A dual-band 4x4 butler matrix based on branch loaded resonators

Abstract

This invention discloses a dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator, comprising a first dual-frequency filtering 180° coupler, a second dual-frequency filtering 180° coupler, a first broadband 90° coupler, a second broadband 90° coupler, a first broadband 90° phase shifter, a second broadband 90° phase shifter, and a third broadband 90° phase shifter, all placed on the top layer of a dielectric substrate; a metal base plate on the bottom layer of the dielectric substrate; and eight disks connected to SMP (Short-Side Multi-Pack) devices, with each disk corresponding to an input / output port on the top layer of the dielectric substrate. Based on the modified Butler matrix topology, a dual-frequency filtering 180° coupler is designed, enabling the Butler matrix to achieve dual-frequency filtering functionality. This invention exhibits excellent dual-frequency bandpass filtering characteristics and has the advantages of being single-layered, small in size, simple in structure, and easy to fabricate.

Description

Technical Field

[0001] This invention belongs to the field of beamforming network technology, specifically relating to a dual-frequency filtering 4×4 Butler matrix based on a stub-loaded resonator. Background Technology

[0002] With the rapid development of wireless communication technology, smart antennas are receiving increasing attention, as simple directional radiating antennas are no longer sufficient to meet the demands of antenna intelligence. Multi-beam antennas can generate multiple independently pointing beams at different scanning angles. Due to their strong anti-interference capabilities and large beam coverage, they are widely used in military fields such as radar systems and satellite communication systems. The key to multi-beam antennas lies in the beamforming network, which is a feeding network with multiple input and output ports. Signals are input through a specific input port, power is distributed within the feeding network, and a constant phase difference is generated between adjacent output ports. By combining a beamforming network with an array antenna, the antenna pattern differs depending on the input phase difference, thus achieving multi-beaming. The Butler matrix is ​​one of the important beamforming networks. It has a balanced current path, is perfectly matched, requires the fewest couplers compared to other beamforming network matrices, and the beams formed by the Butler matrix are orthogonal. Therefore, the Butler matrix has great application potential as a beamforming network.

[0003] With increasing demands for system stability and bandwidth utilization, dual-band operation is often considered reliable. In unmanned sensing systems, when the detection distance exceeds the detection range of one frequency in a dual-band system, the other frequency can supplement it, significantly improving system reliability. Simultaneously, dual-band systems operate on two frequency bands but share a single physical aperture, effectively reducing system size. Therefore, dual-band systems have great application potential in the wireless field. Filters are an indispensable part of the system, effectively filtering out various unwanted signals and noise signals from amplifiers and other devices, playing a crucial role in ensuring normal system operation and improving system reliability. In multi-beam antenna systems, filters are typically cascaded with Butler matrices, but this increases system size and hinders miniaturization. Therefore, a design method integrating filtering functions into the Butler matrix is ​​needed to reduce system size while increasing system anti-interference capabilities.

[0004] Therefore, existing beamforming network technology makes it difficult to design a dual-frequency, integrated filter function Butler matrix, which is insufficient to meet the needs of multi-beam systems in radar and unmanned sensing fields. Summary of the Invention

[0005] The present invention aims to provide a dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator, which solves the problems of poor integration, complex structure and large size of existing dual-frequency filtering Butler matrices.

[0006] The technical solution to achieve the purpose of this invention is as follows: a dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator, comprising a first dual-frequency filtering 180° coupler, a second dual-frequency filtering 180° coupler, a first broadband 90° coupler, a second broadband 90° coupler, a first broadband 90° phase shifter, a second broadband 90° phase shifter, a third broadband 90° phase shifter, input port one, input port two, input port three, input port four, output port five, output port six, output port seven, and output port eight, and a metal layer on the bottom layer of the dielectric substrate. The system consists of a base plate and eight SMP (Surface Mount Multi-Pulse) disks, each corresponding to an input / output port on the top layer of the dielectric substrate. Input port one connects to input port seven of the first dual-frequency filter 180° coupler. Output port ten of the first dual-frequency filter 180° coupler is connected to input port five of the second broadband 90° coupler via a first transmission line. Output port three of the second broadband 90° coupler is connected to output port five via a second transmission line. Input port two connects to input port six of the first dual-frequency filter 180° coupler. Output port three of the first dual-frequency filter 180° coupler is connected to input port five via a third transmission line. The first broadband 90° coupler's input port 5 is connected to the first broadband 90° coupler's output port 3 via the fourth transmission line, which is then connected to the output port 6. Input port 3 is connected to the second dual-frequency filter 180° coupler's input port 7 via the fifth transmission line, which is then connected to the second broadband 90° coupler's input port 8 via the fifth transmission line. The second broadband 90° coupler's output port 4 is connected to the third broadband 90° phase shifter's input port 9 via the sixth transmission line, which is then connected to the third broadband 90° phase shifter's input port 9 via the seventh transmission line. Output port seven; input port four is connected to input port six of the second dual-frequency filter 180° coupler; output port three of the second dual-frequency filter 180° coupler is connected to input port nine of the second broadband 90° phase shifter via transmission line eight; output port nine of the second broadband 90° phase shifter is connected to input port eight of the first broadband 90° coupler via transmission line nine; output port four of the first broadband 90° coupler is connected to input port nine of the first broadband 90° phase shifter via transmission line ten; and output port nine of the first broadband 90° phase shifter is then connected to output port eight via transmission line eleven.

[0007] Preferably, when input ports 1, 2, 3, and 4 are input respectively, output ports 5, 6, 7, and 8 output signals with different phase differences. When input port 1 is input, the signal amplitudes of output ports 5, 6, 7, and 8 are equal and have a 0° phase difference. When input port 2 is input, the signal amplitudes of output ports 5, 6, 7, and 8 are equal and have a 180° phase difference. When input port 3 is input, the signal amplitudes of output ports 5, 6, 7, and 8 are equal and have a 90° phase difference. When input port 4 is input, the signal amplitudes of output ports 5, 6, 7, and 8 are equal and have a -90° phase difference.

[0008] Preferably, the first dual-frequency filtering 180° coupler and the second dual-frequency filtering 180° coupler have the same structure and size; the first dual-frequency filtering 180° coupler includes a first SLR, a second SLR, a third SLR, and a fourth SLR. The first SLR and the second SLR have the same size and are placed in the same direction, while the third SLR and the fourth SLR have the same size but are placed in opposite directions. The input port seven is coupled to the first SLR via a microstrip line segment. The signal is divided into two parts: one part is coupled to the second SLR via electrical coupling, and then coupled to the microstrip line segment to be transmitted to the output port three; the other part is transmitted to the third SLR via electromagnetic hybrid coupling, and then coupled to the microstrip line segment to be transmitted to the output port ten.

[0009] The input port six is ​​coupled to the fourth SLR via a microstrip line segment. The signal here is divided into two parts: one part is coupled to the second SLR via electromagnetic hybrid coupling, and then coupled to the microstrip line segment to be transmitted to the output port three; the other part is transmitted to the third SLR via magnetic coupling, and then coupled to the microstrip line segment to be transmitted to the output port ten.

[0010] When input port seven is used, the signals output from output ports three and ten have dual-bandpass filtering characteristics, and the output signals have the same phase and amplitude; when input port six is ​​used, the signals output from output ports three and ten have dual-bandpass filtering characteristics, the output signals have the same amplitude, and there is a 180° phase difference.

[0011] Preferably, the first and second broadband 90° couplers have the same structure and size, and are both four-branch directional couplers. The first broadband 90° coupler includes input port five, input port eight, output port three, output port four, a first microstrip transmission line, a second microstrip transmission line, a third microstrip transmission line, a fourth microstrip transmission line, a fifth microstrip transmission line, a sixth microstrip transmission line, a seventh microstrip transmission line, an eighth microstrip transmission line, a ninth microstrip transmission line, and a tenth microstrip transmission line. The first, second, third, and fourth microstrip transmission lines have the same size, the fifth and sixth microstrip transmission lines have the same size, and the seventh and tenth microstrip transmission lines have the same size. The eight microstrip transmission lines are of the same size, and the ninth and tenth microstrip transmission lines are of the same size. Input port five is connected to output port three via the first, fifth, and second microstrip transmission lines respectively; input port eight is connected to output port four via the third, sixth, and fourth microstrip transmission lines respectively; the first and third microstrip transmission lines are connected at their ends via the seventh and ninth microstrip transmission lines respectively; the fifth and sixth microstrip transmission lines are connected at their ends via the ninth and tenth microstrip transmission lines respectively; and the second and fourth microstrip transmission lines are connected at their ends via the tenth and eighth microstrip transmission lines respectively.

[0012] When input port five is used, the signal amplitudes output by output port three and output port four are equal, but the phase of the output signal of output port three leads that of output port four by 90°; when input port eight is used, the signal amplitudes output by output port three and output port four are equal, but the phase of the output signal of output port three lags that of output port four by 90°.

[0013] Preferably, the first broadband 90° phase shifter, the second broadband 90° phase shifter, and the third broadband 90° phase shifter have the same structure and the same size. The first broadband 90° phase shifter includes an input port nine, an output port nine, an eleventh microstrip transmission line, a twelfth microstrip transmission line, a thirteenth microstrip transmission line, a first microstrip line with a short-circuited terminal, a second microstrip line, a first grounding metal through-hole, and a second grounding metal through-hole with a symmetrical structure.

[0014] The input port nine is connected to the output port nine in sequence through the eleventh microstrip transmission line, the twelfth microstrip transmission line, and the thirteenth microstrip transmission line; a first microstrip line with a short-circuited termination is connected in parallel between the input port and the eleventh microstrip transmission line, and the short-circuiting termination is achieved through a grounded first grounding metal via; a second microstrip line with a short-circuited termination is connected in parallel between the output port and the thirteenth microstrip transmission line, and the short-circuiting termination is achieved through a grounded second grounding metal via.

[0015] Preferably, the widths of the first transmission line, second transmission line, third transmission line, fourth transmission line, fifth transmission line, sixth transmission line, seventh transmission line, eighth transmission line, ninth transmission line, tenth transmission line, and eleventh transmission line are... , which is the width of a 50Ω microstrip line with a center frequency of 15GHz.

[0016] Compared with the prior art, the significant advantages of this invention are:

[0017] 1. Replace the first set of couplers in the traditional Butler matrix topology with a dual-frequency filtering 180° coupler to provide the Butler network with good dual-frequency bandpass filtering characteristics.

[0018] 2. The second set of couplers in the traditional Butler matrix topology is replaced with a combination of a broadband 90° coupler and a broadband 90° phase shifter, eliminating cross junctions and reducing system complexity.

[0019] 3. The entire network is printed on a single-layer dielectric substrate, which is small in size and easy to process.

[0020] 4. The network adopts a microstrip structure, which is low in cost, small in size and light in weight.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0022] Figure 1 This is a top-level schematic diagram of the dual-frequency filtering 4×4 Butler matrix based on the spur-loaded resonator of this invention.

[0023] Figure 2 This is a schematic diagram of the bottom layer of the dual-frequency filtering 4×4 Butler matrix based on the spur-loaded resonator of the present invention.

[0024] Figure 3 yes Figure 1 Schematic diagram of the dimensions of the first dual-frequency filter 180° coupler 2

[0025] Figure 4 yes Figure 3 S-parameter test diagram of the first dual-frequency filter 180° coupler 2-port 32

[0026] Figure 5 yes Figure 3 S-parameter test diagram of the first dual-frequency filter 180° coupler 2-port 34

[0027] Figure 6 yes Figure 3 Phase test diagram of the first dual-frequency filter 180° coupler 2-port 32

[0028] Figure 7 yes Figure 3 Phase test diagram of the first dual-frequency filter 180° coupler 2-port 34

[0029] Figure 8 yes Figure 1 Schematic diagram of the first broadband 90° coupler 4

[0030] Figure 9 yes Figure 6 S-parameter simulation diagram of the first broadband 90° coupler 4

[0031] Figure 10 yes Figure 6 Phase simulation diagram of the first broadband 90° coupler 4

[0032] Figure 11 yes Figure 1 Schematic diagram of the first broadband 90° phase shifter 6

[0033] Figure 12 yes Figure 9 S-parameter simulation diagram of the first broadband 90° phase shifter 6

[0034] Figure 13 yes Figure 9 Phase simulation diagram of the first broadband 90° phase shifter 6

[0035] Figure 14 This is a topology diagram of the dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator according to the present invention.

[0036] Figure 15 This is a test diagram of the S-parameters of port 9 of a dual-frequency filter 4×4 Butler matrix based on a spur-loaded resonator according to the present invention.

[0037] Figure 16 This is a test diagram of the S-parameters of port 10 of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator of the present invention.

[0038] Figure 17 This is the S-parameter test diagram of port 11 of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator of the present invention.

[0039] Figure 18 This is the S-parameter test diagram of port 12 of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator of the present invention.

[0040] Figure 19 This is a phase test diagram of port 9 of a dual-frequency filter 4×4 Butler matrix based on a spur-loaded resonator according to the present invention.

[0041] Figure 20This is a phase test diagram of port 10 of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator of the present invention.

[0042] Figure 21 This is a phase test diagram of port 11 of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator of the present invention.

[0043] Figure 22 This is a phase test diagram of port 12 of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator of the present invention. Detailed Implementation

[0044] like Figure 1 As shown, a dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator has the following components on the top layer of the dielectric substrate 1: a first dual-frequency filtering 180° coupler 2, a second dual-frequency filtering 180° coupler 3, a first broadband 90° coupler 4, a second broadband 90° coupler 5, a first broadband 90° phase shifter 6, a second broadband 90° phase shifter 7, a third broadband 90° phase shifter 8, an input port 1 9, an input port 2 10, an input port 3 11, an input port 4 12, an output port 5 24, an output port 6 25, an output port 7 26, and an output port 8 27.

[0045] like Figure 2 As shown, there is a metal base plate 63 on the bottom layer of the dielectric substrate 1, and 8 disks 64 corresponding to ports 9~12 and 24~27 for connecting to SMP.

[0046] Preferably, the dielectric substrate 1 is Rogers RT / duroid 5880, with a relative permittivity of 2.2 and a thickness of 0.508 mm.

[0047] like Figure 1As shown, input port 19 is connected to the first dual-frequency filter 180° coupler 2, then to the second broadband 90° coupler 5 via the first transmission line 13, and then to output port 24 via the second transmission line 14; input port 20 is connected to the first dual-frequency filter 180° coupler 2, then to the first broadband 90° coupler 4 via the third transmission line 15, and then to output port 25 via the fourth transmission line 16; input port 31 is connected to the second dual-frequency filter 180° coupler 3, and then to the fifth transmission line 17. The signal is transmitted to the second wideband 90° coupler 5, then to the third wideband 90° phase shifter 8 via the sixth transmission line 18, and then to the output port 26 via the seventh transmission line 19; the input port 12 is connected to the second dual-frequency filter 180° coupler 3, then to the second wideband 90° phase shifter 7 via the eighth transmission line 20, then to the first wideband 90° coupler 4 via the ninth transmission line 21, then to the first wideband 90° phase shifter 6 via the tenth transmission line 22, and then to the output port 27 via the eleventh transmission line 23.

[0048] Preferably, the width of the first transmission line 13-23 is It is a 50Ω microstrip linewidth with a center frequency of 15GHz.

[0049] like Figure 1 As shown, in order to ensure the phase of the output signal, the lengths of the first transmission lines 13-23 need to be carefully optimized. The specific lengths of each segment are as follows: , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0050] like Figure 1As shown, the first dual-frequency filter 180° coupler 2 and the second dual-frequency filter 180° coupler 3 have the same structure and size. The structure of the two is explained by taking the first dual-frequency filter 180° coupler 2 as an example.

[0051] like Figure 3 As shown, the first dual-frequency filter 180° coupler 2 includes input port 1 (32), input port 2 (34), output port 3 (36), output port 4 (38), and four segmented resonators bent into a "mountain" shape: SLR28, SLR29, SLR30, and SLR31. SLR28 and SLR29 are the same size and have the same orientation, while SLR30 and SLR31 are the same size but have opposite orientations. Input port 1 (32) is coupled to SLR28 via microstrip line segment 33. The signal is divided into two parts here: one part is coupled to SLR29 via electrical coupling, and then coupled to microstrip line segment 37 to output port 3 (36); the other part is coupled to SLR30 via electromagnetic hybrid coupling, and then coupled to microstrip line segment 39 to output port 4 (38). Input port 2 (34) is coupled to SLR 31 via microstrip segment 35. The signal here is divided into two parts: one part is coupled to SLR 29 via electromagnetic hybrid coupling, then coupled to microstrip segment 37, and transmitted to output port 36; the other part is coupled to SLR 30 via magnetic coupling, then coupled to microstrip segment 39, and transmitted to output port 4 (38). When input port 1 (32) is input, the signals output from output ports 36 and 4 (38) have dual-bandpass filtering characteristics, and the output signals have the same phase and amplitude. When input port 2 (34) is input, the signals output from output ports 36 and 4 (38) have dual-bandpass filtering characteristics, the output signals have the same amplitude, and there is a 180° phase difference.

[0052] Preferably, the SLR28, SLR29, SLR30, and SLR31 have equal widths. .

[0053] like Figure 3 As shown, the specific dimensions of the first dual-frequency filter 180° coupler 2 are as follows: , , , , , , , , , , , , , .

[0054] Figure 4 Figure 5 shows the S-parameter test diagram of the first dual-frequency filter 180° coupler 2, with center frequencies of 12.25 GHz and 17.25 GHz, and a low-frequency bandwidth of 9.1%. ), 11.9% ), with a high-frequency bandwidth of 3.5% ( ), 3.8% ).

[0055] Figures 6-7 This is the phase test diagram of the first dual-frequency filter 180° coupler 2.

[0056] like Figure 1 As shown, the first broadband 90° coupler 4 and the second broadband 90° coupler 5 have the same structure and size, and are both four-branch directional couplers. The structure of the two is explained using the first broadband 90° coupler 4 as an example.

[0057] like Figure 8 As shown, the first broadband 90° coupler 4 is a four-branch directional coupler, including an input port 40, an input port 41, an output port 42, an output port 43, and microstrip transmission lines 44-53. Microstrip transmission lines 44, 46, 47, and 49 are of the same size; microstrip transmission lines 45 and 48 are of the same size; microstrip transmission lines 50 and 53 are of the same size; and microstrip transmission lines 51 and 52 are of the same size. Input port 40 is connected to output port 42 via microstrip transmission lines 44, 45, and 46; input port 41 is connected to output port 43 via microstrip transmission lines 47, 48, and 49; the ends of microstrip transmission lines 44 and 47 are connected via microstrip transmission lines 50 and 51, respectively; the ends of microstrip transmission lines 45 and 48 are connected via microstrip transmission lines 51 and 52, respectively; and the ends of microstrip transmission lines 46 and 49 are connected via microstrip transmission lines 52 and 53, respectively. When input is received at input port 40, the output signal has the same amplitude and output port 42 is 90° ahead of output port 43 in phase; when input is received at input port 41, the output signal has the same amplitude and output port 42 is 90° behind output port 43 in phase.

[0058] like Figure 8 As shown, the specific dimensions of the first broadband 90° coupler 4 are as follows: , , , , , , , .

[0059] Figure 9 10 shows the simulation results of the first broadband 90° coupler 4 in HFSS. Figure 7 The simulation graph shows the S-parameters. Figure 8 This is a phase simulation diagram.

[0060] like Figure 1 As shown, the first broadband 90° phase shifter 6, the second broadband 90° phase shifter 7, and the third broadband 90° phase shifter 8 have the same structure and size. The structure of the three is explained using the first broadband 90° phase shifter 6 as an example.

[0061] like Figure 11 As shown, the first broadband 90° phase shifter 6 includes an input port 54, an output port 55, microstrip transmission lines 56-58, short-circuited microstrip lines 59-60, and grounded metal vias 61-62, with a symmetrical structure. The input port 54 is connected to the output port 55 sequentially through microstrip transmission lines 56-58; a short-circuited microstrip line 59 is connected in parallel between the input port and the microstrip transmission line 56, and the short circuit is achieved through the grounded metal via 61; a short-circuited microstrip line 60 is connected in parallel between the output port and the microstrip transmission line 58, and the short circuit is achieved through the grounded metal via 62.

[0062] like Figure 11 As shown, the specific dimensions of the first broadband 90° phase shifter 6 are as follows: , , , , , , .

[0063] Figure 12 13 shows the simulation results of the first broadband 90° coupler 4 in HFSS. Figure 12 The simulation graph shows the S-parameters. Figure 13 This is a phase simulation diagram.

[0064] Figure 14This is the topology diagram of the dual-frequency filtering 4×4 Butler matrix based on the spur-loaded resonator. P1~P4 are input ports, corresponding to input ports 9~12, and P5~P8 are output ports, corresponding to output ports 24~27. The first dual-frequency filtering 180° coupler 2 and the second dual-frequency filtering 180° coupler 3 are key to the dual-frequency filtering achieved by the Butler matrix. Unlike the traditional Butler matrix topology, this Butler matrix topology does not have a cross-junction structure. The two 180° couplers in the first group of the traditional topology are replaced with dual-frequency filtering 180° couplers 2~3, and the two 180° couplers in the second group of the traditional topology are replaced with a combination of the first wideband 90° coupler 4 and the first wideband 90° phase shifter 6, and a combination of the second wideband 90° coupler 5 and the third wideband 90° phase shifter 8. The phase difference of the outputs from ports P5~P8 is as follows: , , , .

[0065] Figures 15-18 The image shows the S-parameter test results of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator, with center frequencies of 12.25 GHz and 17.25 GHz, and a low-frequency bandwidth of 8.2%. ), 11.1% ), 9% ), 10.4% ), with a high-frequency bandwidth of 3.3% ( ), 3% ), 3.5% ), 3.4% ).

[0066] Figures 19-22 This is the phase test diagram of the dual-frequency filter 4×4 Butler matrix based on the spur-loaded resonator.

Claims

1. A dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator, characterized in that, Includes a first dual-frequency filter 180° coupler (2), a second dual-frequency filter 180° coupler (3), a first broadband 90° coupler (4), a second broadband 90° coupler (5), a first broadband 90° phase shifter (6), a second broadband 90° phase shifter (7), a third broadband 90° phase shifter (8) placed on the top layer of the dielectric substrate (1), an input port one (9), an input port two (10), an input port three (11), an input port four (12), an output port five (24), an output port six (25), an output port seven (26), and an output port eight, all placed on the top layer of the dielectric substrate (1). (27), a metal base plate (63) placed on the bottom layer of the dielectric substrate, eight disks (64) connected to the SMP, the eight disks (64) are arranged one-to-one with the input and output ports set on the top layer of the dielectric substrate (1); input port one (9) is connected to input port seven (32) of the first dual-frequency filter 180° coupler (2), output port ten (38) of the first dual-frequency filter 180° coupler (2) is connected to input port five (40) of the second broadband 90° coupler (5) through the first transmission line (13), and output port three ( 42) Connected to output port five (24) via the second transmission line (14); input port two (10) is connected to input port six (34) of the first dual-frequency filter 180° coupler (2); output port three (36) of the first dual-frequency filter 180° coupler (2) is connected to input port five (40) of the first broadband 90° coupler (4) via the third transmission line (15); output port three (42) of the first broadband 90° coupler (4) is connected to output port six (25) via the fourth transmission line (16); input port three (11) is connected to the second dual-frequency filter The input port 7 (32) of the 180° coupler (3) and the output port 10 (38) of the second dual-frequency filter 180° coupler (3) are connected to the input port 8 (41) of the second broadband 90° coupler (5) via the fifth transmission line (17). The output port 4 (43) of the second broadband 90° coupler (5) is connected to the input port 9 (54) of the third broadband 90° phase shifter (8) via the sixth transmission line (18). The output port 9 (55) of the third broadband 90° phase shifter (8) is connected to the output port 7 (26) via the seventh transmission line (19).Input port four (12) is connected to input port six (34) of the second dual-frequency filter 180° coupler (3). Output port three (36) of the second dual-frequency filter 180° coupler (3) is connected to input port nine (54) of the second broadband 90° phase shifter (7) via transmission line eight (20). Output port nine (55) of the second broadband 90° phase shifter (7) is connected to input port eight (41) of the first broadband 90° coupler (4) via transmission line nine (21). Output port four (43) of the first broadband 90° coupler (4) is connected to input port nine (54) of the first broadband 90° phase shifter (6) via transmission line ten (22). Output port nine (55) of the first broadband 90° phase shifter (6) is then connected to output port eight (27) via transmission line eleven (23).

2. The double frequency filtering 4x4 Butler matrix based on branch loaded resonators according to claim 1, characterized in that, When input ports 1 (9), 2 (10), 3 (11), and 4 (12) are input respectively, output ports 5 (24), 6 (25), 7 (26), and 8 (27) output signals with different phase differences. When input port 1 (9) is input, output ports 5 (24), 6 (25), 7 (26), and 8 (27) output signals with equal amplitude and 0° phase difference. When input port 2 (10) is input, output ports 5 (24), 6 (25), 7 (26), and 8 (27) output signals with different phase differences. (25), the signal amplitudes output by output port seven (26), and output port eight (27) are equal, and they have a phase difference of 180° in sequence; when input port three (11) is input, the signal amplitudes output by output port five (24), output port six (25), output port seven (26), and output port eight (27) are equal, and they have a phase difference of 90° in sequence; when input port four (12) is input, the signal amplitudes output by output port five (24), output port six (25), output port seven (26), and output port eight (27) are equal, and they have a phase difference of -90° in sequence.

3. The dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator according to claim 1, characterized in that, The first dual-frequency filter 180° coupler (2) and the second dual-frequency filter 180° coupler (3) have the same structure and the same size. The first dual-frequency filter 180° coupler (2) includes a first SLR (28), a second SLR (29), a third SLR (30), and a fourth SLR (31). The first SLR (28) and the second SLR (29) have the same size and the same placement direction. The third SLR (30) and the fourth SLR (31) have the same size and the opposite placement direction. The input port seven (32) is coupled to the first SLR (28) through a microstrip line segment (33). The signal is divided into two parts: one part is coupled to the second SLR (29) through electrical coupling, and then coupled to the microstrip line segment (37) and transmitted to the output port three (36); the other part is transmitted to the third SLR (30) through electromagnetic hybrid coupling, and then coupled to the microstrip line segment (39) and transmitted to the output port ten (38). The input port six (34) is coupled to the fourth SLR (31) via a microstrip line segment (35). The signal is divided into two parts: one part is coupled to the second SLR (29) via electromagnetic hybrid coupling, and then coupled to the microstrip line segment (37) to be transmitted to the output port three (36); the other part is transmitted to the third SLR (30) via magnetic coupling, and then coupled to the microstrip line segment (39) to be transmitted to the output port ten (38). When input port seven (32) is input, the signals output by output port three (36) and output port ten (38) have dual-frequency bandpass filtering characteristics, and the output signals have the same phase and amplitude; when input port six (34) is input, the signals output by output port three (36) and output port ten (38) have dual-frequency bandpass filtering characteristics, the output signals have the same amplitude, and there is a 180° phase difference.

4. The dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator according to claim 1, characterized in that, The first broadband 90° coupler (4) and the second broadband 90° coupler (5) have the same structure and size, and are both four-branch directional couplers. The first broadband 90° coupler (4) includes input port five (40), input port eight (41), output port three (42), output port four (43), a first microstrip transmission line (44), a second microstrip transmission line (46), a third microstrip transmission line (47), a fourth microstrip transmission line (49), a fifth microstrip transmission line (45), a sixth microstrip transmission line (48), a seventh microstrip transmission line (50), an eighth microstrip transmission line (53), a ninth microstrip transmission line (51), and a tenth microstrip transmission line (52). The first microstrip transmission line (44), the second microstrip transmission line (46), the third microstrip transmission line (47), and the fourth microstrip transmission line (49) have the same size. The fifth microstrip transmission line (45) and the sixth microstrip transmission line (48) have the same size. The seventh microstrip transmission line (50) and the eighth microstrip transmission line (52) have the same size. The lines (53) are of the same size, and the ninth microstrip transmission line (51) and the tenth microstrip transmission line (52) are of the same size. The input port five (40) is connected to the output port three (42) in turn through the first microstrip transmission line (44), the fifth microstrip transmission line (45), and the second microstrip transmission line (46); the input port eight (41) is connected to the output port four (43) in turn through the third microstrip transmission line (47), the sixth microstrip transmission line (48), and the fourth microstrip transmission line (49); The ends of a microstrip transmission line (44) and a third microstrip transmission line (47) are connected via a seventh microstrip transmission line (50) and a ninth microstrip transmission line (51), respectively; the ends of a fifth microstrip transmission line (45) and a sixth microstrip transmission line (48) are connected via a ninth microstrip transmission line (51) and a tenth microstrip transmission line (52), respectively; the ends of a second microstrip transmission line (46) and a fourth microstrip transmission line (49) are connected via a tenth microstrip transmission line (52) and an eighth microstrip transmission line (53), respectively. When input port five (40) is input, the signal amplitudes output by output port three (42) and output port four (43) are equal, but the phase of the output signal of output port three (42) leads the phase of output port four (43) by 90°; when input port eight (41) is input, the signal amplitudes output by output port three (42) and output port four (43) are equal, but the phase of the output signal of output port three (42) lags the phase of output port four (43) by 90°.

5. The dual-band 4x4 Butler matrix based on branch loaded resonators according to claim 1, characterized in that, The first broadband 90° phase shifter (6), the second broadband 90° phase shifter (7), and the third broadband 90° phase shifter (8) have the same structure and the same size. The first broadband 90° phase shifter (6) includes an input port nine (54), an output port nine (55), an eleventh microstrip transmission line (56), a twelfth microstrip transmission line (57), a thirteenth microstrip transmission line (58), a first microstrip line (59) with a short-circuited terminal, a second microstrip line (60), a first grounding metal through hole (61), and a second grounding metal through hole (62). The structure is symmetrical from left to right. The input port nine (54) is connected to the output port nine (55) in sequence through the eleventh microstrip transmission line (56), the twelfth microstrip transmission line (57), and the thirteenth microstrip transmission line (58); a first microstrip line (59) with a short-circuited termination is connected in parallel between the input port and the eleventh microstrip transmission line (56), and the short-circuiting termination is achieved through the grounded first grounding metal via (61); a second microstrip line (60) with a short-circuited termination is connected in parallel between the output port and the thirteenth microstrip transmission line (58), and the short-circuiting termination is achieved through the grounded second grounding metal via (62).

6. The dual-frequency filtering 4×4 Butler matrix based on a spur-loaded resonator according to claim 1, characterized in that, The width W of the first transmission line (13), the second transmission line (14), the third transmission line (15), the fourth transmission line (16), the fifth transmission line (17), the sixth transmission line (18), the seventh transmission line (19), the eighth transmission line (20), the ninth transmission line (21), the tenth transmission line (22), and the eleventh transmission line (23) is 1.56 mm, which is the width of a 50Ω microstrip line with a center frequency of 15 GHz.

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