Branch-line directional coupler and coupler

Abstract

The utility model relates to a branch line directional coupling circuit and coupler, including by first directional waveguide transmission line, second directional waveguide transmission line, third directional waveguide transmission line, fourth directional waveguide transmission line, fifth directional waveguide transmission line, sixth directional waveguide transmission line, seventh directional waveguide transmission line and eighth directional waveguide transmission line connection constitute mouth shape; The directional waveguide transmission line at the corner is adjustable directional waveguide transmission line of width, the one end of first directional waveguide transmission line is not connected with other directional waveguide transmission line and is configured as input port, the one end of third directional waveguide transmission line is not connected with other directional waveguide transmission line and is configured as first output port, the one end of eighth directional waveguide transmission line is not connected with other directional waveguide transmission line and is configured as second output port, the one end of sixth directional waveguide transmission line is not connected with other directional waveguide transmission line and is configured as isolation port.

Description

Technical Field

[0001] This disclosure relates to the field of microwave and radio frequency circuit technology, and in particular to a branch-line directional coupling circuit and coupler. Background Technology

[0002] A branch-line directional coupler is a four-port network consisting of a square ring with a perimeter equal to one waveguide wavelength. It distributes the input signal to the coupling and through ports in a specific ratio while ensuring signal suppression at the isolation ports. In a traditional branch-line directional coupler, the power input at port 1 is equally distributed to ports 2 and 3, with the two output ports 90 degrees out of phase. This type of directional coupler is called a 3dB bridge, where the series arm impedance of the 3dB bridge is... The series arm is 50 ohms, and the parallel arm is 50 ohms. The output power ratio is 1:1. The voltage coupling coefficient of ports 2 and 3 is the impedance ratio of the series arm and the parallel arm. It cannot meet the power output requirements of different power ratios in relevant scenarios. Utility Model Content

[0003] The purpose of this invention is to provide a branch-line directional coupling circuit and coupler, which aims to solve the technical problem that traditional branch-line directional couplers cannot meet the power output requirements of different power ratios in relevant scenarios.

[0004] To achieve the above objectives, a first aspect of this disclosure provides a branch-line directional coupling circuit, the branch-line directional coupling circuit comprising:

[0005] First directional waveguide transmission line, second directional waveguide transmission line, third directional waveguide transmission line, fourth directional waveguide transmission line, fifth directional waveguide transmission line, sixth directional waveguide transmission line, seventh directional waveguide transmission line and eighth directional waveguide transmission line;

[0006] The first, second, third, fourth, fifth, sixth, seventh, and eighth directional waveguide transmission lines are connected to form a U-shape. The first, third, sixth, and eighth directional waveguide transmission lines are adjustable-width directional waveguide transmission lines and are respectively located at one corner of the U-shape. The second, fourth, fifth, and seventh directional waveguide transmission lines are located on the four sides of the U-shape.

[0007] Wherein, the end of the first directional waveguide transmission line not connected to any other directional waveguide transmission line is configured as the input port of the branch-line directional coupler; the end of the third directional waveguide transmission line not connected to any other directional waveguide transmission line is configured as the first output port of the branch-line directional coupler; the end of the eighth directional waveguide transmission line not connected to any other directional waveguide transmission line is configured as the second output port of the branch-line directional coupler; and the end of the sixth directional waveguide transmission line not connected to any other directional waveguide transmission line is configured as the isolation port of the branch-line directional coupler.

[0008] In one possible implementation, the directional waveguide transmission lines on the diagonal of the U-shape are directional waveguide transmission lines of the same specification, the directional waveguide transmission lines on adjacent corners of the U-shape are directional waveguide transmission lines of different specifications, the symmetrical sides of the U-shape are directional waveguide transmission lines of the same specification, and the adjacent sides of the U-shape are directional waveguide transmission lines of different specifications.

[0009] In one possible implementation, the first directional waveguide transmission line is configured as the first port of the input port of the branch-line directional coupler, and the first distance between the first directional waveguide transmission line and the second port of the third directional waveguide transmission line, which is configured as the first output port of the branch-line directional coupler, is one-quarter of the waveguide wavelength.

[0010] The first directional waveguide transmission line is configured as the first port of the input port of the branch line directional coupler, and the second spacing between the sixth directional waveguide transmission line and the port of the sixth directional waveguide transmission line that is not connected to any other directional waveguide transmission line is one-quarter of the waveguide wavelength.

[0011] In one possible implementation, the impedance of each port of the branch-line directional coupling circuit is 50 ohms, and the impedance of the series arm is... Ohm, the impedance of the parallel arm is Ohm, the length of each arm is one-quarter of the waveguide wavelength.

[0012] In one possible implementation, the port impedance of the branch-line directional coupling circuit is 50 ohms, and the series arm impedance is... Ohm, the impedance of the parallel arm is Ohm, the length of each arm is one-quarter of the waveguide wavelength.

[0013] In one possible implementation, the directional waveguide transmission line is any of the following: microstrip line, stripline, or coaxial line.

[0014] A second aspect of this disclosure provides a branch-line directional coupler, comprising: the branch-line directional coupling circuit described in any one aspect of the first aspect.

[0015] This invention provides a branch-line directional coupling circuit and coupler. Compared with the prior art, it has the following advantages:

[0016] By setting adjustable-bandwidth directional waveguide transmission lines and rationally configuring the bandwidth of the directional waveguide transmission lines at the four corners of the U-shaped configuration, the power from the two output ports can be output non-equally, achieving power outputs with different power ratios. This improves the adaptability, ease of use, and practical flexibility of the branch-line directional coupling circuit.

[0017] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a circuit diagram of a branch line directional coupling circuit shown in the embodiment of the specification.

[0020] Figure 2 This is a simulation diagram of a 4dB branch-line directional coupling circuit as shown in the embodiment of the specification.

[0021] Figure 3 This is a simulation diagram of a 6dB branch-line directional coupling circuit as shown in the embodiment of the specification. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0024] In view of this, this disclosure provides a branch-line directional coupling circuit, see [link to relevant documentation]. Figure 1 As shown, the branch line directional coupling circuit includes:

[0025] First directional waveguide transmission line 10, second directional waveguide transmission line 20, third directional waveguide transmission line 30, fourth directional waveguide transmission line 40, fifth directional waveguide transmission line 50, sixth directional waveguide transmission line 60, seventh directional waveguide transmission line 70 and eighth directional waveguide transmission line 80;

[0026] The first directional waveguide transmission line 10, the second directional waveguide transmission line 20, the third directional waveguide transmission line 30, the fourth directional waveguide transmission line 40, the fifth directional waveguide transmission line 50, the sixth directional waveguide transmission line 60, the seventh directional waveguide transmission line 70, and the eighth directional waveguide transmission line 80 are connected to form a U-shape. The first directional waveguide transmission line 10, the third directional waveguide transmission line 30, the sixth directional waveguide transmission line 60, and the eighth directional waveguide transmission line 80 are directional waveguide transmission lines with adjustable widths and are respectively located at one corner of the U-shape. The second directional waveguide transmission line 20, the fourth directional waveguide transmission line 40, the fifth directional waveguide transmission line 50, and the seventh directional waveguide transmission line 70 are located on the four sides of the U-shape.

[0027] The main transmission line is a 1-2 loop consisting of the first directional waveguide transmission line 10, the second directional waveguide transmission line 20, and the third directional waveguide transmission line 30. The auxiliary transmission line is a 4-3 loop consisting of the sixth directional waveguide transmission line 60, the seventh directional waveguide transmission line 70, and the eighth directional waveguide transmission line 80. The spacing between 1-2 and 1-4 is one-quarter of the waveguide wavelength, and the characteristic impedance of each port is 50 ohms. The radio frequency signal is input through port 1 and output through ports 2 and 3, with a 90-degree phase difference between ports 2 and 3. Ports 1 and 4 are isolated from each other. The branch-line directional coupling circuit can be considered as consisting of four transmission arms: two horizontal series arms and two vertical parallel arms.

[0028] In this embodiment, a closed rectangular loop is formed by eight directional waveguide transmission lines, which are divided into two types: adjustable-width directional waveguide transmission lines located at the four corners of the rectangle, which achieve impedance transformation and phase control by adjusting their width; and transmission lines connecting the corner directional waveguide transmission lines, which form the main transmission path (loop 1-2) and the auxiliary coupling path (loop 4-3).

[0029] Wherein, the end of the first directional waveguide transmission line 10 that is not connected to other directional waveguide transmission lines is configured as the input port of the branch line directional coupler; the end of the third directional waveguide transmission line 30 that is not connected to other directional waveguide transmission lines is configured as the first output port of the branch line directional coupler; the end of the eighth directional waveguide transmission line 80 that is not connected to other directional waveguide transmission lines is configured as the second output port of the branch line directional coupler; and the end of the sixth directional waveguide transmission line 60 that is not connected to other directional waveguide transmission lines is configured as the isolation port of the branch line directional coupler.

[0030] In this embodiment, input port 1 is the open end of the first directional waveguide transmission line 1010, connected to a signal source (such as an RF generator). Straight-through output port 2 is the open end of the third directional waveguide transmission line 3030, outputting the main path signal. Coupled output port 3 is the open end of the eighth directional waveguide transmission line 80, outputting a coupled signal with a 90° phase difference. Isolation port 4 is the open end of the sixth directional waveguide transmission line 60, with no signal output.

[0031] The vertical spacing between arms 1-2 and 1-4 is λg / 4 (waveguide wavelength) to ensure phase difference and isolation characteristics. All transmission line physical lengths are integer multiples of λg / 2 to avoid interference from reflected wave superposition.

[0032] In this embodiment of the disclosure, the input signal enters port 10 from port 1, in the form of TE. 10 The dominant mode (rectangular waveguide mode) propagates along the +z direction to port 20. At the junction of ports 20 and 30, some energy is coupled to port 30 through continuous boundary conditions and is finally output from port 2. During propagation along the main path (10→20), TE 10 The electric field (E-field) of the mode forms an edge field at the narrow side of the waveguide (perpendicular to the propagation direction). This edge field penetrates to an auxiliary path (sixth directional waveguide transmission line 60) parallel to the main path and spaced at a distance of λg / 4 (one-quarter of the waveguide wavelength). The auxiliary path signal originates from 60, passes sequentially through the seventh directional waveguide transmission line 70 and the eighth directional waveguide transmission line 80, and is finally output from port 3. The physical length of the auxiliary path (60→70→80) is λg / 4 longer than that of the main path (10→20→30), causing the phase of the output signal at port 3 to differ from that of the main path signal by 90°.

[0033] The above technical solution, by setting an adjustable broadband directional waveguide transmission line and rationally setting the bandwidth of the directional waveguide transmission lines at the four corners of the U-shaped configuration, allows the power from the two output ports to be output non-equally, achieving power output with different power ratios. This improves the adaptability, ease of use, and practical flexibility of the branch-line directional coupling circuit.

[0034] In one possible implementation, the directional waveguide transmission lines on the diagonal of the U-shape are directional waveguide transmission lines of the same specification, the directional waveguide transmission lines on adjacent corners of the U-shape are directional waveguide transmission lines of different specifications, the symmetrical sides of the U-shape are directional waveguide transmission lines of the same specification, and the adjacent sides of the U-shape are directional waveguide transmission lines of different specifications.

[0035] In this embodiment of the disclosure, the diagonal transmission lines are transmission lines with the same bandwidth and length, and the diagonal transmission lines (such as 10-30 and 60-80) need to transmit the same mode (TE). 10 The signal must be of the same width (w) to ensure phase consistency and form a symmetrical coupling path. The characteristic impedance must be consistent (e.g., 50Ω) to avoid reflection. The characteristic impedance must be the same height (h) to maintain TE. 10 The cutoff frequency and field distribution of the mode. The length (L) can be designed according to phase requirements (e.g., the main path length is Lmain, and the auxiliary path length is Lmain+λg / 4). The symmetrical design ensures that the propagation constants of the diagonal transmission lines are the same, and the signal phase delay is determined only by the length, thereby precisely controlling the phase output of port 3.

[0036] In this embodiment, adjacent corner transmission lines are transmission lines with different bandwidths and lengths (impedance transformation and coupling control). Adjacent corner transmission lines (such as 20-60 and 70-30) need to achieve impedance matching and coupling strength adjustment while suppressing the output of port 4. TE is adjusted by changing the waveguide height (h). 10 The field distribution of the mode controls the coupling strength of the edge field. The length of the angular transmission line must be an odd multiple of λg / 8 to compensate for phase and enhance coupling. The gradient structure reduces reflection and improves coupling efficiency. The height variation adjusts the edge field penetration depth, thereby controlling the output power of port 3.

[0037] In this embodiment, the symmetrical edge transmission lines are transmission lines with the same bandwidth and length, ensuring phase consistency. The symmetrical edge lines (such as 10-20 and 70-80) must guarantee the phase consistency of signal propagation to avoid introducing additional phase errors due to path differences. The width, height, and length can be exactly the same to ensure a consistent propagation constant β. Low-loss media (such as gold-plated copper) or air waveguides are used to reduce attenuation. The symmetrical design ensures that the phase delay difference between the main path and the auxiliary path is determined only by the difference in diagonal length, thereby precisely achieving a 90° phase difference.

[0038] Adjacent edge transmission lines are transmission lines with different bandwidths and lengths to achieve mode isolation and directivity enhancement. Adjacent edge lines (such as 20-70 and 60-30) need to achieve mode isolation to prevent TE (transmission interference). 10 The mode propagates along a non-coupled path, simultaneously enhancing its directionality. Higher-order modes (such as TE) are excited by abruptly changing the width. 20Higher-order modes are attenuated during subsequent transmission. A height step is placed at the junction to utilize field discontinuities to reflect non-target modes. Higher-order modes cannot propagate due to waveguide size limitations; only TE modes are propagated. 10 The mode passes through, thereby suppressing spurious output at port 4. By selecting the mode, the signal is made to propagate only along the target path (such as 10→20→30 and 60→70→80), improving the coupling directionality.

[0039] In one possible implementation, the first directional waveguide transmission line 10 is configured as the first port of the input port of the branch line directional coupler, and the first distance between the first directional waveguide transmission line 30 and the second port of the first output port of the branch line directional coupler is one-quarter of the waveguide wavelength.

[0040] The first directional waveguide transmission line 10 is configured as the first port of the input port of the branch line directional coupler, and the second distance between it and the port of the sixth directional waveguide transmission line 60 that is not connected to other directional waveguide transmission lines is one-quarter of the waveguide wavelength.

[0041] In this embodiment of the disclosure, when the signal propagates from port 1 to port 2, it travels a path length of λg / 4, introducing a 90° phase delay (βL). 12 =π / 2, β = 2π / λg is the propagation constant). If the output signal of port 2 needs to be in phase with that of port 1, an additional 270° phase delay (i.e., 3λg / 4 path) needs to be introduced through a subsequent coupling path (such as port 1 → port 3) to achieve a 90° phase difference at port 3 (270° - 0° = 90°).

[0042] When port 6 is an open circuit, the signal propagates from port 1 to port 6 and is completely reflected (reflection coefficient Γ = +1). The reflected wave and the incident wave superimpose at port 1, forming a standing wave field. By adjusting the position of port 6 (λg / 4), the reflected wave can be made to be out of phase with the directly coupled wave at port 3 (the coupling port), thereby canceling the output of port 4 (improved isolation).

[0043] In one possible implementation, the impedance of each port of the branch-line directional coupling circuit is 50 ohms, and the impedance of the series arm is... Ohm, the impedance of the parallel arm is Ohm, the length of each arm is one-quarter of the waveguide wavelength.

[0044] In this embodiment of the disclosure, the first directional waveguide transmission line 10 may be a stripline with bandwidths of 12.8 mm, 16.1 mm, and 9.0 mm; the second directional waveguide transmission line 20 may be a stripline with a bandwidth of 16.1 mm and a length of 29 mm; the third directional waveguide transmission line 30 may be a stripline with bandwidths of 16.1 mm, 12.8 mm, and 9.0 mm; the fourth directional waveguide transmission line 40 and the fifth directional waveguide transmission line 50 may be striplines with a bandwidth of 9.0 mm and a length of 29 mm; the sixth directional waveguide transmission line 60 may be a stripline with bandwidths of 16.1 mm, 12.8 mm, and 9.0 mm; the seventh directional waveguide transmission line 70 may be a stripline with a bandwidth of 16.1 mm and a length of 29 mm; and the eighth directional waveguide transmission line 80 may be a stripline with bandwidths of 12.8 mm, 16.1 mm, and 9.0 mm.

[0045] In this embodiment of the disclosure, combined with Figure 2 As shown, since the voltage coupling coefficient is determined by the series-parallel arm impedance ratio, if the output power ratio is 2:1, the series-parallel arm impedance ratio is... The power coupling coefficient is 4.77 dB, and the first and second output ports are 90° out of phase. Furthermore, in Figure 2 In the upper left figure, insertion loss is observed in S12 and S13, and isolation is observed in S14, showing good performance. Figure 2 In the upper right figure, the return loss of the four ports is also very good. Figure 2 In the diagram below, it can be seen that the phase difference between ports 2 and 3 is 90 degrees.

[0046] In one possible implementation, the port impedance of the branch-line directional coupling circuit is 50 ohms, and the series arm impedance is... Ohm, the impedance of the parallel arm is Ohm, the length of each arm is one-quarter of the waveguide wavelength.

[0047] In this embodiment of the disclosure, the first directional waveguide transmission line 10 may be a stripline with bandwidths of 12.8 mm, 20.5 mm, and 9.8 mm; the second directional waveguide transmission line 20 may be a stripline with a bandwidth of 20.5 mm and a length of 27.5 mm; the third directional waveguide transmission line 30 may be a stripline with bandwidths of 20.5 mm, 12.8 mm, and 9.8 mm; the fourth directional waveguide transmission line 40 and the fifth directional waveguide transmission line 50 may be striplines with a bandwidth of 9.8 mm and a length of 27.5 mm; the sixth directional waveguide transmission line 60 may be a stripline with bandwidths of 20.5 mm, 12.8 mm, and 9.8 mm; the seventh directional waveguide transmission line 70 may be a stripline with a bandwidth of 20.5 mm and a length of 27.5 mm; and the eighth directional waveguide transmission line 80 may be a stripline with bandwidths of 20.5 mm, 12.8 mm, and 9.8 mm.

[0048] In this embodiment of the disclosure, based on the series-parallel impedance ratio, it can be determined that port 2 outputs 3 / 4 power, port 3 outputs 1 / 4 power, and ports 2 and 3 are 90° out of phase. See also... Figure 3 As shown, in Figure 3 In the upper left figure, insertion loss is shown in S12 and S13, and isolation is shown in S14, with good performance. Figure 3 In the upper right figure, the return loss parameters for all four ports are also very good. Figure 3 In the diagram below, it can be seen that the phase difference between ports 2 and 3 is 90 degrees.

[0049] In one possible implementation, the directional waveguide transmission line is any of the following: microstrip line, stripline, or coaxial line.

[0050] In this embodiment of the disclosure, by changing the bandwidth of the transmission lines at the four corners, various power outputs can be achieved, for example, with output power ratios of 2:1, 3:1, 4:1, and 5:1.

[0051] This disclosure also provides a branch line directional coupler, including: the branch line directional coupling circuit described in any of the foregoing embodiments.

[0052] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various changes, modifications, substitutions and variations can be made to these embodiments, and all such changes, modifications, substitutions and variations fall within the protection scope of the present disclosure.

[0053] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction, and such combinations should also be considered as part of this disclosure. To avoid unnecessary repetition, this disclosure will not further describe the various possible combinations. The technical scope of this application is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A branch-line directional coupling circuit, characterized in that, The branch line directional coupling circuit includes: First directional waveguide transmission line (10), second directional waveguide transmission line (20), third directional waveguide transmission line (30), fourth directional waveguide transmission line (40), fifth directional waveguide transmission line (50), sixth directional waveguide transmission line (60), seventh directional waveguide transmission line (70) and eighth directional waveguide transmission line (80); The first directional waveguide transmission line (10), the second directional waveguide transmission line (20), the third directional waveguide transmission line (30), the fourth directional waveguide transmission line (40), the fifth directional waveguide transmission line (50), the sixth directional waveguide transmission line (60), the seventh directional waveguide transmission line (70), and the eighth directional waveguide transmission line (80) are connected to form a square shape. The first directional waveguide transmission line (10), the third directional waveguide transmission line (30), the sixth directional waveguide transmission line (60), and the eighth directional waveguide transmission line (80) are directional waveguide transmission lines with adjustable width and are respectively located at one corner of the square shape. The second directional waveguide transmission line (20), the fourth directional waveguide transmission line (40), the fifth directional waveguide transmission line (50), and the seventh directional waveguide transmission line (70) are located on the four sides of the square shape. Wherein, the end of the first directional waveguide transmission line (10) not connected to other directional waveguide transmission lines is configured as the input port of the branch line directional coupling circuit, the end of the third directional waveguide transmission line (30) not connected to other directional waveguide transmission lines is configured as the first output port of the branch line directional coupling circuit, the end of the eighth directional waveguide transmission line (80) not connected to other directional waveguide transmission lines is configured as the second output port of the branch line directional coupling circuit, and the end of the sixth directional waveguide transmission line (60) not connected to other directional waveguide transmission lines is configured as the isolation port of the branch line directional coupling circuit.

2. The branch-line directional coupling circuit as described in claim 1, characterized in that, The directional waveguide transmission lines on the diagonal of the "U" shape are of the same specification, the directional waveguide transmission lines on adjacent corners of the "U" shape are of different specifications, the directional waveguide transmission lines on the symmetrical sides of the "U" shape are of the same specification, and the directional waveguide transmission lines on adjacent sides of the "U" shape are of different specifications.

3. The branch-line directional coupling circuit as described in claim 1, characterized in that, The first directional waveguide transmission line (10) is configured as the first port of the input port of the branch line directional coupling circuit, and the first distance between the first port of the third directional waveguide transmission line (30) and the second port of the first output port of the branch line directional coupling circuit is one-quarter of the waveguide wavelength. The first directional waveguide transmission line (10) is configured as the first port of the input port of the branch line directional coupling circuit, and the second distance between the port of the sixth directional waveguide transmission line (60) that is not connected to other directional waveguide transmission lines is one-quarter of the waveguide wavelength.

4. The branch-line directional coupling circuit as described in any one of claims 1-3, characterized in that, The impedance at each port of the branch-line directional coupling circuit is 50 ohms, and the impedance of the series arm is... Ohm, the impedance of the parallel arm is Ohm, the length of each arm is one-quarter of the waveguide wavelength.

5. The branch-line directional coupling circuit as described in any one of claims 1-3, characterized in that, The impedance at each port of the branch-line directional coupling circuit is 50 ohms, and the impedance of the series arm is... Ohm, the impedance of the parallel arm is Ohm, the length of each arm is one-quarter of the waveguide wavelength.

6. The branch-line directional coupling circuit as described in any one of claims 1-3, characterized in that, The directional waveguide transmission line is any of the following: microstrip line, stripline, or coaxial line.

7. A branch-line directional coupler, characterized in that, include: The branch-line directional coupling circuit according to any one of claims 1-6.

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