Patent Application
20220077594
This disclosure relates generally to radar, communication, and other systems. More specifically, this disclosure relates to a multi-beam passively-switched patch antenna array.
In some systems, antenna arrays are used to transmit different high-gain beams in different directions at different times. This may be useful in various applications, such as radars and communication systems. Some approaches use electronic beam steering to change the way in which input signals are provided to antenna arrays in order to modify how the antenna arrays transmit outgoing beams. Other approaches use active switching with field effect transistor (FET) switches combined with multiple phase-tapered splitters, where the switching action of the FETs changes which phase-tapered splitter receives the input signal and thereby changes the resulting beam angle.
This disclosure provides a multi-beam passively-switched patch antenna array.
In a first embodiment, an apparatus includes multiple patch antenna elements configured to transmit multiple electromagnetic beams in multiple beam directions. The apparatus also includes multiple inputs each configured to receive one of multiple input signals, where each input signal is associated with one of the electromagnetic beams. The apparatus further includes multiple phase-tapered splitters each configured to receive one of the input signals, divide the received input signal into a set of sub-signals, and provide a phase taper that adjusts phases of at least some of the sub-signals in the set of sub-signals. Different phase tapers are associated with different ones of the beam directions. In addition, the apparatus includes multiple 90° hybrid transformers each configured to receive sub-signals associated with different ones of the input signals, isolate the received sub-signals from each other, and provide the isolated sub-signals to one of the patch antenna elements.
In a second embodiment, a system includes at least one signal source and a multi-beam passively-switched patch antenna array. The at least one signal source is configured to generate multiple input signals. The patch antenna array includes multiple patch antenna elements configured to transmit multiple electromagnetic beams in multiple beam directions. The patch antenna array also includes multiple inputs each configured to receive one of the input signals, where each input signal is associated with one of the electromagnetic beams. The patch antenna array further includes multiple phase-tapered splitters each configured to receive one of the input signals, divide the received input signal into a set of sub-signals, and provide a phase taper that adjusts phases of at least some of the sub-signals in the set of sub-signals. Different phase tapers are associated with different ones of the beam directions. In addition, the patch antenna array includes multiple 90° hybrid transformers each configured to receive sub-signals associated with different ones of the input signals, isolate the received sub-signals from each other, and provide the isolated sub-signals to one of the patch antenna elements.
In a third embodiment, a method includes receiving a first input signal, dividing the first input signal into a first set of multiple sub-signals, and adjusting phases of at least some of the sub-signals in the first set of sub-signals according to a first phase taper. The method also includes feeding the phase-adjusted first set of sub-signals to multiple patch antenna elements through multiple 90° hybrid transformers and transmitting a first electromagnetic beam in a first beam direction using the patch antenna elements based on the phase-adjusted first set of sub-signals. The method further includes receiving a second input signal, dividing the second input signal into a second set of multiple sub-signals, and adjusting phases of at least some of the sub-signals in the second set of sub-signals according to a second phase taper. In addition, the method includes feeding the phase-adjusted second set of sub-signals to the patch antenna elements through the 90° hybrid transformers and transmitting a second electromagnetic beam in a second beam direction using the patch antenna elements based on the phase-adjusted second set of sub-signals. The 90° hybrid transformers isolate the first and second sets of sub-signals from each another. The first and second beam directions are based on the first and second phase tapers, respective.
Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
For a more complete understanding of this disclosure, reference is made to the following description, taken in conjunction with the accompanying drawings, in which:
As noted above, in some systems, antenna arrays are used to transmit different high-gain beams in different directions at different times. This may be useful in various applications, such as radars and communication systems. Some approaches use electronic beam steering to change the way in which input signals are provided to antenna arrays in order to modify how the antenna arrays transmit outgoing beams. Other approaches use active switching with field effect transistor (FET) switches combined with multiple phase-tapered splitters, where the switching action of the FETs changes which phase-tapered splitter receives the input signal and thereby changes the resulting beam angle. However, these approaches may require a considerable amount of space to be implemented, which can limit or prevent their use in volume-constrained applications. These approaches also often cannot be used with mono-pulse tracking or permit scaling to arbitrary antenna array sizes. Mono-pulse tracking is a technique used to encode radio frequency (RF) signals to provide accurate directional information, which may be needed or desired in certain applications.
This disclosure provides a multi-beam passively-switched patch antenna array. As described in more detail below, the multi-beam passively-switched patch antenna array includes an array of patch antenna elements and circuitry configured to provide different signals to different antenna elements of the array. The circuitry includes phase-tapered splitters that are used to divide each of multiple input signals into multiple sub-signals, where the sub-signals are provided to different antenna elements of the array. The phase tapering is designed to achieve a desired beam direction for one of multiple output beams produced by the array. The circuitry also includes hybrid transformers that isolate the sub-signals for different input signals from one another prior to reaching the antenna elements of the array. This enables a system to provide one input signal to the circuitry for use in transmitting a beam in a first desired direction and to provide another input signal to the circuitry for use in transmitting another beam in a second desired direction.
In this way, the multi-beam passively-switched patch antenna array supports the transmission of different beams in different directions in a compact package (such as a thin flat package). Moreover, this is accomplished passively in a manner that reduces or eliminates the need for electronic beam steering or active switching. Further, the patch antenna array can be used in mono-pulse tracking applications and can be scaled to arbitrary antenna array sizes. In addition, in some embodiments, the patch antenna array can be fabricated using common printed circuit board (PCB) materials, such as dielectric materials and etched metals, which can significantly reduce the cost and manufacturing requirements of the array.
One or more instances of the multi-beam passively-switched patch antenna array may be used in any suitable applications. Example applications can include various secure (high gain) communications applications, antennas used for seeker applications, and applications in drones or other flight vehicles. Other example applications can include automotive radar applications, such as forward-look and side-look beams in single passive package (utilizing two antennas, one on each side of the vehicle), or applications in 5G antennas (utilizing a semi- or non-gimbaled two-beam antenna for communications with two base stations).
As can be seen here, the patch antenna array 102 supports the ability to generate multiple high-gain beams 106a-106b, which are isolated and can be independently activated as described below. The ability to generate different high-gain beams 106a-106b and the ability to passively switch between transmitting the beams 106a-106b can be extremely useful in various applications. Moreover, the patch antenna array 102 supports these functions without requiring electronic beam forming or active switching, which can help to reduce the size, weight, and cost of the patch antenna array 102. Further, the patch antenna array 102 can be used with mono-pulse tracking applications or other applications. In addition, the patch antenna array 102 can independently generate multiple beams 106a-106b that are separated by a fixed angle within any suitable wavelength or frequency band(s).
In some embodiments, the patch antenna array 102 may represent a circular patch antenna array, and the beams 106a-106b may represent circularly-polarized beams. In particular embodiments, the beam 106a may have a “right hand” circular polarization, and the beam 106b may have a “left hand” circular polarization (or vice versa). Note, however, that other designs and operations of the patch antenna array 102 may be used.
In this example, the system 100 additionally includes at least one signal source 112 and a controller 114. The at least one signal source 112 represents a source of input electrical signals that are provided to the patch antenna array 102, where the input signals provide RF power used to generate the beams 106a-106b. A single source 112 may generate multiple input signals, or different sources 112 may generate different input signals. Each signal source 112 represents any suitable structure configured to generate RF power used to generate at least one beam of electromagnetic energy. The controller 114 controls the operation of the signal source(s) 112 in order to control which input signal is provided to the patch antenna array 102 at any given time. For instance, the controller 114 may cause one input signal to be provided to the patch antenna array 102 (so that a first beam 106a is produced) and then cause another input signal to be provided to the patch antenna array 102 (so that a second beam 106b is produced). The controller 114 may switch back and forth between the input signals as needed or desired. The controller 114 includes any suitable structure configured to control operation of at least part of the system 100. For example, the controller 114 may include one or more processing devices, such as one or more microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), or discrete elements.
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The patch antenna elements 202 are positioned over a stack 204 of additional layers. The stack 204 includes circuitry that can be used as described below to provide electrical signals to the patch antenna elements 202. The electrical signals can be processed using the circuitry in order to cause the patch antenna elements 202 to generate and radiate different beams 106a-106b in desired directions.
In some embodiments, the patch antenna array 102 may be divided into quadrants 206a-206d or other sections, and input signals can be provided to different quadrants of the patch antenna array 102 (although this need not be the case). In the example shown in
In this example, the patch antenna array 102 additionally includes at least one projection 208 extending from the stack 204. The projection 208 may be used to help ensure that the patch antenna array 102 is installed with a correct orientation in a larger device or system. For example, installing the patch antenna array 102 upside down or otherwise rotated in the system 100 of
While the patch antenna array 102 here is shown as having a generally flat circular disc shape, the patch antenna array 102 may have any other suitable form.
Also, the patch antenna array 102 may be packaged in any suitable manner. For example, the patch antenna array 102 may be shaped like a circular disc and have a diameter of about 2.0 inches (about 50.8 millimeters) or less and a thickness of about 0.25 inches (about 6.35 millimeters) or less. However, these are examples only, and other packages for the patch antenna array 102 may be used.
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Each input signal 302a-302b is provided to a respective phase-tapered splitter 304a-304b. The phase-tapered splitters 304a-304b divide the input signals 302a-302b into sets of sub-signals 306a-306b, respectively. For example, each phase-tapered splitter 304a-304b may equally or unequally divide one of the input signals 302a-302b into the sub-signals 306a-306b (which may have equal or unequal power). Each phase-tapered splitter 304a-304b can also adjust the phases of the sub-signals 306a-306b so that the resulting beams 106a-106b produced by the patch antenna array 102 are transmitted in desired directions. This can be accomplished in various ways, such as by designing the phase-tapered splitters 304a-304b so that the sub-signals 306a-306b travel through conductive paths of different lengths before reaching the patch antenna elements 202. The phase taper provided by each phase-tapered splitter 304a-304b translates into the beam angle of the resulting beam 106a-106b. Thus, for instance, the beam 106a at an angle ϕ can be produced by the phase-tapered splitter 304a providing an electrical phase taper denoted a per row of patch antenna elements 202, and the beam 106b at an angle θ can be produced by the phase-tapered splitter 304b providing an electrical phase taper of 13 per row of patch antenna elements 202. The phase-tapered splitters 304a-304b may also generate circular polarizations in different directions (“right hand” versus “left handed”) for the different beams 106a-106b. Each phase-tapered splitter 304a-304b includes any suitable structure configured to split an input signal and adjust phases of the resulting sub-signals.
One of the sub-signals 306a can be provided to each patch antenna element 202 of the patch antenna array 102, and one of the sub-signals 306b can be provided to each patch antenna element 202 of the patch antenna array 102. Prior to reaching the patch antenna element 202, each pair of one sub-signal 306a and one sub-signal 306b is provided to a 90° hybrid transformer 308. Depending on which input signal 302a or 302b is being received, the 90° hybrid transformer 308 allows one of the sub-signals 306a or 306b to be provided to the associated patch antenna element 202 of the patch antenna array 102. The 90° hybrid transformer 308 also splits the received sub-signal 306a or 306b (typically equally), provides one portion of the received sub-signal 306a or 306b to one input of the patch antenna element 202, and provides another portion of the received sub-signal 306a or 306b to another input of the patch antenna element 202. The two portions of the sub-signal 306a or 306b are out-of-phase, namely one portion of the sub-signal 306a or 306b is 90° out-of-phase with the other portion of the sub-signal 306a or 306b. Overall, the 90° hybrid transformer 308 provides isolation between the two sub-signals 306a, 306b and ensures that one sub-signal does not affect the other. Each 90° hybrid transformer 308 includes any suitable structure configured to isolate sub-signals and ensure that the sub-signals are out-of-phase.
Note that the components illustrated in a dashed box 310 can be replicated multiple times, such as once for each antenna element 202 in a quadrant 206a-206d or other portion of the patch antenna array 102. All of these antenna elements 202 may be fed by outputs of the same phase-tapered splitters 304a-304b. A dashed box 312 in
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Note that there are eight I/O connectors 404a-404h in this example, which may be used to provide two input signals 302a-302b to each of four quadrants 206a-206d of the patch antenna array 102. For instance, the I/O connectors 404a-404d may be used to provide the same input signal 302a to the four quadrants 206a-206d of the patch antenna array 102, and the I/O connectors 404e-404h may be used to provide the same input signal 302b to the four quadrants 206a-206d of the patch antenna array 102. However, the layer 400 of the patch antenna array 102 can support any suitable number of inputs/outputs in any suitable arrangement.
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Each electrical trace 414 and 424 represents any suitable pathway configured to transport an electrical sub-signal. Each electrical trace 414 and 424 can be formed from any suitable conductive material(s), such as one or more metals, and in any suitable manner, such as deposition and etching. Each electrical trace 414 and 424 includes multiple connection points 416 and 426, which represent areas where the electrical traces 414 and 424 can be coupled to other layers of the patch antenna array 102 using the conductive stubs or vias.
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While not shown here, one or more additional layers would typically be used in the patch antenna array 102. For example, one or more intermediate layers of dielectric material(s), routing electrical pathways, or other components of the patch antenna array 102 may be positioned between the layers 400 and 410, between the layers 410 and 420, between the layers 420 and 430, and/or between the layers 430 and 440. The conductive stubs or vias connecting adjacent ones of the layers 400, 410, 420, 430, and 440 can pass through the dielectric material(s) forming the intermediate layers. Also, one or more protective layer or other layers may coat the exposed surfaces of the top and bottoms layers 440 and 410. In addition, any of the electrical pathways in any of the layers (or intermediate layers) may include tuning stubs, which represent conductive portions of electrical pathways that can be modified (such as trimmed) to adjust the electrical pathways (from the perspective of the electrical signals being transported) as needed to achieve impedance matching between RF transitions.
In addition, note that the design of the patch antenna array 102 enables its fabrication in various ways, including the use of standard PCB processing techniques. Thus, for example, each layer 400, 410, 420, 430, and 440 may be formed by obtaining a suitable printed circuit board and depositing metal(s) or other material(s) on the printed circuit board, etching the metal(s) or other material(s) as needed, and/or attaching components to the printed circuit board. Of course, the patch antenna array 102 may be fabricated in any other suitable manner, and this disclosure is not limited to any particular fabrication technique.
All of the various layers 400, 410, 420, 430, and 440 here include one or more notches 450. In this example, the patch antenna array 102 includes one notch 450 in a specified position. As with the projection 206, the notch or notches 450 may be used to help ensure that the patch antenna array 102 is installed with a correct orientation in a larger device or system, which may help to avoid installing the patch antenna array 102 in an improper orientation that causes the beams 106a-106b to radiate in undesired directions.
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It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.
The description in the present application should not be read as implying that any particular element, step, or function is an essential or critical element that must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of the claims invokes 35 U.S.C. § 112(f) with respect to any of the appended claims or claim elements unless the exact words “means for” or “step for” are explicitly used in the particular claim, followed by a participle phrase identifying a function. Use of terms such as (but not limited to) “mechanism,” “module,” “device,” “unit,” “component,” “element,” “member,” “apparatus,” “machine,” “system,” “processor,” or “controller” within a claim is understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and is not intended to invoke 35 U.S.C. § 112(f).
While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.
