An X-band direction-finding antenna and antenna device

Abstract

This invention discloses an X-band direction-finding antenna and antenna device. The antenna includes an array layer, a cavity layer, and a network layer stacked sequentially from front to back. An antenna array is disposed on the array layer, and an array port is disposed on the antenna array. The array port is connected to the network layer and an output terminal disposed on the antenna through the cavity layer. The antenna device includes an antenna and an antenna support, with the antenna disposed on the antenna support. This X-band direction-finding antenna has a high degree of integration, small size, and light weight, achieving miniaturization. Simultaneously, it exhibits a low standing wave ratio and high element radiation efficiency in the X-band.

Description

Technical Field

[0001] This invention relates to antenna technology, and in particular to an X-band direction-finding antenna and antenna device. Background Technology

[0002] The rapid development of electronic communication technology has led to the existence of various electromagnetic wave signals in space, such as radar signals, mobile phone signals, and television signals. In this complex electromagnetic environment, technologies for determining the location of various electromagnetic signals have emerged; this technology is known as radio direction finding. Radio direction finding has significant research value, ranging from ensuring the safety of civilians from electromagnetic interference to safeguarding national security in electronic warfare. In fact, rapid and accurate direction finding capabilities are crucial for all military systems, including self-defense equipment, homing weapons, and real-time situational awareness tools.

[0003] Direction finding is the measurement of direction. Direction finding systems generally use multi-beam antennas, and there are generally three methods to achieve direction finding: amplitude comparison direction finding, phase comparison direction finding, and amplitude-phase comparison direction finding. Many scholars at home and abroad have studied direction finding antennas in the communication frequency band and proposed various direction finding antennas, which have improved antenna performance and solved many problems. However, problems such as large frequency variations, narrow bandwidth, large weight, and large height still exist to varying degrees.

[0004] In recent years, the research on X-band direction finding antennas has made great progress. However, in general, most existing direction finding antennas are still large in size, heavy in weight, and have a low degree of integration, which cannot meet the requirements for miniaturization. At the same time, the antennas have a large standing wave ratio in the X-band and low element radiation efficiency.

[0005] Therefore, how to improve the integration level of direction-finding antennas, achieve antenna miniaturization, and reduce antenna VSWR and improve unit radiation efficiency have become technical problems that need to be solved by those skilled in the art. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide an X-band direction-finding antenna that solves the problems of low integration, large size, heavy weight, large standing wave ratio and low unit radiation efficiency in the existing antenna technology.

[0007] Technical solution: An X-band direction-finding antenna of the present invention includes an array layer, a cavity layer and a network layer stacked sequentially from front to back. An antenna array is disposed on the array layer, and an array port is disposed on the antenna array. The array port is connected to the network layer and an output terminal disposed on the antenna through the cavity layer.

[0008] Preferably, the antenna array includes a first antenna array unit, a second antenna array unit, a third antenna array unit, and a fourth antenna array unit arranged in quadrants, and the array ports include a first array port, a second array port, a third array port, and a fourth array port, with each array port correspondingly located at the center of each antenna array unit.

[0009] Preferably, each antenna array element has an array microstrip line, which includes a horizontally arranged transverse microstrip line, a vertically arranged vertical microstrip line, and microstrip units. The transverse microstrip line is arranged on both sides of the vertical microstrip line and connected to the vertical microstrip line, and the microstrip unit is arranged on the transverse microstrip line.

[0010] Preferably, multiple coupling feed slots are formed on the coupling surface between the cavity layer and the array layer, and the positions of the coupling feed slots and the microstrip units correspond one-to-one in the front-to-back direction.

[0011] Preferably, the network layer includes a dielectric substrate and a microstrip sum-difference network attached to the dielectric substrate. The dielectric substrate is fixedly connected to the reverse side of the back cavity layer. The microstrip sum-difference network is attached to the side of the dielectric substrate that is not connected to the back cavity layer. The output port of the microstrip sum-difference network is connected to the output terminal K1. The input ports of the microstrip sum-difference network are respectively connected to the first array port, the second array port, the third array port, and the fourth array port.

[0012] Preferably, the microstrip sum-difference network includes a first circulator, a second circulator, a third circulator, and a fourth circulator with identical structures. Each circulator has a first microstrip port, a second microstrip port, a third microstrip port, and a fourth microstrip port. The second and fourth microstrip ports of the first circulator are respectively connected to the first microstrip ports of the third circulator and the first microstrip ports of the fourth circulator. The second and fourth microstrip ports of the second circulator are respectively connected to the third microstrip ports of the third circulator and the third microstrip ports of the fourth circulator. The first and third microstrip ports of the first and second circulators are the four input ports of the microstrip sum-difference network, which are respectively connected to the first array port, the second array port, the third array port, and the fourth array port. The second and fourth microstrip ports of the third and fourth circulators are the four output ports of the microstrip sum-difference network, which are respectively connected to the output terminals.

[0013] Preferably, the first microstrip port and the third microstrip port are input with equal amplitude and in phase, the second microstrip port outputs the sum of the equal amplitude and in phase of the first microstrip port and the third microstrip port, and the fourth microstrip port outputs the sum of the equal amplitude and out-of-phase of the first microstrip port and the third microstrip port.

[0014] Preferably, among the four array ports—the first array port, the second array port, the third array port, and the fourth array port—when any two of the array ports have equal amplitude and are in phase, it is defined as their sum; when any two of the array ports have equal amplitude and are out of phase, it is defined as their difference.

[0015] When the four array ports are fed with equal amplitude and in phase, the output is the sum of the four array ports, which is defined as the sum beam port;

[0016] When the first array port and the second array port are in phase, and the third array port and the fourth array port are in phase, and at the same time, the first array port and the third array port are equal in amplitude and out of phase, and the second array port and the fourth array port are equal in amplitude and out of phase, the output is the sum of the first array port and the second array port, minus the difference between the sum of the third array port and the fourth array port, which is defined as the pitch difference port.

[0017] When the first array port and the third array port are in phase, and the second array port and the fourth array port are in phase, and at the same time, the first array port and the second array port are in phase with equal amplitude and opposite phase, and the third array port and the fourth array port are in phase with equal amplitude and opposite phase, the output is the sum of the first array port and the third array port, minus the difference between the sum of the second array port and the fourth array port, which is defined as the horizontal difference port.

[0018] When the first array port and the fourth array port are in phase, and the second array port and the third array port are in phase, and simultaneously, the first array port and the second array port are in phase with equal amplitude and out of phase, and the fourth array port and the third array port are in phase with equal amplitude and out of phase, the output is the sum of the first array port and the fourth array port, minus the difference between the sum of the second array port and the third array port, which is defined as a dual-difference port.

[0019] Preferably, the phase difference between the horizontal differential aperture and the pitch differential aperture is 180°, and the phase difference change caused by frequency offset is:

[0020]

[0021] Maximum difference beam null offset angle:

[0022]

[0023] Where θ is the pitch angle. Let f be the azimuth angle, 'a' represents the inverse function, i.e., asin() is equal to arcsin(), f H f represents the highest frequency within the bandwidth. L λ represents the lowest frequency within the bandwidth, λ0 represents the wavelength, and d1 represents the distance between the two feed sources.

[0024] The present invention provides an X-band direction-finding antenna device, including the X-band direction-finding antenna and an antenna support. The antenna support includes a horizontally arranged base and two vertically arranged support plates. The two support plates are arranged on two opposite edges of the base. The support plates gradually widen from top to bottom and have multiple hollow holes. The antenna is arranged between the two support plates.

[0025] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows: (1) The present invention sets the X-band direction finding antenna in a multi-layer stacked form, with insulators used for feeding between different layers. This is different from the traditional surface microstrip feeding, which increases the flexibility of the feeding port setting and also abandons the 50-ohm coaxial cable interconnection method that occupies a lot of connection space. This allows the multi-layer structure to be tightly interconnected, greatly reducing the size of the antenna and making the integration degree of the X-band direction finding antenna higher. It also reduces the size and weight of the X-band direction finding antenna, realizing the miniaturization and lightweighting of the antenna; (2) The present invention has a small standing wave ratio and high unit radiation efficiency in the X-band. Specifically, the antenna array unit is a microstrip cavity structure, using microstrip coupled feeding, such as Figure 5 As shown, a coordinate system is established with the center of the entire array as the origin, OA as the horizontal axis, OB as the vertical axis, and the OC axis perpendicular to the array and pointing towards the direction of maximum radiation. The array element is located at the C=0 section, and the OAC plane is defined as the horizontal plane and the OBC plane as the elevation plane. The element polarization is linear polarization in the OB direction. Combined with the coordinate definition, this polarization is vertical polarization, which can achieve a relatively small VSWR and an element radiation efficiency of over 90% in the X-band. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an embodiment of the X-band direction-finding antenna of the present invention;

[0027] Figure 2 yes Figure 1 A schematic diagram of the rear side of the embodiment shown;

[0028] Figure 3 yes Figure 1 An exploded view of the embodiment shown;

[0029] Figure 4 This is a schematic diagram of the front of the array layer in another embodiment of the X-band direction-finding antenna of the present invention;

[0030] Figure 5 This is a schematic diagram of the array layer in another embodiment of the X-band direction-finding antenna of the present invention;

[0031] Figure 6 This is a schematic diagram of the microstrip sum and difference network in another embodiment of the X-band direction-finding antenna of the present invention;

[0032] Figure 7 This is a schematic diagram of the circulator in another embodiment of the X-band direction-finding antenna of the present invention;

[0033] Figure 8 This is a schematic diagram of the connection relationship between the network layer and the array layer in another embodiment of the X-band direction-finding antenna of the present invention;

[0034] Figure 9 This is another embodiment of the X-band direction-finding antenna of the present invention and its 3D beam pattern;

[0035] Figure 10 This is a 3D beam pattern of elevation difference beam in another embodiment of the X-band direction-finding antenna of the present invention;

[0036] Figure 11 This is a 3D beam pattern of the horizontal difference beam in another embodiment of the X-band direction-finding antenna of the present invention;

[0037] Figure 12 This is a 3D radiation pattern of a double-difference beam in another embodiment of the X-band direction-finding antenna of the present invention;

[0038] Figure 13 This is a schematic diagram of the standing wave ratio in another embodiment of the X-band direction-finding antenna of the present invention;

[0039] Figure 14 This is another embodiment of the X-band direction-finding antenna of the present invention and its 2D beam pattern;

[0040] Figure 15 This is a 2D pattern of the horizontal difference beam in another embodiment of the X-band direction-finding antenna of the present invention;

[0041] Figure 16 This is a 2D pattern of the elevation difference beam in another embodiment of the X-band direction-finding antenna of the present invention;

[0042] Figure 17 This is a simulation diagram of another embodiment of the X-band direction-finding antenna of the present invention and the beam amplitude difference reduction beam (amplitude difference);

[0043] Figure 18 This is a simulation diagram of another embodiment of the X-band direction-finding antenna of the present invention and the beam-to-elevation beam (amplitude difference);

[0044] Figure 19 This is a simulation diagram of the beam-to-beam phase difference (phase difference) beam and beam reduction level difference in another embodiment of the X-band direction-finding antenna of the present invention;

[0045] Figure 20 This is a simulation diagram of another embodiment of the X-band direction finding antenna of the present invention and the beam-to-elevation difference beam (phase difference). Detailed Implementation

[0046] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0047] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0048] In the attached diagram, arrow X indicates the front direction (front-to-back), arrow Y indicates the side direction (left-to-right), and arrow Z indicates the vertical direction (up-down).

[0049] Combination Figures 1 to 5 The X-band direction-finding antenna device 100 includes an X-band direction-finding antenna 110 and an antenna support 120. The X-band direction-finding antenna 110 is mounted on the antenna support 120. The X-band direction-finding antenna 110 includes an array layer 1, a cavity layer 2, and a network layer 3 stacked sequentially from front to back. An antenna array is mounted on the array layer 1, and an array port 10 is mounted on the antenna array. The array port 10 is connected to the network layer 3 and an output terminal K1 mounted on the X-band direction-finding antenna 110 through the cavity layer 2. The output terminal K1 is connected to an external device. Through the multi-layer stacking of the X-band direction-finding antenna 110, the integration level of the X-band direction-finding antenna is higher, and the size of the X-band direction-finding antenna is reduced, thus achieving antenna miniaturization.

[0050] Preferably, the X-band direction finding antenna has a length of 222mm, a width of 222mm, and a height of 17.8mm, which meets the requirements for miniaturization.

[0051] This antenna is used for X-band direction finding, covering the frequency band of 8.9–9.9 GHz.

[0052] Preferred, combined Figures 3 to 5The array layer 1 includes a dielectric substrate, an antenna array disposed on the dielectric substrate, and array ports 10 disposed on the antenna array. The antenna array includes a first antenna array element Y1, a second antenna array element Y2, a third antenna array element Y3, and a fourth antenna array element Y4 arranged in quadrants. The array ports 10 include a first array port 101, a second array port 102, a third array port 103, and a fourth array port 104. Each array port is located at the center of its respective antenna array element; that is, the first array port 101 is located at the center of the first antenna array element Y1, the second array port 102 is located at the center of the second antenna array element Y2, the third array port 103 is located at the center of the third antenna array element Y3, and the fourth array port 104 is located at the center of the fourth antenna array element Y4. Through holes are provided on the dielectric substrate at positions corresponding to the first array port 101, the second array port 102, the third array port 103, and the fourth array port 104 for insulator probes to pass through the back cavity layer.

[0053] Preferred, combined Figure 4 Each antenna array element has an array microstrip line, which includes a horizontally arranged transverse microstrip line 11, a vertically arranged vertical microstrip line 12, and a microstrip unit 13. The transverse microstrip line 11 is symmetrically arranged on both sides of the vertical microstrip line 12 and connected to the vertical microstrip line. The microstrip unit 13 is arranged on the transverse microstrip line 11.

[0054] The best, then combined Figure 3 and Figure 5 Multiple coupling feed slots 21 are formed on the coupling surface between the back cavity layer 2 and the array layer 1. In the front-to-back direction, the positions of the coupling feed slots 21 and the microstrip units 13 correspond one-to-one. A coordinate system is established with the center of the array layer 1 as the origin. The OA axis is parallel to one side of the array layer 1, the OB axis is parallel to the other side of the array layer 1, and the OA axis and the OB axis are perpendicular to each other. The OC axis is perpendicular to the array layer 1 and points to the maximum radiation direction. The OAC plane is defined as the horizontal plane, and the OBC plane is defined as the elevation plane. The array microstrip line and the back cavity layer are fed by microstrip coupling. The polarization mode is linear polarization, that is, linear polarization in the OB direction. Combined with the above coordinate definition, this polarization is vertical polarization, which can achieve a standing wave ratio of less than 2.0 in the 8.6-9.9 GHz range and a unit radiation efficiency of more than 90%. The above OA axis, OB axis and OC axis are coordinate systems established for the convenience of understanding the radiation direction. They are different from the coordinate systems of the X, Y and Z axes in the attached figure. That is, the two are different coordinate systems.

[0055] Four insulator probes are installed at positions corresponding to the four array ports 101, 102, 103, and 104 on the back cavity layer. The insulator probes pass through the back cavity layer, and their two ends are connected to the four array ports of array layer 1 and the four input ports of network layer 3, respectively, forming a power supply from array layer 1 to network layer 3. The four output ports of network layer 3 are connected to the output terminal K1 through cables.

[0056] The array microstrip lines are attached to the dielectric substrate of the array layer 1, which is a Rogers 3003 / 0.254mm microwave substrate. The microwave substrate is screwed (or welded) to the front side of the back cavity layer 2.

[0057] Preferred, combined Figure 3 The back cavity layer 2 is closely attached to the array layer 1 mentioned above. The back cavity layer 2 is a metal back cavity, and the material is aluminum of grade 6061. The metal back cavity is formed in the radiation area, which can increase the relative bandwidth of the standing wave by more than 20% (the typical bandwidth of a single-layer microstrip is within 5%). The metal back cavity has a coupling feed slot 21.

[0058] The best, then combined Figure 3 and Figure 6 The network layer 3 includes a dielectric substrate and a microstrip sum-difference network attached to the dielectric substrate. The dielectric substrate is screwed or soldered to the reverse side of the back cavity layer 2. The microstrip sum-difference network is attached to the side of the dielectric substrate that is not connected to the back cavity layer 2. The four output ports of the microstrip sum-difference network are respectively connected to the output terminal K1 through cables. One end of the cable is soldered to the output port of the microstrip sum-difference network, and the other end is connected to the output terminal of the antenna. The dielectric substrate is Rogers3003 / 0.508mm microwave substrate. The first array port 101, the second array port 102, the third array port 103 and the fourth array port 104 are connected through the microstrip sum-difference network.

[0059] Preferred, combined Figure 6 , Figure 7 and Figure 8The microstrip sum-difference network includes a first circulator 31, a second circulator 32, a third circulator 33, and a fourth circulator 34 with identical structures. Each circulator is a circular microstrip line with a first microstrip port S1, a second microstrip port S2, a third microstrip port S3, and a fourth microstrip port S4. That is, the circular microstrip line has four microstrip ports. The first microstrip port S1 and the third microstrip port S3 are input with equal amplitude and in phase. The second microstrip port S2 outputs the sum of the first microstrip port S1 and the third microstrip port S3 with equal amplitude and in phase, i.e., S1+S3. The fourth microstrip port S4 outputs the sum of the first microstrip port S1 and the third microstrip port S3 with equal amplitude and out of phase, i.e., S1-S3. Specifically, the second microstrip port S2 of the first circulator is connected to the first microstrip port S1 of the third circulator, and the fourth microstrip port S4 of the first circulator is connected to the first microstrip port S1 of the fourth circulator; the second microstrip port S2 of the second circulator is connected to the third microstrip port S3 of the third circulator, and the fourth microstrip port S4 of the second circulator is connected to the third microstrip port S3 of the fourth circulator. The four circulators are connected by microstrip lines. The first microstrip ports S1 and S3 of the first circulator, and the first microstrip ports S1 and S3 of the second circulator are the four components of network layer 3. The input ports are connected to the first array port 101, second array port 102, third array port 103, and fourth array port 104 corresponding to the first antenna array unit Y1, the second antenna array unit Y2, the third antenna array unit Y3, and the fourth antenna array unit Y4 on array layer 1, respectively, via insulator probes; the second microstrip port S2 and the fourth microstrip port S4 of the third circulator, and the second microstrip port S2 and the fourth microstrip port S4 of the fourth circulator are the four output ports K11, K12, K13, and K14 of network layer 3, respectively, and are connected to the output terminal K1 via cables.

[0060] Preferably, among the four array ports—first array port 101, second array port 102, third array port 103, and fourth array port 104—when any two array ports have equal amplitude and are in phase, it is defined as their sum; when any two array ports have equal amplitude and are out of phase, it is defined as their difference. Combined with... Figure 8 The first array port 101, the second array port 102, the third array port 103 and the fourth array port 104 are named A, B, C and D respectively.

[0061] When all four array ports are fed with equal amplitude and in phase, the output is the sum of the four array ports, i.e., A+B+C+D, defined as the sum beam. Each antenna array element has a gain of 20dBi and a beamwidth of 15°. The sum beam is the sum of the gain of the four antenna array elements with equal amplitude and in phase, resulting in a gain of 26.8dBi and a beamwidth of 9°. The gain is maximum at theta = 0°, where the received signal is strongest. The 3D radiation pattern of the sum beam (A+B+C+D) is shown below. Figure 9 As shown.

[0062] When the first array port 101 and the second array port 102 are of equal amplitude and in phase (i.e., A and B are in phase), and the third array port 103 and the fourth array port 104 are of equal amplitude and in phase (i.e., C and D are in phase), and simultaneously, the first array port 101 and the third array port 103 are of equal amplitude but out of phase (i.e., A and C are of equal amplitude but out of phase), and the second array port 102 and the fourth array port 104 are of equal amplitude but out of phase (i.e., B and D are of equal amplitude but out of phase), the output is the sum of the first array port 101 and the second array port 102, minus the difference between the sum of the third array port 103 and the fourth array port 104, which is (A+B)-(C+D), defined as the pitch difference beam. The 3D radiation pattern of the pitch difference beam ((A+B)-(C+D)) is as follows: Figure 10 As shown.

[0063] When the first array port 101 and the third array port 103 are of equal amplitude and in phase (i.e., A and C are in phase), and the second array port 102 and the fourth array port 104 are of equal amplitude and in phase (i.e., B and D are in phase), and simultaneously, the first array port 101 and the second array port 102 are of equal amplitude but out of phase (i.e., A and B are of equal amplitude but out of phase), and the third array port 103 and the fourth array port 104 are of equal amplitude but out of phase (i.e., C and D are of equal amplitude but out of phase), the output is the sum of the first array port 101 and the third array port 103, minus the difference between the sum of the second array port 102 and the fourth array port 104, which is (A+C)-(B+D), defined as the horizontal difference beam. The 3D radiation pattern of the horizontal difference beam ((A+C)-(B+D)) is as follows. Figure 11 As shown.

[0064] When the first array port 101 and the fourth array port 104 are of equal amplitude and in phase (i.e., A and D are in phase), and the second array port 102 and the third array port 103 are of equal amplitude and in phase (i.e., B and C are in phase), and simultaneously, the first array port 101 and the second array port 102 are of equal amplitude but out of phase (i.e., A and B are of equal amplitude but out of phase), and the fourth array port 104 and the third array port 103 are of equal amplitude but out of phase (i.e., C and D are of equal amplitude but out of phase), the output is the sum of the first array port 101 and the fourth array port 104, minus the difference between the sum of the second array port 102 and the third array port 103, which is (A+D)-(B+C), defined as a dual-difference port. The 3D radiation pattern of the dual-difference beam ((A+D)-(B+C)) is as follows. Figure 12 As shown.

[0065] In practical applications, the antenna alternates between the sum beam and the difference beam. The location of the target is where the sum beam receives the strongest signal and the difference beam receives the weakest signal.

[0066] Preferably, the phase difference between the horizontal differential aperture and the pitch differential aperture is 180°, and the phase difference change caused by frequency offset is:

[0067]

[0068] Maximum difference beam null offset angle:

[0069]

[0070] Where θ is the pitch angle. Let f be the azimuth angle, 'a' represents the inverse function, i.e., asin() is equal to arcsin(), f H f represents the highest frequency within the bandwidth. L λ represents the lowest frequency within the bandwidth, λ0 represents the wavelength, and d1 represents the distance between the two feed sources.

[0071] Preferably, the cable is a 50-ohm coaxial cable, which is side-fed when soldered to the microstrip and differential network.

[0072] Preferably, the antenna bracket 120 includes a horizontally arranged base 121 and two vertically arranged support plates 122. The two support plates 122 are arranged on two opposite edges of the base 121. The support plates 122 gradually widen from top to bottom, and multiple hollow holes 1221 are opened on the support plates 122. The antenna body 110 is arranged between the two support plates 122 and is screwed to the support plates 122 by bolts or screws.

[0073] Preferably, a triangular bracket 123 is provided on the side of the support plate 122. The triangular bracket 123 is triangular, with one right-angled side of the triangular bracket 123 supporting and abutting the edge of the support plate 122, and the other right-angled side of the triangular bracket 123 supporting and abutting the base 121, thereby strengthening the stability of the connection between the support plate 122 and the base 121, and making the support of the support plate 122 more stable.

[0074] like Figure 13 As shown, direction finding can be performed using sum and difference beams within a frequency band where the standing wave ratio is less than 2.0.

[0075] like Figure 14 As shown, the antenna and beam pattern are 2D. It can be seen that the simulated gain is greater than 17 dBi and the beamwidth is greater than 18 degrees within the antenna bandwidth.

[0076] like Figure 15 and Figure 16 As shown, the zero depth of the differential beam normal is -5 to -10 dBi, and the differential beam frequency offset angle is about 1 degree.

[0077] like Figure 17 and Figure 18 As shown, within a range of ±20 degrees, the amplitude difference of the sum and difference beams ranges from -20dB to +20dB. Based on a receiver amplitude resolution of 0.5dB, the angle measurement error should be less than 1 degree (after accurate calibration).

[0078] like Figure 19 and Figure 20 As shown, the phase difference of the sum and difference beam jumps by about 180 degrees on both sides of the normal of the array surface, and the phase maintains a significant difference within a range of ±20 degrees, which can be used for left, right or up and down position discrimination.

[0079] Before using the sum and difference beam to measure direction, the general direction should be determined using the sum beam beforehand. Only when the angle of deviation of the incoming wave direction from the normal of the array surface is within ±20 degrees can the sum and difference beam be used to calculate the direction.

[0080] Based on the above embodiments, an X-band direction-finding antenna of the present invention includes an array layer, a cavity layer, and a network layer stacked sequentially from front to back. The array layer has at least one antenna array element and array ports corresponding to each antenna array element. The array ports pass through the cavity layer and connect to the network layer and an output terminal disposed on the antenna body. This X-band direction-finding antenna has a high degree of integration, small size, and light weight, achieving miniaturization. Simultaneously, it exhibits a low standing wave ratio and high element radiation efficiency in the X-band. An X-band direction-finding antenna device includes an X-band direction-finding antenna and an antenna bracket for fixing the antenna.

Claims

1. An X-band direction finding antenna, characterized by The system comprises an array layer, a cavity layer, and a network layer stacked sequentially from front to back. An antenna array is disposed on the array layer, and array ports are provided on the antenna array. The array ports are connected to the network layer and an output terminal disposed on the antenna through the cavity layer. The antenna array includes a first antenna array element, a second antenna array element, a third antenna array element, and a fourth antenna array element arranged in quadrants. The array ports include a first array port, a second array port, a third array port, and a fourth array port, each array port being respectively disposed at the center of its respective antenna array element. Multiple coupling feed slots are formed on the coupling surface between the cavity layer and the array layer. In the front-to-back direction, the coupling feed slots correspond one-to-one with the positions of the microstrip units on the antenna array. Four insulator probes are set at the positions corresponding to the four array ports on the cavity layer. The insulator probes pass through the cavity layer and their two ends are connected to the four array ports of the array layer and the four input ports of the network layer, respectively, forming a feed from the array layer to the network layer. The network layer includes a dielectric substrate and a microstrip sum-difference network attached to the dielectric substrate. The dielectric substrate is fixedly connected to the reverse side of the back cavity layer. The microstrip sum-difference network is attached to the side of the dielectric substrate that is not connected to the back cavity layer. The output port of the microstrip sum-difference network is connected to the output terminal. The input port of the microstrip sum-difference network is connected to the first array port, the second array port, the third array port, and the fourth array port, respectively. The microstrip sum-difference network comprises four identical circulators: a first circulator, a second circulator, a third circulator, and a fourth circulator. Each circulator has four microstrip ports. The first and third microstrip ports are inputs with equal amplitude and in phase. The second microstrip port outputs the sum of the equal amplitude and in phase values ​​of the first and third microstrip ports. The fourth microstrip port outputs the sum of the equal amplitude and out-of-phase values ​​of the first and third microstrip ports. Specifically, the second microstrip port of the first circulator is connected to the first microstrip port of the third circulator, and the fourth microstrip port of the first circulator is connected to the first microstrip port of the fourth circulator. Similarly, the second microstrip port of the second circulator is connected to the third microstrip port of the third circulator, and the fourth microstrip port of the second circulator is connected to the fourth microstrip port. The circulators are connected to their third microstrip ports, and the four circulators are connected to each other via microstrip lines. The first and third microstrip ports of the first circulator, and the first and third microstrip ports of the second circulator are the four input ports of the network layer, and are respectively connected to the first, second, third, and fourth array ports of the first, second, third, and fourth antenna array units on the array layer via insulator probes. The second and fourth microstrip ports of the third circulator, and the second and fourth microstrip ports of the fourth circulator are the four output ports of the network layer, and are respectively connected to the output terminals via cables.

2. The X-band direction finding antenna of claim 1, wherein, Each antenna array element has an array microstrip line, which includes a horizontally arranged transverse microstrip line, a vertically arranged vertical microstrip line, and microstrip units. The transverse microstrip line is arranged on both sides of the vertical microstrip line and connected to the vertical microstrip line. The microstrip units are arranged on the transverse microstrip line.

3. The X-band direction finding antenna of claim 1, wherein, Among the four array ports—the first array port, the second array port, the third array port, and the fourth array port—when any two of the array ports have equal amplitude and are in phase, it is defined as their sum; when any two of the array ports have equal amplitude and are out of phase, it is defined as their difference. When the four array ports are fed with equal amplitude and in phase, the output is the sum of the four array ports, which is defined as the sum beam port; When the first array port and the second array port are in phase, and the third array port and the fourth array port are in phase, and at the same time, the first array port and the third array port are equal in amplitude and out of phase, and the second array port and the fourth array port are equal in amplitude and out of phase, the output is the sum of the first array port and the second array port, minus the difference between the sum of the third array port and the fourth array port, which is defined as the pitch difference port. When the first array port and the third array port are in phase, and the second array port and the fourth array port are in phase, and at the same time, the first array port and the second array port are in phase with equal amplitude and opposite phase, and the third array port and the fourth array port are in phase with equal amplitude and opposite phase, the output is the sum of the first array port and the third array port, minus the difference between the sum of the second array port and the fourth array port, which is defined as the horizontal difference port. When the first array port and the fourth array port are in phase, and the second array port and the third array port are in phase, and simultaneously, the first array port and the second array port are in phase with equal amplitude and out of phase, and the fourth array port and the third array port are in phase with equal amplitude and out of phase, the output is the sum of the first array port and the fourth array port, minus the difference between the sum of the second array port and the third array port, which is defined as a dual-difference port.

4. The X-band direction finding antenna of claim 3, wherein, The phase difference between the horizontal and vertical differential apertures is 180°, and the change in phase difference due to frequency offset is: ； Maximum difference beam null offset angle: ； in, The pitch angle, It is the azimuth angle. Indicates the inverse function, i.e. for , Indicates the highest frequency within the bandwidth. Indicates the lowest frequency within the bandwidth. Indicates wavelength. This indicates the distance between the two feed sources.

5. An X-band direction-finding antenna device, characterized in that, The antenna includes the X-band direction finding antenna according to any one of claims 1 to 4, and further includes an antenna bracket. The antenna bracket includes a horizontally arranged base and two vertically arranged support plates. The two support plates are arranged on two opposite edges of the base. The support plates gradually widen from top to bottom and have multiple hollow holes. The antenna is arranged between the two support plates.

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