A broadband Nolen matrix with flat amplitude and phase between output ports

Abstract

The present invention discloses a broadband Nolen matrix with flat amplitude and phase between output ports, comprising three input ports, three output ports, two open short-circuit line-loaded phase shifting lines, three three-branch directional couplers, and two phase shifting lines. The output phase of the two open short-circuit line-loaded phase shifting lines is determined by the phase difference between the open short-circuit line-loaded phase shifting lines and the phase shifting line. The present invention realizes broadband matching characteristics by adopting a three-branch directional coupler, and then adjusts the flatness of the output amplitude and phase by adjusting the two open short-circuit line-loaded phase shifting lines, thereby realizing the performance of beamforming within a broadband range.

Description

Technical Field

[0001] The invention relates to the field of microwave antennas, and in particular to a broadband Nolen matrix with flat amplitude and phase between output ports. Background Art

[0002] The beamforming network is an important component of the multi-beam antenna array. The main function of the beamforming network is to provide different power and phase distributions on the antenna, so as to achieve the control of the directivity of the beam and form a multi-beam antenna. The Butler matrix is ​​more commonly used in the beamforming network. The Butler matrix has the advantages of convenience, simplicity, and low loss, and has been widely used in beamforming networks. However, in the structural design of the Butler matrix, the complexity of the Butler matrix is ​​increased due to the use of cross junctions. In order to simplify the structure of the Butler matrix, the Blass matrix and Nolen matrix were proposed. The Blass matrix is ​​mainly composed of a coupler, a phase shifter, and a load end, and has the same input and output ports as the Butler matrix. Due to the existence of the terminal load, part of the energy will flow into the load, resulting in the overall efficiency of the Blass matrix being lower than that of the Butler matrix.

[0003] Compared with the Butler matrix, the Nolen matrix reduces the use of cross junctions in structure, making the entire circuit structure simpler. Compared with the Blass matrix, it not only reduces the size of the entire structure, but also reduces energy loss. However, the couplers are connected by phase-shifting lines, which causes the amplitude and phase difference between the output ports to be non-flat. The output amplitude and output phase difference of the Nolen matrix that have been proposed so far have discrete characteristics and fail to achieve the required amplitude and phase difference in a wide band. There are few studies on the wide-band Nolen matrix, so a Nolen matrix that achieves a flat amplitude and phase difference between the output ports in a wide band is proposed. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention discloses a broadband Nolen matrix with flat amplitude and phase between output ports, comprising a first open short-circuit line loaded phase shift line, a second open short-circuit line loaded phase shift line, a first three-branch directional coupler, a second three-branch directional coupler, a third three-branch directional coupler, a first phase shift line, a second phase shift line, an input port and an output port;

[0005] The first open short-circuit line loaded phase-shift line includes a first open line, a first short-circuit line, a second open line, a second short-circuit line and a 50-ohm transmission line; the second open short-circuit line loaded phase-shift line includes a third open line, a third short-circuit line, a fourth open line, a fourth short-circuit line and a 50-ohm meandering line;

[0006] The first three-branch directional coupler includes a first low-impedance horizontal microstrip line, a second low-impedance horizontal microstrip line, a first high-impedance vertical microstrip line, a second high-impedance vertical microstrip line and a first low-impedance vertical microstrip line; the second three-branch directional coupler and the third three-branch directional coupler have the same structure; the second three-branch directional coupler and the first three-branch directional coupler have different structures; the second three-branch directional coupler includes a third low-impedance horizontal microstrip line, a fourth low-impedance horizontal microstrip line, a third high-impedance vertical microstrip line, a fourth high-impedance vertical microstrip line and a second low-impedance vertical microstrip line;

[0007] The input ports include a first input port, a second input port, and a third input port; the output ports include a first output port, a second output port, and a third output port;

[0008] The first input port is connected to one end of the first phase-shifting line; the other end of the first phase-shifting line is connected to the upper left port of the first three-branch directional coupler; the upper right port of the first three-branch directional coupler is connected to one end of the first open short-circuit line loaded phase-shifting line; the other end of the first open short-circuit line loaded phase-shifting line is connected to the first output port;

[0009] The second input port is connected to the upper left port of the second three-branch directional coupler; the upper right port of the second three-branch directional coupler is connected to the lower left port of the first three-branch directional coupler; the lower right port of the first three-branch directional coupler is connected to the left end of the second phase-shifting line; the right end of the second phase-shifting line is connected to the upper left port of the third three-branch directional coupler; the upper right port of the third three-branch directional coupler is connected to the second output port;

[0010] The third input port is connected to the lower left port of the second three-branch directional coupler; the lower right port of the second three-branch directional coupler is connected to the left end of the second open short-circuit line loaded phase-shift line; the right end of the second open short-circuit line loaded phase-shift line is connected to the lower left port of the third three-branch directional coupler; the lower right port of the third three-branch directional coupler is connected to the third output port.

[0011] The impedance of the first phase-shifting line and the second phase-shifting line is 50 ohms; the first open line and the second open line have the same size; the first short-circuit line and the second short-circuit line have the same size; the first open line and the first short-circuit line have the same electrical length and different impedance; the third open line and the fourth open line have the same size; the third short-circuit line and the fourth short-circuit line have the same size; the third open line and the third short-circuit line have the same impedance and different electrical length.

[0012] Wideband matching is performed by using a first three-branch directional coupler, a second three-branch directional coupler, and a third three-branch directional coupler; and a flat amplitude difference and phase difference between output ports are obtained by adjusting the phase relationship between the first open short-circuit line loaded phase shift line, the second open short-circuit line loaded phase shift line, and the second phase shift line.

[0013] When the first input port is excited, the phase difference between the first output port and the second output port, and the phase difference between the second output port and the third output port are both -90°; when the second input port is excited, the phase difference between the first output port and the second output port, and the phase difference between the second output port and the third output port are both 150°; when the third input port is excited, the phase difference between the first output port and the second output port, and the phase difference between the second output port and the third output port are both 30°.

[0014] The phase difference between the first open short-circuit line loaded phase-shift line and the second phase-shift line is 180°; the phase difference between the second open short-circuit line loaded phase-shift line and the second phase-shift line is 90°.

[0015] The coupling degree of the first three-branch directional coupler is 1.76 dB, and the coupling degree of the second three-branch directional coupler is 3 dB.

[0016] The impedances of the first open line and the first short line are both greater than 50 ohms; the electrical length of the third open line is less than 45°; and the electrical length of the third short line is greater than 45°.

[0017] Due to the adoption of the above technical scheme, the present invention provides a broadband Nolen matrix with flat amplitude and phase between output ports. The structure realizes a broadband impedance-matched Nolen matrix by adopting a three-branch directional coupler, and realizes a flat amplitude difference and phase difference between output ports by adopting an open short-circuit line to load a phase-shifting line. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the structure of a broadband Nolen matrix with flat amplitude and phase between output ports of the present invention;

[0020] Figure 2It is a schematic structural diagram of a first three-branch directional coupler and a second three-branch directional coupler in a broadband Nolen matrix with flat amplitude and phase between output ports of the present invention;

[0021] Figure 3 It is a schematic structural diagram of a first open short-circuit line loaded phase-shifting line and a second open short-circuit line loaded phase-shifting line in a broadband Nolen matrix with flat amplitude and phase between output ports of the present invention;

[0022] Figure 4 It is a diagram of impedance matching results of each input and output port of a broadband Nolen matrix with flat amplitude and phase between output ports of the present invention;

[0023] Figure 5 It is a result diagram of the isolation curve between the ports of the broadband Nolen matrix with flat amplitude and phase between the output ports of the present invention;

[0024] 6 is a diagram showing the amplitude difference between output ports of a broadband Nolen matrix with flat amplitude and phase between output ports of the present invention;

[0025] Figure 7 It is a result diagram of the phase difference between the output ports of the broadband Nolen matrix with flat amplitude and phase between the output ports of the present invention;

[0026] In the figure: 1. The first open short-circuit line loaded with a phase-shifting line, 11. The first open line, 12. The first short-circuit line, 13. The second open line, 14. The second short-circuit line, 15. The 50-ohm transmission line 2. The second open short-circuit line loaded with a phase-shifting line, 21. The third open line, 22. The third short-circuit line, 23. The fourth open line, 24. The fourth short-circuit line, 25. The 50-ohm meandering line 3. The first three-branch directional coupler, 31. The first low-impedance horizontal microstrip line, 32. The second low-impedance horizontal microstrip line, 33. The first high-impedance vertical microstrip line, 34. The second high-impedance vertical microstrip line, 35. The first low-impedance vertical microstrip line, 4. The second three-branch directional coupler, 41 , a third low-impedance horizontal microstrip line, 42, a fourth low-impedance horizontal microstrip line, 43, a third high-impedance vertical microstrip line, 44, a fourth high-impedance vertical microstrip line, 45, a second low-impedance vertical microstrip line, 5, a third three-branch directional coupler, 51, a fourth low-impedance horizontal microstrip line, 52, a fifth low-impedance horizontal microstrip line, 53, a fourth high-impedance vertical microstrip line, 54, a fifth high-impedance vertical microstrip line, 55, a third low-impedance vertical microstrip line, 6, a first phase-shift line, 7, a second phase-shift line, 81, input port 1, 82, input port 2, 83, input port 3, 91, output port 1, 92, output port 2, 93, output port 3. DETAILED DESCRIPTION

[0027] In order to make the purpose of the invention, implementation method and implementation function of the present invention more clear, the present invention is further described below in conjunction with specific implementation methods and drawings.

[0028] The technical indicators used in this embodiment are as follows:

[0029] Frequency range: 3GHz~8GHz

[0030] Return loss:>15dB;

[0031] Isolation:>15dB;

[0032] Output port amplitude: -4.77±1dB

[0033] Output port phase difference when port 1 is input: -90°±5°;

[0034] Output port phase difference when port 2 is input: 150°±5°;

[0035] Output port phase difference when port 3 is input: 30°±5°.

[0036] like Figure 1-3 As shown, a broadband Nolen matrix beamforming network with flat amplitude and phase differences between output ports includes three input ports, three output ports, three three-branch directional couplers, two open-short circuit loaded phase shifters, and two phase shift lines;

[0037] The first open short-circuit line loaded phase-shifting line 1 comprises a first open line 11, a first short-circuit line 12, a second open line 13, a second short-circuit line 14 and a 50-ohm transmission line 15; the second open short-circuit line loaded phase-shifting line 2 comprises a third open line 21, a third short-circuit line 22, a fourth open line 23, a fourth short-circuit line 24 and a 50-ohm meandering line 25;

[0038] The first three-branch directional coupler 3 includes a first low-impedance horizontal microstrip line 31, a second low-impedance horizontal microstrip line 32, a first high-impedance vertical microstrip line 33, a second high-impedance vertical microstrip line 34 and a first low-impedance vertical microstrip line 35; the second three-branch directional coupler 4 and the third three-branch directional coupler 5 have the same structure; the second three-branch directional coupler 4 and the first three-branch directional coupler 3 have different structures; the second three-branch directional coupler 4 includes a third low-impedance horizontal microstrip line 41, a fourth low-impedance horizontal microstrip line 42, a third high-impedance vertical microstrip line 43, a fourth high-impedance vertical microstrip line 44 and a second low-impedance vertical microstrip line 45;

[0039] The input port 8 includes a first input port 81, a second input port 82, and a third input port 83; the output port 9 includes a first output port 91, a second output port 92, and a third output port 93;

[0040] The first input port 81 is connected to the left end of the first phase-shifting line 6; the right end of the first phase-shifting line 6 is connected to the upper left port of the first three-branch directional coupler 3; the upper right port of the first three-branch directional coupler 3 is connected to the left end of the first open short-circuit line loaded phase-shifting line 1; the right end of the first open short-circuit line loaded phase-shifting line 1 is connected to the first output port 91;

[0041] The second input port 82 is connected to the upper left port of the second three-branch directional coupler 4; the upper right port of the second three-branch directional coupler 4 is connected to the lower left port of the first three-branch directional coupler 3; the lower right port of the first three-branch directional coupler 3 is connected to the left end of the second phase shift line 7; the right end of the second phase shift line 7 is connected to the upper left port of the third three-branch directional coupler 5; the upper right port of the third three-branch directional coupler 5 is connected to the second output port 92;

[0042] The third input port 83 is connected to the lower left port of the second three-branch directional coupler 4; the lower right port of the second three-branch directional coupler 4 is connected to the left end of the second open short-circuit line loaded phase-shifting line 2; the right end of the second open short-circuit line loaded phase-shifting line 2 is connected to the lower left port of the third three-branch directional coupler 5; the lower right port of the third three-branch directional coupler 5 is connected to the third output port 93;

[0043] The impedance of the first phase-shifting line 6 and the second phase-shifting line 7 is 50 ohms; the first open line 11 and the second open line 13 have the same size; the first short-circuit line 12 and the second short-circuit line 14 have the same size; the first open line 11 and the first short-circuit line 12 have the same electrical length and different impedance; the third open line 21 and the fourth open line 23 have the same size; the third short-circuit line 22 and the fourth short-circuit line 24 have the same size; the third open line 21 and the third short-circuit line 22 have the same impedance and different electrical length;

[0044] By adopting the first three-branch directional coupler 3, the second three-branch directional coupler 4, and the third three-branch directional coupler 5, a wide-band matching characteristic can be achieved; by adjusting the phase relationship between the first open short-circuit line loaded phase shift line 1, the second open short-circuit line loaded phase shift line 2, and the second phase shift line 7, a flat amplitude difference and phase difference between the output ports can be obtained;

[0045] When the first input port 81 is excited, the phase difference between the first output port 91 and the second output port 92, and the phase difference between the second output port 92 and the third output port 93 are both -90°; when the second input port 82 is excited, the phase difference between the first output port 91 and the second output port 92, and the phase difference between the second output port 92 and the third output port 93 are both 150°; when the third input port 83 is excited, the phase difference between the first output port 91 and the second output port 92, and the phase difference between the second output port 92 and the third output port 93 are both 30°.

[0046] The phase difference between the first open short-circuit line loaded phase shift line 1 and the second phase shift line 7 is 180°; the phase difference between the second open short-circuit line loaded phase shift line 2 and the second phase shift line 7 is 90°;

[0047] The coupling degree of the first three-branch directional coupler 3 is 1.76 dB, and the coupling degree of the second three-branch directional coupler 4 is 3 dB;

[0048] The impedances of the first open line 11 and the first short line 12 are both greater than 50 ohms; the electrical length of the third open line 21 is less than 45°; and the electrical length of the third short line 22 is greater than 45°.

[0049] Specific embodiments of the present invention are described below.

[0050] In a specific implementation example of the present invention, the coupling ratio of the first three-branch directional coupler is C1=2 / 3, and the coupling ratio of the second three-branch directional coupler and the third three-branch directional coupler is C2=1 / 2. The amplitudes between the output ports of the Nolen matrix are equal, and the phase differences between the output ports when each port is input are equal, which can be obtained.

[0051]

[0052] θ4(f)-θ3(f)=π

[0053] In this embodiment, θ3(f0)=π,θ4(f0)=2π。 Among them, θ2(f) is the electrical length of the 50 ohm meandering line in the second open short circuit loaded phase shift line that changes with frequency, θ3(f) is the electrical length of the first phase shift line that changes with frequency, θ4(f) is the electrical length of the 50 ohm transmission line in the first open short circuit loaded phase shift line that changes with frequency, θ2(f0) is the electrical length of the second open short circuit loaded phase shift line at the center frequency, θ3(f0) is the electrical length of the second phase shift line at the center frequency, θ4(f0) is the electrical length of the first open short circuit loaded phase shift line at the center frequency.

[0054] For the first short-circuit line loaded with phase-shifting line, the expression of unknown parameters can be obtained as follows:

[0055]

[0056] where θ 11 (f) is the electrical length of the 50 ohm transmission line in the first open short-circuit loaded phase-shift line with respect to frequency variation, θ 12 (f) is the electrical length of the first open line in the first open short-circuit loaded phase-shift line with respect to frequency change, θ 13 (f) is the electrical length of the first short-circuit line in the first open short-circuit line loading phase shift line with respect to frequency change, Z 11 The impedance value of the 50 ohm transmission line in the first short-circuit loading phase-shift line, Z 12 The impedance value of the first open line in the phase-shift line is loaded by the first open short-circuit line, Z 13 is the impedance value of the first short-circuit line in the first open short-circuit line loaded phase-shift line, Z0 is the characteristic impedance of 50 ohms, a1 is the port matching value of the first open short-circuit line loaded phase-shift line, and b1 is the port output phase difference of the first open short-circuit line loaded phase-shift line.

[0057] For the second open short-circuit line loaded with phase-shifting line, the expression of the unknown parameters can be obtained as follows:

[0058]

[0059] where θ 21 (f) is the electrical length of the 50 ohm meandering line in the second short-circuit loaded phase-shifting line with respect to frequency variation, θ 22 (f) is the electrical length of the third open line in the second open short-circuit line loaded phase shift line with respect to frequency change, θ 23 (f) is the electrical length of the third short-circuit line in the second open short-circuit line loading phase-shift line with respect to frequency variation, Z 21 The impedance value of the 50 ohm meandering line in the second short-circuit line loading phase shift line, Z 22 The impedance value of the third open line in the phase-shifting line is loaded on the second open short-circuit line, Z 23 is the impedance value of the third short-circuit line in the second open short-circuit line loaded phase-shift line, Z0 is the characteristic impedance of 50 ohms, a2 is the port matching value of the second open short-circuit line loaded phase-shift line, and b2 is the port output phase difference of the second open short-circuit line loaded phase-shift line.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A broadband Nolen matrix with flat amplitude and phase between output ports, characterized in that include: A first open short-circuit line loaded phase-shift line (1), a second open short-circuit line loaded phase-shift line (2), a first three-branch directional coupler (3), a second three-branch directional coupler (4), a third three-branch directional coupler (5), a first phase-shift line (6), a second phase-shift line (7), an input port (8) and an output port (9); The first open short-circuit line loaded phase-shift line (1) comprises a first open line (11), a first short-circuit line (12), a second open line (13), a second short-circuit line (14) and a 50-ohm transmission line (15); the second open short-circuit line loaded phase-shift line (2) comprises a third open line (21), a third short-circuit line (22), a fourth open line (23), a fourth short-circuit line (24) and a 50-ohm meandering line (25); The first three-branch directional coupler (3) comprises a first low-impedance horizontal microstrip line (31), a second low-impedance horizontal microstrip line (32), a first high-impedance vertical microstrip line (33), a second high-impedance vertical microstrip line (34) and a first low-impedance vertical microstrip line (35); the second three-branch directional coupler (4) and the third three-branch directional coupler (5) have the same structure; the second three-branch directional coupler (4) and the first three-branch directional coupler (3) have different structures; the second three-branch directional coupler (4) comprises a third low-impedance horizontal microstrip line (41), a fourth low-impedance horizontal microstrip line (42), a third high-impedance vertical microstrip line (43), a fourth high-impedance vertical microstrip line (44) and a second low-impedance vertical microstrip line (45); The input port (8) includes a first input port (81), a second input port (82), and a third input port (83); the output port (9) includes a first output port (91), a second output port (92), and a third output port (93); The first input port (81) is connected to one end of a first phase-shifting line (6); the other end of the first phase-shifting line (6) is connected to the upper left port of a first three-branch directional coupler (3); the upper right port of the first three-branch directional coupler (3) is connected to one end of a first open short-circuit line loaded phase-shifting line (1); the other end of the first open short-circuit line loaded phase-shifting line (1) is connected to a first output port (91); The second input port (82) is connected to the upper left port of the second three-branch directional coupler (4); the upper right port of the second three-branch directional coupler (4) is connected to the lower left port of the first three-branch directional coupler (3); the lower right port of the first three-branch directional coupler (3) is connected to the left end of the second phase shift line (7); the right end of the second phase shift line (7) is connected to the upper left port of the third three-branch directional coupler (5); the upper right port of the third three-branch directional coupler (5) is connected to the second output port (92); The third input port (83) is connected to the lower left port of the second three-branch directional coupler (4); the lower right port of the second three-branch directional coupler (4) is connected to the left end of the second open short-circuit line loaded phase-shift line (2); the right end of the second open short-circuit line loaded phase-shift line (2) is connected to the lower left port of the third three-branch directional coupler (5); and the lower right port of the third three-branch directional coupler (5) is connected to the third output port (93).

2. The broadband Nolen matrix with flat amplitude and phase between output ports according to claim 1, characterized in that: The impedance of the first phase-shifting line (6) and the second phase-shifting line (7) is 50 ohms; the first open line (11) and the second open line (13) have the same size; the first short-circuit line (12) and the second short-circuit line (14) have the same size; the first open line (11) and the first short-circuit line (12) have the same electrical length and different impedances; the third open line (21) and the fourth open line (23) have the same size; the third short-circuit line (22) and the fourth short-circuit line (24) have the same size; the third open line (21) and the third short-circuit line (22) have the same impedance and different electrical lengths.

3. The broadband Nolen matrix with flat amplitude and phase between output ports according to claim 1, characterized in that: A first three-branch directional coupler (3), a second three-branch directional coupler (4), and a third three-branch directional coupler (5) are used to perform wideband matching; and a flat amplitude difference and phase difference between output ports are obtained by adjusting the phase relationship between the first short-circuit-loaded phase-shift line (1), the second short-circuit-loaded phase-shift line (2), and the second phase-shift line (7).

4. The broadband Nolen matrix with flat amplitude and phase between output ports according to claim 1, characterized in that: When the first input port (81) is excited, the phase difference between the first output port (91) and the second output port (92), and the phase difference between the second output port (92) and the third output port (93) are both -90°; when the second input port (82) is excited, the phase difference between the first output port (91) and the second output port (92), and the phase difference between the second output port (92) and the third output port (93) are both 150°; when the third input port (83) is excited, the phase difference between the first output port (91) and the second output port (92), and the phase difference between the second output port (92) and the third output port (93) are both 30°.

5. The broadband Nolen matrix with flat amplitude and phase between output ports according to claim 1, characterized in that: The phase difference between the first short-circuit-connected phase-shifting line (1) and the second phase-shifting line (7) is 180°; the phase difference between the second short-circuit-connected phase-shifting line (2) and the second phase-shifting line (7) is 90°.

6. The broadband Nolen matrix with flat amplitude and phase between output ports according to claim 1, characterized in that: The coupling degree of the first three-branch directional coupler (3) is 1.76 dB, and the coupling degree of the second three-branch directional coupler (4) is 3 dB.

7. The broadband Nolen matrix with flat amplitude and phase between output ports according to claim 1, characterized in that: The impedances of the first open line (11) and the first short line (12) are both greater than 50 ohms; the electrical length of the third open line (21) is less than 45°; and the electrical length of the third short line (22) is greater than 45°.

Images