Antenna array having antenna elements with integrated filters

Abstract

A phased array antenna includes a plurality of antenna elements, each of which is an antenna assembly comprising an antenna integrated with a filter. Each antenna assembly includes a plurality of resonators, at least some of which are enclosed in a metal cavity and at least one resonator exposed to free space to form a radiator element. Each antenna assembly has a filter transfer function determined at least in part by the size of the radiator element and its position within the antenna assembly. The scan volume of the phased array antenna is determined by at least one physical dimension of the filter of the antenna assembly.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Provisional Application No. 62 / 793,772, filed on January 17, 2019, entitled “Multi-patch Antenna Having An Intrinsic Filtering Behavior,” with Docket No. KII-SC PRO 00011 US, and Provisional Application No. 62 / 884,855, filed on August 9, 2019, entitled “5G Phased Array Antenna Modules,” with Docket No. KII-SCPRO 00013 US, both of which are assigned to the present assignee and are hereby expressly incorporated by reference in their entirety.

[0003] This application is related to PCT patent application entitled “ANTENNA APPARATUS WITH INTEGRATED FILTER”, attorney docket number KII-SC 00011 A US, and PCT patent application entitled “ANTENNA APPARATUS WITH INTEGRATED FILTERHAVING STACKED PLANAR RESONATORS”, attorney docket number KII-SC 00011 B US, both of which were filed concurrently with the present application, assigned to the present assignee, and are hereby expressly incorporated herein by reference. Technical Field

[0004] The present invention relates generally to wireless communications and, more particularly, to phased array antennas. Background Art

[0005] In wireless communication systems, antennas are used to receive and / or transmit electromagnetic signals. During transmission, they emit electrical energy, while during reception, they capture it. In radio frequency (RF) systems, filters are placed behind the antenna to suppress any interference outside the system's frequency band of interest. Filters are typically designed as interconnected resonators that are appropriately coupled to operate in the desired frequency band while providing sufficient selectivity. The resonant frequency of this structure is directly related to the physical size and overall structure of the resonators. Typically, resonance is achieved when the resonator's physical size approaches half a wavelength. Phased array antennas have multiple antenna elements, and the input signals to these elements can be manipulated to control the direction of the antenna beam. Scan volume is a characteristic of phased array antennas, based on the maximum angle the beam can be directed from the boresight while maintaining a specified active return loss level. In other words, the scan volume is the volume of space in front of the array into which the beam can be directed while maintaining a specified active return loss level. The scan volume can be increased by reducing the grid spacing between antenna elements. Summary of the Invention

[0006] A phased array antenna includes a plurality of antenna elements, each of which is an antenna assembly comprising an antenna integrated with a filter. Each antenna assembly includes a plurality of resonators, at least some of which are enclosed in a metal cavity and at least one resonator is exposed to free space to form a radiator element. Each antenna assembly has a filter transfer function determined at least in part by the size of the radiator element and its position within the antenna assembly. The scan volume of the phased array antenna depends on at least one physical dimension of the filter of the antenna assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A is a block diagram of a phased array antenna including a plurality of antenna elements, where each antenna element includes an antenna arrangement with an integrated filter.

[0008] Figure 1B yes Figure 1A A block diagram of an example of one of multiple antenna elements within a phased array antenna.

[0009] Figure 1C is a block diagram of an antenna device with an integrated filter.

[0010] Figure 2A is an illustration of an exploded perspective view of an example of an antenna device including planar resonator elements between ground planes, wherein the ground planes are connected to vias and wherein openings in the ground planes provide coupling between the resonator elements.

[0011] Figure 2B The antenna device is along Figure 2A Illustration of a cross-sectional side view of AA.

[0012] Figure 2C is a diagram showing a perspective view of an antenna device whose housing is transparent.

[0013] Figure 3A is a perspective view illustration of an antenna arrangement showing modeling tags for an example of coupling matrix modeling.

[0014] Figure 3B yes Figure 3A Illustration of the coupling matrix modeling relationship of the structure.

[0015] Figure 4A is an illustration of an exploded perspective view of an example of an antenna arrangement with dual linear polarization.

[0016] Figure 4B It is along Figure 4A A cross-sectional top view of the antenna device taken along line BB in FIG.

[0017] Figure 5 is an illustration of an exploded perspective view of an example of an antenna arrangement with dual polarization and a resonant cavity that generates transmission zeros in the transfer function for both polarizations.

[0018] Figure 6A is an exploded perspective illustration of an example of an antenna arrangement with circular polarization.

[0019] Figure 6B is a perspective view illustration of an antenna arrangement showing modeling tags for an example of coupling matrix modeling.

[0020] Figure 6C yes Figure 6B Illustration of the coupling matrix modeling relationship of the structure.

[0021] Figure 7 is an illustration of a cross-sectional side view of an example of an antenna device including planar resonator elements between ground planes, wherein the ground planes are connected to vias and wherein coupling between the resonator elements is provided by the vias of the ground planes.

[0022] Figure 8A is an illustration of an exploded perspective view of an example of an antenna device including planar resonator elements between ground planes, wherein the ground planes are connected to vias and wherein non-adjacent resonator elements are coupled by dumbbell couplers.

[0023] Figure 8B is an illustration of a cross-sectional side view of an antenna device.

[0024] Figure 9 is an illustration of a cross-sectional side view of an example of an antenna arrangement with non-adjacent cross-coupling achieved by vias and metal strips.

[0025] Figure 10A is an illustration of a perspective view of an example of a phased array antenna and an associated scan volume antenna pattern.

[0026] Figure 10B is an illustration of a top view of an example of a phased array antenna and an associated scan volume antenna pattern.

[0027] Figure 10C is an illustration of a top view of a portion of a phased array antenna.

[0028] Figure 10D is an illustration of a front view of a portion of a phased array antenna.

[0029] Figure 10E is an illustration of a side view of a portion of phased array antenna 1000 . DETAILED DESCRIPTION

[0030] As mentioned above, filters are connected to antennas in RF systems to suppress interference outside the frequency band of interest. Because antennas often fail to provide the required selectivity, antennas and filters are designed separately and then interconnected to achieve the desired functionality. Filters are typically designed as interconnects of resonators that are appropriately coupled to operate in the desired frequency band while providing sufficient selectivity and proper passband impedance matching. Phased array antennas include multiple antenna elements, each of which is connected to a filter. In conventional systems, the grid spacing of the antenna elements often prevents each filter from being located adjacent to its corresponding antenna element. Consequently, the connections between the filter and antenna element may include wires, microstrip lines, striplines, conductive traces, or other conductive connections that introduce signal loss. Furthermore, in conventional systems, the filter and antenna elements are often implemented separately, requiring an impedance matching network to be inserted between the filter and antenna element. This can result in additional losses and a reduction in scanning volume. In a phased array, the active impedance seen by the antenna changes with scanning angle, so the impedance matching network must provide a compromise between the different active impedances seen by the antenna to achieve a certain level of return loss at all angles within the scanning volume.

[0031] According to the examples discussed herein, each antenna element of a phased array antenna includes an antenna device that is a radiating structure with the same inherent behavior as a filter. Consequently, the filter is part of each antenna element, and the phased array antenna provides filtering. Each integrated filter antenna device forming an antenna element can be implemented to accommodate a grid spacing much smaller than those possible with conventional techniques for implementing filters within the grid spacing. As a result, lossy connections between the radiator and the filter are eliminated, while the scan volume is increased with a smaller grid spacing compared to conventional antennas.

[0032] Filter design methods are applied to create a radiating structure (antenna) with the same inherent behavior as a filter, resulting in an antenna device that forms an antenna element. For example, it transmits and receives signals within a limited passband while suppressing (or at least significantly attenuating) signals outside the passband. As a result, two functions (radiation and filtering) are combined in a single structure. While conventional antennas may have inherent filtering characteristics with some frequencies attenuated, the example antenna device discussed herein is designed to achieve a specific desired filter transfer function by selecting the dimensions of the resonator, radiator, and overall structure, as well as the dimensions related to the relationship between the radiator and the rest of the structure. Thus, the structure is configured to achieve a desired overall frequency response by considering the interaction between the radiator and other components, including the filter. Furthermore, interconnects can be eliminated, reducing ohmic losses and resulting in a compact structure. A compact structure is beneficial in many cases for both standalone single-antenna systems and multi-element antenna arrays. As described above, the antenna device's compact structure allows it to be implemented as each antenna element within a phased array antenna, with a grid spacing of half a wavelength or less. Thus, the phased array antenna includes filtering functionality. The resulting phased array structure with integrated filtering has a design characteristic in which the filter design parameters determine, among other performance characteristics, the scan volume. Because the size of the radiating element of each antenna element is at least partially limited by the component size of the antenna arrangement's resonators, the choice of resonator size limits the size of the phased array antenna's grid spacing. The scan volume is at least partially determined by the grid spacing and, therefore, depends on at least one dimension of one of the resonators in the antenna arrangement.

[0033] In some examples discussed below, antenna devices include multiple metal patch resonators enclosed within a metal cavity, stacked vertically, and coupled to each other. Using one technique, coupling between the metal patches is achieved through precisely shaped openings, or irises, in the ground plane. In other cases, interlayer electrical connections using metal posts (sometimes called vias) are used to couple the metal patches.

[0034] One advantage of the structure discussed is the use of one of the resonators (the radiating resonator) as a radiator. The radiating resonator is not completely enclosed, allowing the structure to radiate into free space and act as an antenna. Through dimensional control in all three spatial dimensions and coupling to free space and the underlying resonator, a filter is formed that radiates into free space. Consequently, the filter transfer function of the antenna arrangement is at least partially based on the distance between the radiator element (the resonator element exposed to free space) and another component of the antenna arrangement (e.g., a ground patch between the radiator element and another resonator metal patch).

[0035] Figure 1AFIG1 is a block diagram of a phased array antenna 10 including multiple antenna elements 12, each of which includes an antenna assembly 14 with an integrated filter. For example, multiple antenna elements 12 are secured within a frame or other component (not shown) such that antenna elements 12 remain fixed in position relative to the other antenna elements. In some cases, the entire phased array structure can be moved and oriented as a single unit. In a typical implementation, each antenna element is connected to other circuitry so that the phase of the transmit and / or receive signals can be manipulated to change the direction and / or shape of the antenna beam formed by the phased array antenna.

[0036] The antenna elements are separated from each other by a grid spacing, where the size of the antenna elements 12 generally determines the grid spacing. Because the antenna elements are not necessarily square, the grid spacing 16 in a first dimension (e.g., width) 18 of the phased array grid can be different from the grid spacing 20 in a second dimension (e.g., length) 22. A phased array antenna can include any number of antenna elements. Figure 1A In the example shown, a four-by-four array is shown with black dots to indicate that additional antenna elements can be included in both dimensions 18 and 22. The array can include any number of elements, with typical numbers ranging from 16 to several thousand. The number of antenna elements in each orientation and the grid spacing typically depend on the specific application of the antenna array. For base stations operating according to the 5G specification, the antenna array typically has 64 elements arranged in an 8-by-8 configuration. Multiple antennas can also be operated together to form larger arrays, such as 128, 256, 512, 1024 elements, or other configurations. For indoor applications and mobile devices, the array size is smaller, typically having 16 elements in a 4x4 or 2x8 array configuration. In some cases, the scan volume in the horizontal dimension is larger than the scan volume in the vertical dimension, with an example of a suitable grid spacing in terms of wavelength (λ) being approximately 0.45λ by 0.65λ.

[0037] For the examples herein, the grid spacing is uniform along the dimensions, such that the spacing 16 along the first dimension 18 is the same and the spacing 20 along the second dimension 22 is the same, although the first dimension spacing 16 may be different than the second dimension spacing 20. However, in some cases, the grid spacing along at least one of the dimensions 18, 22 may be non-uniform.

[0038] Figure 1B yes Figure 1A FIG1 is a block diagram of an example of one of multiple antenna elements 12 within a phased array antenna 10. Each of the antenna elements 12 in the examples herein is an antenna assembly 14 that is an integrated structure including at least two resonators 24, 26 coupled to each other, one of the resonators being a radiating element 24. At least one other resonator 26 is enclosed within a metal housing 28.

[0039] Figure 1C is a block diagram of an antenna device 100 with an integrated filter. The antenna device 100 is a radiating filter in which at least two resonators are coupled to each other and one of the resonators is a radiator. Depending on the specific implementation, the antenna device can be used for transmission, reception, or both. Thus, the antenna device 100 is Figure 1A and Figure 1B An example of the antenna device 14. Figure 1C In the example of , the antenna device 100 includes an input resonator 102, an intermediate resonator 104, and an output resonator 106 forming a radiator. As described below, the antenna device 100 may include several intermediate resonators 104. For the examples herein, each non-radiating resonator 102, 104 is formed with a metal resonator element 108, 110, which is located within a cavity 112, 114 of a metal housing 116, 118. The metal housing 116, 118 forms an electromagnetic housing at the operating frequency and therefore may not include a continuous metal wall without any openings. As described below, for example, a series of metal posts (vias) between two planar conductive patches can form the side walls of the metal housing, where the two planar conductive patches form the top and bottom of the metal housing. In another example, a metal screen can be used to form the metal housing. In each cavity of the example, a dielectric ( Figure 1C (not shown). A portion of one metal housing may form a portion of another metal housing. For example, where the resonators are implemented using planar conductive patches positioned between ground plane layers, the ground plane layer between two adjacent resonators may form the top of the lower metal housing and the bottom of the upper metal housing.

[0040] The resonator elements are coupled to each other via couplings 120, 122. Each coupling 120, 122 can be formed using a conductive element such as a post or screw, or can be implemented using an opening in the ground plane that separates the resonator elements. As discussed below, for example, a coupling can be formed using an iris in the ground plane that separates two adjacent resonator elements. Couplings 120, 122 can also be formed between non-adjacent resonator elements. Thus, couplings 120, 122 can be any mechanism that couples electromagnetic energy between any two resonator elements.

[0041] Input resonator 102 has an input port 124 that can be connected to a signal source or receiver. Thus, input port 124 provides an interface to other devices, components, and circuits. The transfer function 126 of antenna device 100 from input port 124 through output resonator (radiator) 106 is determined by at least the properties of the non-radiating resonators 102, 104, couplings 120, 122, and radiating resonator 106, as well as the position of the radiator relative to the other components. In most cases, transfer function 126 also depends on the characteristics of input port 124. Therefore, by selecting the dimensions of resonators 102, 104, 106 and couplings 120, 122, and the relative position of radiator 106 within the structure, transfer function 126 can be adapted or configured to meet specific criteria. For example, in an implementation where the resonators are stacked resonator elements within a groundplane housing and the coupling is formed using an iris in the groundplane, the transfer function depends on at least the shape and size of the iris, the distance between the resonator elements, the dimensions of the resonators, the distance between the last resonator (radiator) and the adjacent groundplane, and the size of the input strip. Therefore, the design of the antenna device takes into account the properties of the output resonator and its interaction with other components within the antenna device structure. Consequently, the spacing (distance) between the radiator 106 and the adjacent ground plane (lower in the figure), in addition to other design parameters, is selected to achieve the desired overall filter transfer function. Therefore, the distance (D1) 128 between the radiator 106 and the adjacent resonator element 110, as well as the distance (D2) 130 between the radiator 106 and the ground plane of the housing, are selected to provide the desired output coupling and transfer function. For the examples herein, the output coupling is adjusted by adjusting D1 128 and D2 130. Furthermore, if D1 128 is changed without changing D2 130, the selectivity is altered without changing the output coupling. Therefore, the filter transfer function is generally adjusted by adjusting the distances D1 128 and D2 130.

[0042] Consequently, the spacing (distance) between the radiator 106 and the adjacent resonator element 110 is selected, in addition to other design parameters, to achieve the desired overall filter transfer function 126. More specifically, the distance (D1) 128 between the radiator 106 and the adjacent resonator element 110 influences the selectivity 129 of the filter response of the filter transfer function 126, and the distance (D2) 130 between the radiator 106 and the adjacent ground plane 132 influences the free-space output coupling. In the example, the size of the iris 122 influences the selectivity, similar to the change in D1. For the example discussed herein, the adjacent ground plane 132 is formed using a portion of the housing 118 adjacent to the output resonator element 106. As discussed herein, the selectivity 129 of the filter transfer function 126 is the shape of the filter response that decays with frequency. Therefore, selectivity 129 includes parameters such as the bandwidth of the passband and stopband, as well as the transition characteristics between the passband and stopband. Thus, at least the distance (D1) 128 between the radiator 106 and the adjacent resonator element 110 and the distance (D2) 130 between the radiator 106 and the ground plane of the housing are selected to provide the desired output coupling and filter response. As described below, the filter transfer function is also based on the dimensions of the resonator elements 106, 108, 110 and the dimensions of the structure that forms the coupling between the resonators.

[0043] For the discussion herein, reciprocity exists between the antenna device as a transmitting device and as a receiving device. Therefore, the receiving and transmitting properties of the antenna device are the same for the example. The characteristics, design parameters, and configuration of the antenna device discussed with reference to transmission can be applied to the antenna device when used as a receiving device. Therefore, when the antenna device is used to receive a signal, the radiator captures the signal and provides an output at the input port. More specifically, because the antenna device 100 is a linear passive structure, the reciprocity theorem applies to its operation as a transmitter and receiver. Therefore, the antenna device 100 behaves exactly the same in transmission and reception. In the transmission mode, the signal at the input port 124 of the antenna device 100 induces a current in the radiator 106, resulting in the transmission of an electromagnetic field into free space. In the receiving mode, the electromagnetic wave in free space that reaches the antenna device 100 induces a current in the radiator 106, which in turn generates a signal at the input port 124 of the antenna.

[0044] Figure 2A is an illustration of an exploded perspective view of an example of an antenna device 200 that includes planar resonator elements between ground planes, where the ground planes are connected to vias and where openings in the ground planes provide coupling between the resonator elements. Figure 2B The antenna device 200 is along Figure 2A Illustration of a cross-sectional side view of AA. Figure 2C 2 is a diagram showing a perspective view of the antenna device 200 in which the housing 201 is transparent. Figure 2A 、 Figure 2B and Figure 2C The drawings are not necessarily to scale and are not intended solely for general illustration of the relative positioning of components. For the examples discussed herein, housing 201 surrounds the antenna assembly structure, except for openings for the input port and radiator. In addition to providing additional shielding and grounding connections, housing 201 also provides structural stability. Examples of suitable techniques for forming housing 201 include using sheet metal, metal through-holes, and combinations thereof. However, in some cases, housing 201 may be omitted.

[0045] Figure 2A and Figure 2B The antenna device 200 of the example of FIG. 2 includes an input resonator 202, two intermediate resonators 204, 206 and an output resonator (radiator) 208. Therefore, the antenna device 200 of FIG. 2 is the same as that described above with reference to FIG. Figure 1C An example of the antenna device 100 discussed. The resonator housings 210, 212, 214 for the resonators 202, 204, 206 are formed by two ground planes connected to each other by a set of through holes 216, 218, 220. With the exception of the output resonator element 222, which forms the radiator, each radiator element 224, 226, 228 is enclosed within a housing formed by the two ground planes and the set of through holes 216, 218, 220 connected between the two ground planes. Two internal ground planes 230, 232 each form a portion of the two resonator housings 210, 212. For example, the lower middle ground plane 230 forms the top of the input resonator housing 210 for the input resonator 202 and also forms the bottom of the lower middle housing 212 for the lower middle resonator 204. The upper middle ground plane 232 forms the top of the lower middle housing 212 for the lower middle resonator 204 and forms the bottom of the upper middle resonator 214 for the upper middle resonator 206. For example, the metal patch structure forming the resonator is enclosed in the housing 201, with only the radiator exposed to free space and an opening providing access to the input port. Figure 2A and Figure 2B The housing 201 is not shown.

[0046] In addition to the bottom (lower) ground plane 234, the ground planes 230, 232, 236 include openings 238, 240, 242 that provide coupling between adjacent resonator elements. In other examples discussed below, the bottom ground plane can include an opening that provides coupling to the resonant cavity below the bottom ground plane. As described above, the opening in the ground plane that provides coupling can be referred to as an iris. The size and shape of the iris dictate the characteristics of the coupling. Therefore, the filter transfer function of the antenna device can be established at least in part by selecting the shape and size of the iris. In addition, the shape orientation of the iris and the resonator determines the polarization of the antenna device's radiation pattern. As discussed below, the antenna device can be designed to have single polarization, dual polarization, or circular polarization. Therefore, the selection of the size and shape of the iris can be used to obtain a desired filter transfer function and polarization radiation pattern.

[0047] The resonator element and the ground plane are connected by a dielectric material ( Figure 2A 246). In one example, the antenna arrangement is formed using printed circuit board (PCB) technology. Thus, the ground plane and resonator elements can be formed from a metal sheet laminated onto a dielectric material substrate 246. For the examples discussed herein, a dielectric material having a dielectric constant greater than that of air is used and is partially shown as hatched in some of the figures. For clarity, the figures with exploded views do not show the dielectric. For the examples, the dielectric material is uniform within the structure, although in some cases different dielectric materials may be used. A plurality of through-holes between a pair of ground planes form the side walls of each resonator housing. The input port is formed using a portion of a stripline 247 extending through the lower housing. Other techniques may be used to form the input.

[0048] In another example, the input port is formed by a metal post or through-hole extending through the lower housing. When the antenna device 200 is used to transmit a signal, a transmitter is connected to the input port and a radio frequency (RF) signal is fed to the antenna device through the input port. The RF signal is filtered by the antenna device, and the filtered signal is radiated from the radiating element. The size of the resonant element determines the resonant frequency of the resonator. Figure 2A and Figure 2B In this example, each resonant element is a rectangular metal patch, and the resonator elements are slightly different in size. Although the resonators are of similar size, the different loading of each resonator results in different sizes. The size of the rectangular metal patch that determines the resonance of the resonator is the distance from the input side to the opposite side. Therefore, for Figure 2A, the distances 250, 252, 254, 256 determine the resonant frequency of the resonator. The desired filter response is achieved by selecting the dielectric, the length of the metal patch, the length of the iris, the spacing between the ground plane and the resonator elements, the spacing between adjacent resonator elements, and the spacing D2 130 between the last resonator (radiator) 106 and the adjacent ground plane 132, which is the ground directly below the radiator in the figure. As discussed above, the distance (D1) 128 between the radiator 106 and the adjacent resonator element 110 affects the selectivity 129 of the filter response of the filter transfer function 126, and the distance (D2) 130 between the radiator 106 and the adjacent ground plane 132 affects the output coupling to free space. Therefore, for Figure 2A and Figure 2B In the example of FIG. 2 , the distance 248 between the metal patch forming the radiator 222 and the metal patch forming the upper intermediate resonator element 228 partially determines the selectivity of the filter response. The output coupling to free space depends at least in part on the distance 258 between the metal patch radiator 222 and the ground plane 236. Thus, the distance 248 between the metal patch radiator 222 and the metal patch resonator element 228 is Figure 1C An example of a distance (D1) 128 between the radiator 106 and the adjacent resonator element 110. The distance 258 between the metal patch radiator 222 and the ground plane 236 is Figure 1C 1. An example of a distance (D2) 130 between the radiator 106 and the ground plane 132.

[0049] By selecting the dimensions of the resonators 202, 204, 206, 208, the characteristics of the structures forming couplings between the resonators, and the spacing between the components of the resonators, as well as the dimensions of the radiator 222, the characteristics of the structures forming couplings to the radiator 222, and the relative position of the radiator 222 to the other components of the antenna device 200, the antenna device 200 is constructed to have a desired filter transfer function 126 from the input stripline 247 to free space.

[0050] As discussed in further detail below, one of the advantages of the antenna device includes the ability to implement the filter and antenna in a package that is less than half a wavelength (λ / 2) on either side of the radiating plane. While the antenna device can be implemented in areas of different shapes and larger sizes, in some cases it is advantageous to limit the size to less than half a wavelength (λ / 2) on either side. Figure 2CIn the example of FIG, the plane of housing 201 in which the radiator is located has a width 248 and a length 250 that are less than half a wavelength (λ / 2). In other cases, multiple antenna devices are provided in a single housing, with each radiator in the single housing being within an area less than λ / 2 on each side. In still other cases, the dimensions of housing 201 are such that the device fits within a grid spacing that is less than λ / 2 in only one orientation of the array.

[0051] Figure 3A is a perspective view illustration of the antenna arrangement 200 showing an example modeling tag for coupling matrix modeling. Figure 3B yes Figure 3A A diagram of the coupling matrix modeling relationship of a structure of . One technique for simulating filter circuits and designing filters includes a coupling matrix model, which is an example of a technique that can be applied to design antenna devices according to the discussion herein.

[0052] At microwave and millimeter-wave frequencies, bandpass filters are typically constructed from interconnected (i.e., coupled) resonators. Resonators can be coupled in cascade (i.e., between adjacent resonators), resulting in an all-pole frequency response, or can include coupling between non-adjacent resonators, leading to a more complex frequency response that can include transmission zeros. These filters can be modeled using simple lumped-element circuits. For a general two-port model of a synchronous direct-coupled resonator filter, both direct coupling (between adjacent resonators) and cross coupling (between non-adjacent resonators) can be represented. Circuit simulators can be used to simulate the circuit response, including all possible couplings (adjacent and non-adjacent), and can include synchronous resonators (formed by capacitors and inductors), admittance inverters, and frequency-independent admittance. Examples of suitable circuit simulators include N1 AWR MicrowaveOffice and Ansys Designer circuit simulators. Once the filter's center frequency and bandwidth are defined, the filter circuit can be represented in matrix form, known as the coupling matrix. The entries of the coupling matrix M represent the different components of the circuit. The diagonal elements represent the imaginary part of the frequency-independent admittance, while the off-diagonal entries represent the coupling between the resonators (i.e., the inversion constant). This modeling and design method is used to simulate and design a bandpass direct-coupled resonator filter and is one example of a technique that can be used to design the examples of antenna devices discussed herein. Figure 3A An example of a cascade connection where resonators are coupled in a cascade connection, where adjacent resonators couple to form a full-pole frequency response. This model can also be applied to coupling to a radiator and from the radiator to free space.

[0053] According to one example, the center frequency, bandwidth, passband, ripple return loss level, and transmission zero location of the filter are selected. Using these parameters, the coupling matrix that synthesizes the response can be analytically calculated.

[0054] The coupling matrix is converted into a practical implementation by identifying the physical geometric features that govern the individual elements of the coupling matrix. Typically, for example, the size of a resonator can be varied to change its resonant frequency (i.e., the corresponding diagonal elements of the coupling matrix), and the size of the openings created between the resonators can control the amount of coupling between them. Various methods can be used to extract geometric values from the circuit pattern, with the design process typically beginning with obtaining a set of initial dimensions. This process can include examining the input group delay or breaking the structure into simpler blocks and comparing EM simulations with circuit simulations of equivalent blocks. After establishing these initial dimensions, an optimization design process is applied. Therefore, the design of an antenna device involves synthesizing a coupling matrix that provides the desired passband response and out-of-band rejection. To synthesize this coupling matrix, the number of resonators (N), center frequency (fO), bandwidth (BW), and desired passband and ripple return loss values are determined to meet certain rejection characteristics.

[0055] for Figure 3A and 3B In the example of , nine geometric dimensions are manipulated to achieve the desired filter response, where the geometric dimensions include the lengths of the four metal patches that form the resonator elements, the widths of the three openings that form the coupling between the metal patches, the distance from the metal patch radiator to the ground plane, and the width of the input tap. Figure 3B The coupling model pairs each geometric dimension with an entry in the coupling matrix. The input tap width 302 of input stripline 247 controls MS1. The length 304 of input resonator element 224 controls M11. The length 306 of the metal patch forming first intermediate resonator element 226 controls M22. The length 308 of the metal patch forming second intermediate resonator element 228 controls M33. The length 310 of the metal patch forming radiator element 222 controls M44. The length 312 of opening 238 controls M12. The length 314 of opening 240 controls M23. The length 316 of opening 242 controls M34. The distance 250 between metal patch radiator 222 and ground plane 236 controls M4L. By adjusting and optimizing the coupling matrix elements, including matrix elements corresponding to the radiator characteristics, the desired transfer function of the integrated antenna device including the filter and antenna can be achieved.

[0056] The techniques discussed above can be applied to other implementations of the antenna device 100. As discussed below, other examples of the antenna device 100 include implementations with dual polarization and multiple ports, implementations with circular polarization, and implementations with transmission zeros in the frequency response. These examples and other implementations can be simulated and optimized by appropriately modifying and applying the design techniques discussed above for specific structures.

[0057] Figure 4A is an illustration of an exploded perspective view of an example of an antenna apparatus 400 with dual polarization. Figure 4B It is along Figure 4A BB in FIG. 4 is a cross-sectional top view of the antenna device 400. Therefore, Figure 4A and Figure 4B The antenna device 400 is the above reference Figure 1C Another example of the antenna device 100 discussed. Figure 4A and Figure 4B In the example of FIG. 4 , an antenna device 400 has two input ports 402 and 404, including a horizontally polarized input port 402 and a vertically polarized input port 404. Dual directionality is achieved by adjusting the size of the same set of resonators and radiators and adjusting the shape of the iris. Each iris 406, 408, 410 is a combination of two rectangular irises 412 and 414, wherein the iris having the longer dimension perpendicular to the direction of the input port couples the signal from that input. The coupling from the irises (whose longest dimension is parallel to the direction of the input port) is significantly less, thereby providing isolation between the two input ports and the signals. Therefore, the first rectangular portion 412 of the iris having a direction perpendicular to the direction 418 of the horizontal input port 402 couples the signal received at the horizontal input port 402. The second rectangular portion 414 of the iris having a length 420 perpendicular to the direction 422 of the vertical input port 404 couples the signal received at the vertical input port 404. Each set of rectangular portions, resonators, and radiators having the same orientation functions as in reference Figure 2A 、 Figure 2B 、 Figure 3A and Figure 3B As stated.

[0058] Figure 5 is an illustration of an exploded perspective view of an example of an antenna arrangement with dual polarization and a resonant cavity (auxiliary resonator) 502 that generates a transmission zero in the transfer function for both polarizations. Figure 5In the example of FIG. 5 , a resonant cavity (auxiliary resonator) 502 is formed with a metal resonant patch 504 surrounded by an input resonator ground plane 506, another ground plane 508, and a via 510 connected to both ground planes 506 and 508. The auxiliary resonator is located on the opposite side of the input resonator 512 from the other resonators. The metal resonant patch 504 is coupled to the input resonator resonant element 514 via an iris 516 in the input resonator ground plane 506. For example, the iris 516 has the same shape and orientation as the other irises. From one perspective, the additional resonant cavity 502 provides a mechanism for canceling energy transfer at and near specific frequencies. The metal resonant patch 504 in the resonant cavity 502 is singly coupled to the input resonator. This is different from other resonators that are at least doubly coupled to the input and output of other resonators or structures. As a result, energy at the resonant frequency of the patch 504 is contained within the resonant cavity 502 and cannot continue toward the radiator to radiate into free space. This is similar to the performance of an extracted-pole filter, where single coupled resonators are located at different stages of the filter to create transmission zeros in the frequency response.

[0059] Figure 6A is an exploded perspective view illustration of an example of an antenna device 600 with circular polarization. Figure 6A The antenna device 600 is the above reference Figure 1C The example of antenna device 100 discussed above, wherein the intermediate cavity and the input cavity are a single cavity. Thus, antenna device 600 includes an input element that supports two resonances within the passband of the antenna and a radiator that also supports two resonances within the passband of the antenna device. Thus, for Figure 6A , the antenna device includes a single cavity 602 and a radiator 604. The resonator element 606 and the radiator element 604 both have notches in diagonally opposite corners to provide coupling between the two resonators contained in each patch. The notched corners 608, 610 of the radiator element 604 are located above the non-notched corners 612, 614 of the resonator element 606. Thus, the two notched corners 616, 618 of the resonator element 606 are located directly below the non-notched corners 620, 622 of the radiator element 604. Figure 6A For example, the iris 624 has an orientation with the longer dimension parallel to the direction of the input port 626. Circular polarization can be achieved by feeding two orthogonal linear polarizations with a 90 degree phase difference. This can be achieved with Figure 6AThe structure shown is implemented in such a way that the radiating patch maintains two linear polarizations. The recesses in the corners provide coupling between the two resonances maintained by each patch. A 90-degree phase difference between polarizations and input matching in the desired passband is achieved by appropriately selecting the size and position of the input pad, the size of the two patches, the size of the recesses, the size of the iris, and the relative position of the recesses between the two patches. This configuration allows for a circularly polarized antenna with a matching bandwidth equal to the axial ratio bandwidth.

[0060] Figure 6B is a perspective view illustration of an antenna arrangement 600 showing an example modeling tag for coupling matrix modeling. Figure 6C yes Figure 6B 6 is an illustration of the coupling matrix modeling relationship for a structure. As discussed above, the coupling matrix model is an example of a technique that can be applied to design antenna devices according to the discussion herein. For example, MS1 is based at least in part on the width 650 of input port 626. MS1 can also be controlled by the length 651 of the input port "steps." In this example design technique, width 650 is increased until maximum input coupling is achieved. Length 651 is then increased until the desired input coupling is achieved.

[0061] M11 and M22 are based on the length 652 and width 654, respectively, of the resonator element 606. M23 and M14 are based on the length 656 and width 658, respectively, of the iris 624. M44 and M33 are based on the length 660 and width 662, respectively, of the radiator element 604. M12 is based on the size 664 of the notched corners 616 and 622 of the resonator element 606. M34 is based on the size 666 of the notched corners 608 and 610 of the radiator element 604. M4V is based on the distance 668 between the radiator element and the adjacent ground.

[0062] Figure 7 is an illustration of a cross-sectional side view of an example of an antenna device 700 including planar resonator elements between ground planes, wherein the ground planes are connected to vias and wherein coupling between the resonator elements is provided by the vias of the ground planes. Figure 7The structure and operation of antenna device 700 are similar to antenna device 200 discussed above, except that coupling is achieved using vias 702, 704, and 706 rather than an iris. Input resonator element 224 is coupled to first intermediate resonator element 226 via a metal post or via 702 that extends through an opening 708 in ground plane 230 between resonator elements 224 and 226. First intermediate resonator element 226 is coupled to second intermediate resonator element 228 via a metal post or via 704 that extends through an opening 710 in ground plane 232 between resonator elements 226 and 228. Second intermediate resonator element 228 is coupled to radiator element 222 via a metal post or via 706 that extends through an opening 712 in ground plane 236 between resonator element 228 and radiator element 222. The modeling and design techniques discussed above can be used with antenna device 700, where the vias are represented by appropriate coupling characteristics. for Figure 7 In the example, the position and size of the through-holes control the coupling between adjacent resonators.

[0063] Figure 8A is an illustration of an exploded perspective view of an example of an antenna device 800 that includes planar resonator elements between ground planes, where the ground planes are connected with vias and where non-adjacent resonator elements are coupled by dumbbell couplers. Figure 8B FIG8 is an illustration of a cross-sectional side view of antenna device 800. The structure and operation of antenna device 800 are similar to antenna device 400 discussed above, except that a dumbbell coupler 802 couples input resonator element 804 to second intermediate resonator element 806. Dumbbell coupler 802 can be formed using a metal post or via 808 connected between patches 810 and 812. For the example of FIG8 , via 808 passes through iris 814 in ground plane 816, through opening 818 in first resonator element 820, and through iris 822 in ground plane 824. Thus, the non-adjacent coupling due to the dumbbell coupler is complementary to the coupling through the iris. Non-adjacent coupling allows for the creation of transmission zeros in the transfer function, providing greater flexibility in designing the antenna device.

[0064] Figure 9 is an illustration of a cross-sectional side view of an example of an antenna device 900 having non-adjacent cross-coupling. The structure and operation of the antenna device 900 are similar to the antenna device 200 discussed above, except that striplines and vias are used to couple non-adjacent resonators. For example, the ground planes 902, 904, 906, 908 are connected to each other with a plurality of vias 910, 912, and the lower ground plane 902 is connected to the upper ground plane 908 with a plurality of vias 914. The vias 910, 912, 914 are arranged in a manner similar to the antenna device 200 discussed above. Figure 9are shown as sidewalls, although they may contain multiple rows of staggered through-holes.

[0065] For example, a stripline connects two non-adjacent metal resonator patches that form resonator elements to a via connecting the stripline, thereby coupling the two resonator elements. Stripline 916 connects input resonator metal patch resonator 918 to via 920, and stripline 922 connects second intermediate metal patch resonator 924 to via 920. As a result, input resonator metal patch resonator 918 is coupled to second intermediate metal patch resonator 924.

[0066] To further shield the via 920, the lower ground plane 902 is connected to the via 914. For example, the lower ground plane 902 is connected to the via 914 via a metal plane 926, and the upper ground plane 908 is connected to the via 914 via another metal plane 928. In addition to the coupling between non-adjacent resonator elements 918, 924, Figure 9 The exemplary structure also includes coupling between adjacent resonators as discussed above in other examples. Input resonator element 902 is coupled to first intermediate resonator element 930 via iris 932. First intermediate resonator element 930 is coupled to second intermediate resonator element 924 via iris 934. Second intermediate resonator element 924 is coupled to radiator element 936 via iris 938.

[0067] Thus, by appropriately selecting the dimensions of the coupling and patch, as well as the distance between the radiator and adjacent resonators, the antenna device can be designed to function as a directly coupled resonator filter and antenna. By implementing non-adjacent coupling using vias, dumbbell probes, or additional resonators adjacent to the input resonator and opposite the other resonators, transmission zeros can be introduced into the transfer function. The integrated structure allows for compact implementation of the filter and antenna, which is important in at least some implementations. For example, an antenna device with appropriate filter characteristics and antenna radiation pattern and polarization can be implemented in an area less than half a wavelength at the operating frequency.

[0068] Figure 10A is an illustration of a perspective view of an example of a phased array antenna 1000 and an associated scan volume for antenna 1002, and Figure 10B is an illustration of a top view of an example of a phased array antenna 1000 and an associated scan volume for antenna 1002 . Figure 10C is a top view of a portion of the phased array antenna 1000, Figure 10D is a front view of a portion of phased array antenna 1000, and Figure 10Eis a side view of a portion of a phased array antenna 1000. Scan volume 1002 represents the portion of space in which antenna 1000 can direct its radiated energy. Phased array antenna 1000 includes a plurality of antenna elements, where each antenna element is an antenna device with an integrated filter. Thus, phased array antenna 1000 is an example of phased array antenna 10 discussed above. Figure 10A and Figure 10B In an example, phased array antenna 1000 has a first grid spacing in a first orientation 1004 and a second grid spacing in a second orientation 1006, where second grid spacing 1006 is greater than first grid spacing 1004. For a selected signal strength or antenna gain, the scan angle of the phased array antenna is the maximum angle from the boresight 1007. Because the maximum scan angle is at least partially determined by the grid spacing, the scan angle (α) 1008 in the first orientation 1004 is greater than the scan angle (β) 1010 in the second orientation 1006, and the scan volume 1002 is elliptical. In an example where the grid spacing is the same in both orientations, antenna pattern 1002 may be circular.

[0069] A phased array antenna consists of several independently controllable antennas. When used together, individual antennas or elements can be connected to separate transmitters and receivers or groups of transmitters and receivers. The electromagnetic waves radiated by each individual antenna combine and superimpose, constructively interfering (adding together) to enhance the power radiated in the desired direction and destructively interfering (cancelling) to reduce the power radiated in other directions. When used for reception, the individual electromagnetic currents from the individual antenna elements combine in the receiver with the correct phase relationship to enhance the signal received from the desired direction and cancel signals from undesired directions. Phased arrays contain components for controlling the amplitude and phase of each element to achieve "phasing" control. In other words, the array is mechanically stationary, while the electromagnetic waves are electronically steered. Active electronically controlled arrays (AESAs) include active elements placed within the phased array. The phasing properties of the antenna elements and the subsequent coupling impose additional requirements on the antenna elements for active impedance control. This phasing control requirement determines the element spacing, which is typically around half a wavelength at the upper end of the operating spectrum. Phased array antennas allow for more efficient spectrum use and help meet the needs of conventional communication systems.

[0070] However, conventional techniques are limited in that they cannot achieve the desired filtering for each antenna element within the array while meeting other requirements related to parameters such as sidelobe level, active return loss, efficiency, array gain, and scan volume. However, the antenna devices and techniques described herein enable the realization of phased array antennas that meet these requirements.

[0071] One example of a suitable technique for designing a phased array antenna involves using a circuit simulator, where one or more dimensions are selected to achieve specific characteristics and other dimensions are systematically set to adjust and compensate for other characteristics. In this example of a suitable technique for designing an antenna array, the design begins with the filter specifications and the desired scan volume. Based on the scan volume, the grid spacing in azimuth and elevation, as well as the maximum distance between the radiator patches and the planar metal ground plane, is determined. Based on these values, the maximum output coupling of the filter is calculated, and based on a circuit model of this coupling, a coupling matrix is synthesized to meet the filter specifications within the constraints of the maximum output coupling value. Based on this circuit model, the dimensions of the structure are determined as described above with respect to the design of individual antenna elements (antenna devices).

[0072] Obviously, in light of these teachings, other embodiments and modifications of the present invention will readily occur to one of ordinary skill in the art. The foregoing description is intended to be illustrative and not restrictive. The present invention is limited only by the following claims, which, when read in conjunction with the above specification and accompanying drawings, include all such embodiments and modifications. The scope of the present invention, therefore, should be determined not with reference to the above description, but rather with reference to the appended claims and their full scope of equivalents.

Claims

1. A phased array antenna, comprising: A plurality of antenna elements, each antenna element comprising: radiating elements, each radiating element being a planar metal patch radiator; ground elements, adjacent to the radiating element, each ground element being a planar metal ground patch; and resonator coupled to the radiating element via the ground element, the phased array antenna having a scan angle determined at least in part by a size of the resonator, wherein Each resonator comprises a planar metal resonator patch within a metal housing, the planar metal resonator patch having a length and a width; A first grid spacing of the phased array antenna in the first dimension is limited by the length; A second grid spacing of the phased array antenna in a second dimension is limited by the width; The scan angle at a first orientation is determined at least in part by the first grid spacing; and The scan angle at the second orientation is determined at least in part by the second grid spacing, and wherein, Each planar metallic resonator patch has an input port, and each antenna element is configured to radiate electromagnetic energy from the planar metallic patch radiator when an electromagnetic signal is applied to the input port according to a transfer function from the input port through the planar metallic patch radiator to free space, The transfer function is determined at least in part by the distance between the planar metal patch radiator and the planar metal resonator patch.

2. The phased array antenna according to claim 1, wherein: The selectivity of the transfer function is based at least in part on a distance between the planar metal patch radiator and the planar metal resonator patch.

3. The phased array antenna according to claim 1, wherein: An output coupling to free space of the transfer function is based at least in part on a distance between the planar metallic patch radiator and the planar metallic ground patch.

4. The phased array antenna according to claim 1, wherein: The opening in the planar metal ground patch creates a coupler to electrically couple the planar metal resonator patch to the planar metal patch radiator.

5. The phased array antenna according to claim 1, wherein: The metal housing is formed by the planar metal ground patch and another planar metal ground connected by a set of metal pillars.

6. The phased array antenna according to claim 1, wherein: Each antenna element is configured to radiate electromagnetic energy from the radiating element according to circular polarization when an electromagnetic signal is applied to the input port.

7. The phased array antenna according to claim 1, wherein: Each planar metal resonator patch has another input port, and each antenna element is configured to: radiate electromagnetic energy from the planar metal patch radiator according to right-hand circular polarization RHCP when the electromagnetic signal is applied to the input port; and radiate electromagnetic energy from the planar metal patch radiator according to left-hand circular polarization LHCP when the electromagnetic signal is applied to the other input port.

8. The phased array antenna according to claim 1, wherein: The first grid spacing and the second grid spacing are smaller than half a wavelength of the electromagnetic signal at a frequency in free space.

Images