slots having the dimensions identified above, the overall dimensions of radiating element 308 can be reduced in this example from 13.3 mm x 10.8 mm (as required using the unmodified rectangular shape) to 10.3 mm x 8.2 mm (using the modified rectangular shape with the slots described above). Thus, where a smaller floor plan area is required for radiating elements 308-1, 308-2, the overall floor plan area of ​​antenna array 300 can likewise be reduced, thereby allowing the resulting antenna array 300 to be more easily implemented in smaller or more compact electronic devices.

[0047] From the above, it should be appreciated that increasing the depth of the relative slots allows for a proportional reduction in the total length of the sides of radiating element 308 that implement the relative slots. However, it should also be appreciated that the greater the reduction in the total length of the sides of radiating element 308, the less efficient the resonance of radiating element 308 will generally be for target RF signals polarized in the corresponding direction. Therefore, in practical implementations, the selection of the dimensions of radiating elements 308-1, 308-2 and the slots they contain may involve identifying an appropriate trade-off between floor plan area and overall antenna efficiency. To illustrate, in some examples, the maximum floor plan area may be fixed, and the maximum overall dimension of each radiating element 308 may likewise be fixed (particularly considering the nearly half-wavelength separation (distance 316) maintained between radiating elements 308-1, 308-2), with the slot dimensions thus selected with these fixed overall dimensions in mind. In other examples, a minimum efficiency for each mode may be specified, and the overall dimensions and slot dimensions may be selected based on these parameters, for example, through an iterative simulation and evaluation process.

[0048] As with many patch antennas, the center of radiating elements 308-1, 308-2 is not used as a feed point for connecting radiating elements 308-1, 308-2 to feed probe 310 due to the insufficient impedance presented at the center point. Instead, candidates for feed point locations in patch antennas are those points that present an impedance suitable for impedance matching with other components, which often means an impedance of approximately 50 ohms (Ω). Due to the four-lobed shape that is symmetrical about the X and Y axes resulting from implementing opposing slots on each of the four sides, each radiating element 308-1, 308-2 has four candidate feed points that provide a suitable impedance, which are illustrated as candidate feed points 341, 342, 343, and 344.

[0049] In a typical conventional feeding method, the same single feed point located on each radiating element 308 would be connected to the feed probe 310 via a corresponding microstrip feed line. For example, a first microstrip feed line would connect the feed point 341 of radiating element 308-1 to the feed probe 310, while a second microstrip feed line would connect the feed point 341 of radiating element 308-2 to the feed probe 310. However, due to the position of feed probe 310 between radiating elements 308-1 and 308-2 in this exemplary embodiment, feed point 341 of radiating element 308-2 is closer to feed probe 310 than feed point 341 of radiating element 308-1. As a result, the first microstrip line will be substantially longer than the second microstrip line, and this difference or asymmetry in the transmission line lengths in close proximity to the antennas, as required by conventional feeding methods, changes the behavior of the radiating elements 308-1, 308-2 relative to each other, thereby typically introducing nonlinear phase pattern differences and frequency shifts in the received representations of the incoming RF signal between the two antennas.

[0050] Therefore, to reduce or eliminate such asymmetry in the feed structure and thus mitigate nonlinear phase pattern differences and frequency shifts, in at least one embodiment, the feed structure 312 of the antenna array 300 is configured to provide symmetry with respect to the radiating elements 308-1, 308-2 by implementing microstrip feed lines 314-1, 314-2, each connected to an additional feed point, resulting in each feed line 314-1, 314-2 being connected to the feed probe 310 at one end and to two feed points at the other end. For example, in the illustrated Figure 3 and Figure 4 In the embodiment of FIG. 5 , the microstrip feed line 314 - 1 is connected at one end to the microstrip feed line 314 - 1 by a conductive via 404 (eg, epoxy) extending through a dielectric layer 406 (eg, epoxy). Figure 4 ) is connected to feed probe 310 at one end and to feed points 341 and 342 of radiating element 308-1 at the other end using conductive vias 408 and 410, respectively. Similarly, microstrip feed line 314-2 is connected to feed probe 310 at one end using conductive via 412 and to feed points 341 and 342 of radiating element 308-2 at the other end using conductive vias 414 and 416, respectively. Using this approach, microstrip feed lines 314-1, 314-2 can have substantially equal lengths, thereby providing the desired symmetry, and using a second feed point connection for each feed line also ensures that the current distribution remains substantially unchanged, thereby avoiding negatively impacting the operation of each radiating element 308. Furthermore, in the illustrated embodiment where the feed probe 310 is located between the two radiating elements 308 - 1 , 308 - 2 , the result is that the resulting received signal representations from the radiating elements 308 - 1 , 308 - 2 have a 180 degree phase difference, which can be easily calibrated and adjusted by a receiver component utilizing the antenna array 300 .

[0051] although Figure 3 and Figure 4 An example is shown in which the microstrip feed lines 314-1, 314-2 are connected to feed points 341, 342 in the corresponding radiating elements 308-1, 308-2, but the microstrip feed lines 314-1, 314-2 can instead be shifted in the Y direction and connected to feed points 343 and 344 on each radiating element 108. Furthermore, rather than being disposed between the two radiating elements 308, the feed probe 310 can instead be disposed adjacent to corresponding outer edges of the radiating elements 308-1, 308-2 (i.e., adjacent to collinear edges of the radiating elements 308-1, 308-2), as long as the same two corresponding feed points are used on each radiating element 308 and the lengths of the microstrip feed lines 314 are approximately equal and thus maintain symmetry. For illustration, Figure 5An alternative embodiment of the antenna array 300 is shown in which the feed probe 510 is parallel to the "top" collinear edges of the radiating elements 308-1, 308-2 ("top" is relative to the Figure 5 oriented in the view of FIG. 1 . Feed structure 512 includes microstrip feed lines 514-1 and 514-2. Microstrip feed line 514-1 is connected to feed probe 510 at one end and to feed points 342 and 344 of radiating element 308-1 at a second end (through conductive vias). Microstrip feed line 514-2 is similarly connected to feed probe 510 at one end and to feed points 342 and 344 of radiating element 308-2 at a second end. In this approach, microstrip feed lines 514-1 and 514-2 can have substantially equal lengths, and by virtue of these equal transmission line lengths and dual feed point connections, radiating elements 308-1, 308-2 in this configuration exhibit substantially similar responses, thereby maintaining substantially similar phase patterns and minimal or no shift.

[0052] Figure 6 The diagram depicts a simulation according to some embodiments. Figure 3 and Figure 4 Graphs showing phase pattern differences for an example embodiment of the antenna array 300. In this example, the antenna array 300 was simulated using the following relevant parameters:

[0053] Table 1: Simulation parameters

[0054] parameter: value: First Mode UWB channel 9 (8 GHz, 500 MHz bandwidth) Second Mode UWB channel 5 (6.5 GHz, 500 MHz bandwidth) Substrate material LCP Substrate thickness 0.4mm (Z direction) Lateral displacement (distance 316) 15mm center to center The total length of the radiating element 308 in the X direction (dimension 339) 10.1mm The total length of the radiating element 308 in the Y direction (dimension 338) 8.2mm Depth of grooves 318, 320 (dimension 334) 1.05mm Slots 318, 320 width (dimension 335) 1.0mm Depth of grooves 322, 324 (dimension 336) 3.45mm Slots 322, 324 width (dimension 337) 1.0mm

[0055] Graph 602 illustrates the resulting phase pattern difference versus angle of arrival (θ) for the first mode (UWB channel 9), and graph 604 illustrates the phase pattern difference versus angle of arrival (θ) for the second mode (UWB channel 5). As demonstrated, for angles of arrival (θ) between -60 degrees and +60 degrees across the entire 500 MHz bandwidth, the angle-dependent phase pattern difference is substantially linear for both modes. Table 2 below sets forth additional salient operational behavior obtained from the simulated implementation:

[0056] Table 2: Operational behavior

[0057] Behavior First Mode Second Mode Return loss >20dB >5dB Isolation >20dB >20dB Radiation efficiency -3dB -6.7dB System efficiency -2.8dB -7.9dB 10dB BW[MHz] 650 1000

[0058] Figure 71 shows a system 700 that employs a dual-mode antenna array 300 for AoA calculations in accordance with some embodiments. The system 700 includes a transmitting device 702 and a receiving device 704 separated by a distance no greater than the effective range of the corresponding RF technology employed, which is, in the example embodiment, UWB-based RF signaling. The receiving device 704 represents any of a variety of compact electronic devices, such as a smartwatch, a cell phone, a tablet computer, an RF subsystem of an automobile or other vehicle, an RF subsystem of a security system, etc. The receiving device 704 includes the antenna array 300, a feed probe 310 ( Figure 3 ), and a baseband processor 708 having one or more inputs coupled to the outputs of the RF receiver 706. The transmitting device 702 includes any of a variety of devices configured to transmit UWB signaling in one or more channels (e.g., channel 5 and channel 9) supported by the antenna array 300, such as a smart watch, a mobile phone, a key fob, a tablet computer, etc.

[0059] In operation, transmitting device 702 transmits an incoming RF signal 710, which is received by antenna array 300 of receiving device 704 at an angle θ relative to the boresight of antenna array 300. Therefore, this angle θ represents the AoA of incoming RF signal 710 from the perspective of receiving device 704. Due to this non-zero angle, there is a delay between when a representation of RF signal 710 is received at the left antenna, represented by radiating element 308-1, and when a representation of RF signal 710 is received at the right antenna, represented by radiating element 308-2, thereby introducing a phase difference between the two received representations of RF signal 710. Accordingly, RF receiver 706 receives these two time-shifted / phase-shifted representations of RF signal 710 as input, performs any of various pre-processing operations, such as various filtering operations, and provides an analog or digital representation of each received representation of RF signal 710 to baseband processor 708. Baseband processor 708 determines the phase difference between the two received representations and, based on the determined phase difference, determines one or more AoA estimates for incoming RF signal 710. For example, in one embodiment, the phase difference behavior of the antenna array 300 for a given pattern can be quantified and used to populate a lookup table (LUT) having the phase difference as input and the corresponding AoA estimate as output. An application processor (not shown) can then use the AoA estimate to locate the transmitting device 702 relative to the receiving device 704 in conjunction with any ranging information obtained about the transmitting device from a separate ranging process.

[0060] In some embodiments, certain aspects of the above-described technology can be implemented by one or more processors of a processing system that executes software. The software includes one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer-readable storage medium. The software can include instructions and certain data that, when executed by one or more processors, manipulate the one or more processors to perform one or more aspects of the above-described technology. The non-transitory computer-readable storage medium can include, for example, a magnetic or optical disk storage device, a solid-state storage device such as flash memory, a cache, a random access memory (RAM), or one or more other non-volatile memory devices. The executable instructions stored on the non-transitory computer-readable storage medium can be source code, assembly language code, object code, or other instruction formats that are interpreted or otherwise executable by one or more processors.

[0061] Note that not all of the activities or elements described above in the general description are required, a portion of a specific activity or device may not be required, and in addition to those described, one or more further activities may be performed or one or more further elements may be included. Furthermore, the order in which the activities are listed is not necessarily the order in which they are performed. In addition, the concepts have been described with reference to specific embodiments. However, it will be appreciated by those skilled in the art that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the appended claims. Therefore, the description and figures will be considered in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.

[0062] Beneficial effects, other advantages and solutions to problems have been described above with respect to specific embodiments. However, beneficial effects, advantages, solutions to problems, and any features that may make any beneficial effect, advantage, or solution occur or become more apparent should not be construed as key, required, or essential features of any or all of the claims. Furthermore, the specific embodiments disclosed above are merely illustrative, as the disclosed subject matter may be modified and implemented in different but equivalent manners that will be clear to those skilled in the art having the benefit of the teachings herein. No limitation is intended to the details of construction or design shown herein, except as described in the appended claims. It is therefore apparent that the specific embodiments disclosed above may be changed or modified, and all such variations are considered to be within the scope of the disclosed subject matter. Accordingly, the protection sought herein is as set forth in the appended claims.

Claims

1. A dual-mode antenna array configured to receive radio frequency (RF) signaling for angle of arrival (AoA) analysis, the dual-mode antenna array comprising: substrate; a ground plane disposed at a first side of the substrate; a pair of radiating elements disposed at a second edge of the substrate opposite the first edge, wherein the radiating elements of the pair are separated by a lateral distance, each radiating element of the pair comprising: a conductive material arranged in a modified rectangular shape having a first slot at a first side, a second slot at a second side opposite the first side, a third slot at a third side, and a fourth slot at a fourth side opposite the third side; a feeding probe disposed at the second side of the substrate and adjacent to the pair of radiating elements; and A first microstrip feed line is conductively connected to the feed probe at a first end and conductively connected to the first radiating element of the pair at each of a first feed point and a second feed point of the first radiating element at a second end.

2. The dual-mode antenna array according to claim 1, wherein: The first slot and the second slot each have a depth such that a length of a perimeter of the modified rectangular shape at each of the first side and the second side is at least equal to half a wavelength of a center frequency of a first frequency band in received RF signaling; and / or The third slot and the fourth slot each have a depth such that a length of the perimeter of the modified rectangular shape at each of the third side and the fourth side is at least equal to half a wavelength of a center frequency of a second frequency band in the received RF signaling, wherein the RF signaling in the second frequency band is orthogonally polarized relative to the RF signaling in the first frequency band.

3. The dual-mode antenna array according to claim 1, further comprising: a second microstrip feed line conductively connected at a first end to the feed probe and conductively connected at a second end to the second radiating element of the pair at each of a third feed point and a fourth feed point, the third feed point and the fourth feed point having positions on the second radiating element corresponding to the positions of the first feed point and the second feed point of the first radiating element, respectively.

4. The dual-mode antenna array according to claim 3, wherein: The length of the first microstrip feed line between the feed probe and the first feed point is substantially equal to the length of the second microstrip feed line between the feed probe and the third feed point; and / or A length of the first microstrip feed line between the feed probe and the second feed point is substantially equal to a length of the second microstrip feed line between the feed probe and the fourth feed point.

5. The dual-mode antenna array according to claim 3, wherein: The first feed point, the second feed point, the third feed point, and the fourth feed point have substantially equal impedances.

6. The dual-mode antenna array according to claim 3, wherein: The feeding probe is disposed between the first radiating element and the second radiating element.

7. The dual-mode antenna array according to claim 3, wherein: The feed probe is disposed adjacent to a colinear edge of the first radiating element and the second radiating element.

8. The dual-mode antenna array according to claim 3, wherein: conductively coupling the first microstrip feed line to the first feed point and the second feed point using conductive vias; and / or Conductive vias are used to conductively couple the second microstrip feed line to the third feed point and the fourth feed point.

9. The dual-mode antenna array according to claim 2, wherein: The lateral distance is no greater than half a wavelength of a higher of the center frequency of the first frequency band and the center frequency of the second frequency band.

10. The dual-mode antenna array according to claim 2, wherein: The length of each of the first side and the second side is less than the wavelength of the center frequency of the first frequency band in the material of the substrate, the length of the first side and the second side being defined by the distance between the third side and the fourth side; and / or Each of the third and fourth sides has a length less than a wavelength of the center frequency of the second frequency band in the material of the substrate, the length of the third and fourth sides being defined by a distance between the first and second sides.

11. The dual-mode antenna array according to claim 10, wherein: The center frequency of the first frequency band is 6.5 gigahertz (GHz); The center frequency of the second frequency band is 8 GHz; The length of each of the first side and the second side is less than 13.3 millimeters (mm); and A length of each of the third side and the fourth side is less than 10.8 mm.

12. The dual-mode antenna array according to claim 10, wherein: The center frequency of the first frequency band is 6.5 gigahertz (GHz); The center frequency of the second frequency band is 8 GHz; a depth of each of the first groove and the second groove being approximately 1.05 millimeters (mm), and a width of each of the first groove and the second groove being approximately 1.0 mm; a depth of each of the third groove and the fourth groove is approximately 3.45 mm, and a width of each of the third groove and the fourth groove is approximately 1.0 mm; The length of each of the first side and the second side is approximately 10.1 mm; and The length of each of the third side and the fourth side is approximately 8.2 mm.

13. The dual-mode antenna array according to claim 12, wherein: The thickness of the substrate between the first side and the opposite second side is no greater than 0.4 mm.

14. A dual-mode antenna array configured to receive radio frequency (RF) signaling for angle of arrival (AoA) analysis, the dual-mode antenna array comprising: a feeding probe disposed at the first surface of the substrate; a first radiating element and a second radiating element, wherein the first radiating element and the second radiating element are disposed adjacent to the feeding probe at the first surface of the substrate; as well as a feed structure electrically coupling the first radiating element and the second radiating element to the feed probe, the feed structure comprising: a first microstrip feed line connected at a first end to the feed probe and at a second end to a first feed point and a second feed point of the first radiating element; and a second microstrip feed line connected at a first end to the feed probe and at a second end to a third feed point and a fourth feed point of the second radiating element; and The positioning of the first and second feed points on the first radiating element is correspondingly the same as the positioning of the third and fourth feed points on the second radiating element.

15. The dual-mode antenna array according to claim 14, wherein: The first microstrip feed line and the second microstrip feed line have substantially equal lengths.

16. The dual-mode antenna array according to claim 14, wherein: The length of the first microstrip feed line between the feed probe and the first feed point is substantially equal to the length of the second microstrip feed line between the feed probe and the third feed point; and / or A length of the first microstrip feed line between the feed probe and the second feed point is substantially equal to a length of the second microstrip feed line between the feed probe and the fourth feed point.

17. The dual-mode antenna array according to claim 14, wherein: The first feed point, the second feed point, the third feed point, and the fourth feed point have substantially equal impedances.

18. The dual-mode antenna array according to claim 14, wherein: The feeding probe is disposed between the first radiating element and the second radiating element.

19. The dual-mode antenna array according to claim 14, wherein: The feed probe is disposed adjacent to a colinear edge of the first radiating element and the second radiating element.

20. The dual-mode antenna array according to any one of claims 14 to 19, wherein: conductively coupling the first microstrip feed line to the first feed point and the second feed point using conductive vias; and / or Conductive vias are used to conductively couple the second microstrip feed line to the third feed point and the fourth feed point.

21. An electronic device comprising the dual-mode antenna array according to any one of claims 1-20.

22. The electronic device according to claim 21, further comprising: an RF receiver conductively coupled to the feed probe and configured to process RF signaling received at the dual-mode antenna array; and / or A baseband processor is coupled to the RF receiver and is configured to determine one or more AoA parameters based on the RF signaling received at the dual-mode antenna array and processed by the RF receiver.

23. A method of operating an electronic device according to claim 21 or 22, comprising: receiving a first representation of a first RF signal of the RF signaling at a first radiating element of the pair, and receiving a second representation of the first RF signal of the RF signaling at a second radiating element of the pair; as well as A first AoA parameter is determined based on a phase difference between the first representation and the second representation of the first RF signal.

24. The method of operating the electronic device according to claim 23, further comprising: receiving a first representation of a second RF signal of the RF signaling at the first radiating element and receiving a second representation of the second RF signal of the RF signaling at the second radiating element; as well as A second AoA parameter is determined based on a phase difference between the first representation and the second representation of the second RF signal.

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