Rat Race Coupler

Abstract

To reduce the phase error between the two output signals of a rat-race coupler. [Solution] A rat-race coupler (200) includes an annular conductor (1), a band adjustment section (2), and ports (P1-P4), where the annular conductor includes first to fourth strip conductors (11-14). The first strip conductor has a first terminal and a second terminal. The second strip conductor has a third terminal and a fourth terminal. The first terminal is connected to the third terminal through the third strip conductor. The second terminal is connected to the fourth terminal through the fourth strip conductor. The band adjustment section includes a fifth strip conductor (22), a sixth strip conductor (23), and a seventh strip conductor (24). The seventh strip conductor has a fifth terminal and a sixth terminal. The fifth terminal is connected to the third terminal through the fifth strip conductor. The sixth terminal is connected to the fourth terminal through the sixth strip conductor. The first port is connected to the fifth terminal. The second port is connected to the first terminal. The third port is connected to the second terminal.

Description

[Technical Field]

[0001] The present invention relates to an electrical component, and more particularly to a rat-race coupler. [Background technology]

[0002] A rat-race coupler is also known as a balun or hybrid ring coupler. An ideal rat-race coupler can be used to couple two input signals into one output signal, or to split one input signal into two output signals. However, the output of currently used rat-race couplers often exhibits phase errors. Therefore, finding ways to improve the phase errors of rat-race couplers is a significant challenge in this field. [Overview of the project] [Problems that the invention aims to solve]

[0003] The present invention provides a rat race coupler that can reduce the phase error of the two output signals of the rat race coupler. [Means for solving the problem]

[0004] Embodiments of the present invention provide a rat-race coupler including an annular conductor, a first band adjustment unit, a first port, a second port, and a third port. The annular conductor includes a first strip conductor, a second strip conductor, a third strip conductor, and a fourth strip conductor. The first strip conductor has a first terminal and a second terminal. The second strip conductor has a third terminal and a fourth terminal. The first terminal is connected to the third terminal through the third strip conductor. The second terminal is connected to the fourth terminal through the fourth strip conductor. The first band adjustment unit includes a fifth strip conductor, a sixth strip conductor, and a seventh strip conductor. The seventh strip conductor has a fifth terminal and a sixth terminal. The fifth terminal is connected to the third terminal through the fifth strip conductor. The sixth terminal is connected to the fourth terminal through the sixth strip conductor. The first port is connected to the fifth terminal. The second port is connected to the first terminal. The third port is connected to the second terminal. The electrical lengths from the first terminal to the second terminal through the first strip conductor, from the third terminal to the fourth terminal through the second strip conductor, and from the fifth terminal to the sixth terminal through the seventh strip conductor are all substantially 1 / 2. The electrical lengths from the first terminal to the third terminal through the third strip conductor and from the second terminal to the fourth terminal through the fourth strip conductor are both substantially 1 / 4. The electrical lengths from the third terminal to the fifth terminal through the fifth strip conductor and from the fourth terminal to the sixth terminal through the sixth strip conductor are both substantially n / 2, where n is a natural number.

[0005] In an embodiment of the present invention, n is an even number.

[0006] In an embodiment of the present invention, the rat-race coupler further includes a fourth port. The fourth port is connected to the center of the first strip conductor.

[0007] In an embodiment of the present invention, the first port, the second port, and the third port are used to connect to at least one external system having a load impedance. The impedance of the second strip conductor is 1.2 times the load impedance. The impedance of the seventh strip conductor is 0.8 times the load impedance. The impedances of the fifth strip conductor and the sixth strip conductor are both 2.8 times the load impedance.

[0008] In an embodiment of the present invention, the rat-race coupler further includes a second band adjustment unit. The second band adjustment unit includes an eighth strip conductor, a ninth strip conductor, and a tenth strip conductor. The tenth strip conductor has a seventh terminal and an eighth terminal. The seventh terminal is connected to the fifth terminal through the eighth strip conductor. The eighth terminal is connected to the sixth terminal through the ninth strip conductor. The first port is connected to the seventh terminal and is connected to the fifth terminal through the eighth strip conductor.

[0009] In an embodiment of the present invention, the first port, the second port, and the third port are used to connect to at least one external system having a load impedance. The impedance of the tenth strip conductor is 0.8 times the load impedance. The impedance of the seventh strip conductor is 1.4 times the load impedance. The impedances of the fifth strip conductor, the sixth strip conductor, the eighth strip conductor, and the ninth strip conductor are 2.8 times the load impedance.

[0010] In an embodiment of the present invention, the electrical length from the seventh terminal to the eighth terminal through the tenth strip conductor is substantially 1 / 2. The electrical lengths from the fifth terminal to the seventh terminal through the eighth strip conductor and from the sixth terminal to the eighth terminal through the ninth strip conductor are both substantially m / 2, where m is a natural number.

[0011] In an embodiment of the present invention, m is an even number.

[0012] In an embodiment of the present invention, m and n are equal.

[0013] In an embodiment of the present invention, the rat-race coupler further includes a third band adjustment unit. The third band adjustment unit includes an eleventh strip conductor, a twelfth strip conductor, and a thirteenth strip conductor. The thirteenth strip conductor has a ninth terminal and a tenth terminal. The ninth terminal is connected to the seventh terminal through the eleventh strip conductor. The tenth terminal is connected to the eighth terminal through the twelfth strip conductor. The first port is connected to the ninth terminal and is connected to the fifth terminal through the eleventh strip conductor and the eighth strip conductor.

[0014] In the embodiment of the present invention, the impedance of the seventh and tenth strip conductors is 1.4 times the load impedance. The impedance of the thirteenth strip conductor is 0.8 times the load impedance. The impedances of the fifth, sixth, eighth, ninth, eleventh, and twelfth strip conductors are 2.8 times the load impedance.

[0015] In the embodiment of the present invention, the electrical length from terminal 9 through the 13th strip conductor to terminal 10 is substantially 1 / 2. The electrical length from terminal 7 through the 11th strip conductor to terminal 9, and the electrical length from terminal 8 through the 12th strip conductor to terminal 10 are both substantially k / 2, where k is a natural number.

[0016] In the embodiments of the present invention, k is an even number.

[0017] In the embodiments of the present invention, k, m and n are equal. [Effects of the Invention]

[0018] Based on the above, the present invention forms a band adjustment section using a strip-shaped conductor having a specific length, and forms a multilayer rat-race coupler by coupling a ring-shaped conductor and one or more band adjustment sections. The rat-race coupler can reduce the phase error between the two output signals of the rat-race coupler. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram showing a rat race coupler. [Figure 2A] This is a schematic diagram of a two-layer rat race coupler as shown in one embodiment of the present invention. [Figure 2B] This is a schematic diagram of a two-layer rat race coupler as shown in one embodiment of the present invention. [Figure 3] This is a schematic diagram of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 4]This is a schematic diagram of a four-layer rat race coupler as shown in one embodiment of the present invention. [Figure 5] This is a simulation diagram of the S-parameters of a two-layer rat race coupler as shown in one embodiment of the present invention. [Figure 6] This is a simulation diagram of the S-parameters of a two-layer rat race coupler as shown in one embodiment of the present invention. [Figure 7] This is a simulation diagram of the S-parameters of a two-layer rat race coupler as shown in one embodiment of the present invention. [Figure 8] This is a simulation diagram of the S-parameters of a two-layer rat race coupler as shown in one embodiment of the present invention. [Figure 9] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 10] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 11] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 12] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 13] This is a simulation diagram of the S-parameters of a four-layer rat race coupler as shown in one embodiment of the present invention. [Figure 14] This is a simulation diagram of the S-parameters of a four-layer rat race coupler as shown in one embodiment of the present invention. [Figure 15] This is a simulation diagram of the S-parameters of a four-layer rat race coupler as shown in one embodiment of the present invention. [Figure 16] This is a simulation diagram of the S-parameters of a four-layer rat race coupler as shown in one embodiment of the present invention. [Figure 17] This is a simulation diagram of the S-parameters of a 7-layer rat race coupler as shown in one embodiment of the present invention; [Figure 18] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 19] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Figure 20] This is a simulation diagram of the S-parameters of a three-layer rat race coupler as shown in one embodiment of the present invention. [Modes for carrying out the invention]

[0020] Exemplary embodiments of the present invention are described in detail, and examples of these exemplary embodiments are shown in the accompanying drawings. Wherever possible, identical or similar parts in the drawings and description are denoted by the same reference numerals.

[0021] In the following embodiments, two components that "connect" to each other are directly connected to one another, while two components that "electrically connect" to each other are directly or indirectly connected to one another (for example, two components are connected to each other through a third component).

[0022] Figure 1 is a schematic diagram showing a rat-race coupler 100. The rat-race coupler 100 can be a structure formed by a single annular-shaped conductor #1. Thus, the rat-race coupler 100 can be referred to as a single-layer rat-race coupler, balun, or hybrid ring coupler. The annular conductor #1 is a circular or parallelogram formed by, for example, strip-shaped conductors 11, 12, 13, and 14, of which strip-shaped conductor 12 is the opposite side of strip-shaped conductor 11, and strip-shaped conductor 14 is the opposite side of strip-shaped conductor 13. More specifically, strip-shaped conductor 11 has terminals E1 and E2. Strip-shaped conductor 12 has terminals E3 and E4. Terminal E1 is connected to terminal E3 through strip-shaped conductor 13. Terminal E2 is connected to terminal E4 through strip-shaped conductor 14. Those skilled in the art will understand that the rat-race coupler referred to in the present invention can be comprised of a combination of components suitable as a microwave or millimeter-wave signal circuit, such as a waveguide, a microstrip line, a coaxial cable, or other components installed on a single-layer or multilayer substrate.

[0023] The rat-race coupler 100 may include four ports of conductive material, including ports P1, P2, P3, and P4. Port P1 can be connected to terminal E3, ports P2 and P3 can be connected to terminals E1 and E2, respectively, and port P4 can be connected to the center of the strip conductor 11. The electrical length from terminal E1 through the strip conductor 11 to terminal E2, or from terminal E3 through the strip conductor 12 to terminal E4, may be 1 / 2. The electrical length from terminal E1 through the strip conductor 13 to terminal E3, or from terminal E2 through the strip conductor 14 to terminal E4, may be 1 / 4. In each embodiment of the present invention, the electrical length is defined as the ratio of the physical length of the signal path (e.g., conductor) to the wavelength λ corresponding to the center operating frequency of the rat-race coupler 100. The wavelength referred to here is not the vacuum wavelength, but the characteristic wavelength of the signal in the signal path / guide structure. The electrical length between port P1 and port P2 can be equal to 1 / 4 (for example, the electrical length from terminal E1 through the strip conductor 13 to terminal E3), in other words, when a signal with this operating frequency is transmitted from port P1 to port P2, it will be exactly one-quarter of the wavelength. The electrical length between port P1 and port P3 can be equal to 3 / 4 (for example, the electrical length from terminal E3 through the strip conductor 12 to terminal E4 plus the electrical length from terminal E2 through the strip conductor 14 to terminal E4). The electrical length between port P1 and port P4 can be equal to 1 / 2 (for example, the electrical length from the first terminal E1 through the strip conductor 13 to terminal E3 plus half the electrical length from terminal E1 through the strip conductor 11 to terminal E2). The electrical length between port P2 and port P3 can be equal to 1 / 2 (for example, the electrical length from the first terminal E1 through the strip conductor 11 to the second terminal E2). The electrical length between port P2 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 through the strip conductor 11 to terminal E2). The electrical length between port P3 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 through the strip conductor 11 to terminal E2).

[0024] The rat-race coupler 100 can be used to split one input signal into two output signals. For example, when one input signal is input to the rat-race coupler 100 from port P1, the rat-race coupler 100 can split the input signal into two output signals and output two output signals having the same amplitude through ports P2 and P3, respectively, with a 180-degree phase difference between the output signal from port P2 and the output signal from port P3, and port P4 is isolated so that no signal is output from port P4.

[0025] The rat-race coupler 100 can be used to combine two input signals into a single output signal. For example, when two input signals are input to the rat-race coupler 100 from ports P2 and P3, respectively, the rat-race coupler 100 can combine the two input signals into a single output signal. Port P4 can act as a sum port or Σ port, and the output signal output from port P4 is the sum of the two input signals. Port P1 can act as a Δ port, and the output signal output from port P1 is the difference between the two input signals.

[0026] The rat-race coupler 100 can be connected to a load through port P1, port P2, port P3, or port P4. In one embodiment, port P1, port P2, port P3, or port P4 is used to connect to at least one external system (not shown), which has a load impedance. The impedance of the strip conductors 11, 12, 13, or 14 in the annular conductor #1 can be 1.2 times the load impedance. For example, if the load impedance is 50 ohms, the impedance of the annular conductor #1 can be 60 ohms.

[0027] In one embodiment, one or more additional band-adjusting units can be added to the structure of the rat-race coupler 100 to form an A-layer rat-race coupler comprising one annular conductor and (A-1) band-adjusting units, where A is any natural number. "a" is defined as the order index of the annular conductor or band-adjusting unit in the A-layer rat-race coupler, where a = 1, 2, ..., A. For example, a = 1 is used to represent the first component of the A-layer rat-race coupler, which is an annular conductor (i.e., annular conductor #1 directly connected to port P2, port P3, or port P4); a = 2 is used to represent the second component of the A-layer rat-race coupler, which is a band-adjusting unit (i.e., band-adjusting unit #2 directly connected to annular conductor #1 and through annular conductor #1, port P2, port P3, or port P4); and a = A is used to represent the A-th component of the A-layer rat-race coupler, which is a band-adjusting unit (i.e., band-adjusting unit #A directly connected to port P1).

[0028] The phase error generated by the A-layer rat-race coupler can be made smaller than the phase error generated by the rat-race coupler 100. For example, an additional band adjustment section can be added to the structure of the rat-race coupler 100 to form a two-layer rat-race coupler, as shown in Figure 2A.

[0029] Figure 2A is a schematic diagram showing a two-layer rat-race coupler 200 according to one embodiment of the present invention. Compared with the structure of the rat-race coupler 100 shown in Figure 1, the rat-race coupler 200 may further include an additional bandwidth adjustment section #2. The bandwidth adjustment section #2 is a U-shaped conductor formed by, for example, a strip conductor 22, a strip conductor 23, and a strip conductor 24, where the strip conductor 23 is the relative side of the strip conductor 24. The strip conductor 24 has terminals E5 and E6. Terminal E5 is connected to terminal E3 through the strip conductor 23. Terminal E6 is connected to terminal E4 through the strip conductor 24.

[0030] Port P1 can be connected to terminal E5, port P2 can be connected to terminal E1, port P3 can be connected to terminal E2, and port P4 can be connected to the center of the strip conductor 11. Port P1 can be electrically connected to the strip conductor 12 of the annular conductor #1 through the band adjustment section #2. Ports P2, P3, or P4 can be electrically connected to the strip conductors 23 and 24 of the band adjustment section #2 through the annular conductor #1. The electrical length from terminal E5 through the strip conductor 22 to terminal E6 is substantially 1 / 2, and the electrical length from terminal E3 through the strip conductor 23 to terminal E5 or from terminal E4 through the strip conductor 24 to terminal E6 is substantially n / 2. When n is a natural number, that is, when the electrical length of the strip conductor 23 (i.e., from terminal E3 through the strip conductor 23 to terminal E5) and the electrical length of the strip conductor 24 (i.e., from terminal E4 through the strip conductor 24 to terminal E6) reach an integer multiple of half a wavelength λ / 2, the rat race coupler 200 can have better performance. In order to make the electrical length of the strip conductor 23 or the strip conductor 24 reach n / 2, the strip conductor 23 or the strip conductor 24 can be a conductor having a meandering structure.

[0031] The rat-race coupler 200 is a two-layer rat-race coupler (i.e., A=2) formed by adding one additional band adjustment section #2 to the structure of the rat-race coupler 100. The electrical length between port P1 and port P2 can be equal to (2n+1) / 4 (e.g., the electrical length from terminal E1 to terminal E3 plus the electrical length from terminal E3 to terminal E5). The electrical length between port P1 and port P3 can be equal to (2n+3) / 4 (e.g., the electrical length from terminal E5 to terminal E6 plus the electrical lengths from terminal E2 to terminal E4 and from terminal E4 to terminal E6). The electrical length between port P1 and port P4 can be equal to (n+1) / 2 (e.g., the electrical length from terminal E1 to terminal E3 plus the electrical length from terminal E3 to terminal E5 and half the electrical length from terminal E1 to terminal E2). The electrical length between port P2 and port P3 can be equal to 1 / 2 (for example, the electrical length from terminal E1 to terminal E2). The electrical length between port P2 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 to terminal E2). The electrical length between port P3 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 to terminal E2).

[0032] The rat race coupler 200 can connect a load through port P1, port P2, port P3, or port P4. In one embodiment, port P1, port P2, port P3, or port P4 is used to connect to at least one external system (not shown), the external system having a load impedance. The impedance of the strip conductors 11, 12, 13, or 14 in the annular conductor #1 can be 1.2 times the load impedance. The impedance of the strip conductor 22 in the band adjustment section #2 can be 0.8 times the load impedance. The impedance of the strip conductor 23 or 24 in the band adjustment section #2 can be 2.8 times the load impedance.

[0033] For example, if the load impedance is 50 ohms, the impedance of the ring conductor #1 can be 60 ohms, the impedance of the strip conductor 22 can be 40 ohms, and the impedance of the strip conductor 23 or strip conductor 24 can be 140 ohms.

[0034] In one embodiment, as shown in Figure 2B, the rat-race coupler 200 may not have port P4, or port P4 of the rat-race coupler 200 may not be connected to any load (for example, port P4 is not connected to an external system). When one input signal is input to the rat-race coupler 200 from port P1, the rat-race coupler 200 can split the input signal into two output signals, outputting two output signals with the same amplitude through ports P2 and P3, respectively, with a 180-degree phase difference between the output signal from port P2 and the output signal from port P3. On the other hand, when two input signals are input to the rat-race coupler 200 from ports P2 and P3 respectively, port P1 can function as a delta port, and the output signal output from port P1 is the difference between the two input signals.

[0035] As shown in Figure 3, a three-layer rat-race coupler can be formed by adding an additional bandwidth adjustment section to the structure of the rat-race coupler 200. Figure 3 is a schematic diagram showing a three-layer rat-race coupler 300 according to one embodiment of the present invention. Compared with the structure of the rat-race coupler 200 shown in Figure 2A, the rat-race coupler 300 can further include a bandwidth adjustment section #3.

[0036] The bandwidth adjustment section #3 is a U-shaped conductor formed by, for example, a strip conductor 32, a strip conductor 33, and a strip conductor 34, where the strip conductor 34 is the opposite side of the strip conductor 33. The strip conductor 32 has terminals E7 and E8. Terminal E7 is connected to terminal E5 through the strip conductor 33. Terminal E8 is connected to terminal E6 through the strip conductor 34.

[0037] Port P1 can be connected to terminal E7 and to terminal E5 through the strip conductor 33. Ports P2 and P3 can be connected to terminals E1 and E2, respectively, and port P4 can be connected to the center of the strip conductor 11. Port P1 can be electrically connected to the strip conductor 22 of the band adjustment section #2 through the band adjustment section #3, and ports P2, P3, or P4 can be electrically connected to the strip conductors 33 and 34 of the band adjustment section #3 through the ring conductor #1 and the band adjustment section #2. The electrical length from terminal E7 to terminal E8 through the strip conductor 32 is substantially 1 / 2, and the electrical length from terminal E5 to terminal E7 through the strip conductor 33 or from terminal E6 to terminal E8 through the strip conductor 34 is both substantially m / 2. When m is a natural number, that is, when the electrical length of the strip conductor 33 (i.e., from terminal E5 through the strip conductor 33 to terminal E7) and the electrical length of the strip conductor 34 (i.e., from terminal E6 through the strip conductor 34 to terminal E8) reach an integer multiple of half a wavelength λ / 2, the rat race coupler 300 can have better performance. In order to make the electrical length of the strip conductor 33 or the strip conductor 34 reach m / 2, the strip conductor 33 or the strip conductor 34 can be a conductor having a meandering structure.

[0038] The rat race coupler 300 is a three-layer rat race coupler formed by adding two additional band adjustment sections #2 and #3 to the structure of the rat race coupler 100 (i.e., A=3). The electrical length between port P1 and port P2 can be equal to (2n+2m+1) / 4 (for example, the electrical length from terminal E1 to terminal E3 plus the electrical length from terminal E3 to terminal E5, and the electrical length from terminal E5 to terminal E7). The electrical length between port P1 and port P3 can be equal to (2m+2n+3) / 4 (for example, the electrical length from terminal E7 to terminal E8 plus the electrical length from terminal E2 to terminal E4, the electrical length from terminal E4 to terminal E6, and the electrical length from terminal E6 to terminal E8). The electrical length between port P1 and port P4 can be equal to (m+n+1) / 2 (for example, the electrical length from terminal E1 to terminal E3 plus the electrical length from terminal E3 to terminal E5 plus the electrical length from terminal E5 to terminal E7 plus half the electrical length from terminal E1 to terminal E2). The electrical length between port P2 and port P3 can be equal to 1 / 2 (for example, the electrical length from terminal E1 to terminal E2). The electrical length between port P2 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 to terminal E2). The electrical length between port P3 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 to terminal E2).

[0039] The rat-race coupler 300 can connect a load through port P1, port P2, port P3, or port P4. In one embodiment, port P1, port P2, port P3, or port P4 is used to connect to at least one external system (not shown), the external system having a load impedance. The impedance of the strip conductors 11, 12, 13, or 14 in the annular conductor #1 can be 1.2 times the load impedance. The impedance of the strip conductor 22 in the band adjustment section #2 can be 0.8 times the load impedance. The impedance of the strip conductor 23 or 24 in the band adjustment section #2 can be 2.8 times the load impedance. The impedance of the strip conductor 32 in the band adjustment section #3 can be 1.4 times the load impedance. The impedance of the strip conductor 33 or 34 in the band adjustment section #3 can be 2.8 times the load impedance.

[0040] For example, if the load impedance is 50 ohms, the impedance of the ring conductor #1 can be 60 ohms, the impedance of the strip conductor 22 can be 40 ohms, the impedance of the strip conductor 23 or strip conductor 24 can be 140 ohms, the impedance of the strip conductor 32 can be 70 ohms, and the impedance of the strip conductor 33 or strip conductor 34 can be 140 ohms.

[0041] In one embodiment, the rat-race coupler 300 does not have port P4, or port P4 of the rat-race coupler 300 is not connected to any load (for example, port P4 is not connected to an external system).

[0042] As shown in Figure 4, an additional bandwidth adjustment section can be added to the structure of the rat race coupler 300 to form a four-layer rat race coupler. Figure 4 is a schematic diagram showing a four-layer rat race coupler 400 according to one embodiment of the present invention. Compared to the structure of the rat race coupler 300 shown in Figure 3, the rat race coupler 400 may further include bandwidth adjustment section #4.

[0043] The bandwidth adjustment section #4 is a U-shaped conductor formed by, for example, a strip conductor 42, a strip conductor 43, and a strip conductor 44, where the strip conductor 44 is the opposite side of the strip conductor 43. The strip conductor 42 has terminals E9 and E10. Terminal E9 is connected to terminal E7 through the strip conductor 43. Terminal E10 is connected to terminal E8 through the strip conductor 44.

[0044] Port P1 can be connected to terminal E9 and is connected to terminal E5 through strip conductors 43 and 33. Ports P2 and P3 can be connected to terminals E1 and E2, respectively, and port P4 can be connected to the center of strip conductor 11. Port P1 can be electrically connected to the strip conductor 32 of band adjustment section #3 through band adjustment section #4, and ports P2, P3, or P4 can be electrically connected to the strip conductors 43 and 44 of band adjustment section #4 through ring conductor #1, band adjustment section #2, and band adjustment section #3. The electrical length from terminal E9 through strip conductor 42 to terminal E10 is substantially 1 / 2. The electrical length from terminal E7 through strip conductor 43 to terminal E9 and the electrical length from terminal E8 through strip conductor 44 to terminal E10 are both substantially k / 2. When k is a natural number, that is, when the electrical length of the strip conductor 43 (i.e., from terminal E7 through the strip conductor 43 to terminal E9) or the strip conductor 44 (i.e., from terminal E8 through the strip conductor 44 to terminal E10) reaches an integer multiple of half a wavelength λ / 2, the rat-race coupler 400 can have better performance. In order to make the electrical length of the strip conductor 43 or the strip conductor 44 reach k1 / 2, the strip conductor 43 or the strip conductor 44 can be a conductor having a meandering structure.

[0045] The rat-race coupler 400 is a four-layer rat-race coupler formed by adding three additional band-adjusting sections #2, #3, and #4 to the structure of the rat-race coupler 100 (i.e., A=4). The electrical length between port P1 and port P2 can be equal to (2n+2m+2k+1) / 4 (for example, the electrical length from terminal E1 to terminal E3 plus the electrical length from terminal E3 to terminal E5 plus the electrical length from terminal E5 to terminal E7 plus the electrical length from terminal E7 to terminal E9). The electrical length between port P1 and port P3 can be equal to (2n+2m+2k+3) / 4 (for example, the electrical length from terminal E9 to terminal E10 plus the electrical length from terminal E2 to terminal E4, from terminal E4 to terminal E6, from terminal E6 to terminal E8, and from terminal E8 to terminal E10). The electrical length between port P1 and port P4 can be equal to (n+m+k+1) / 2 (for example, the electrical length from terminal E1 to terminal E3 plus the electrical length from terminal E3 to terminal E5 plus the electrical length from terminal E5 to terminal E7 plus the electrical length from terminal E7 to terminal E9 plus half the electrical length from terminal E1 to terminal E2). The electrical length between port P2 and port P3 can be equal to 1 / 2 (for example, the electrical length from terminal E1 to terminal E2). The electrical length between port P2 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 to terminal E2). The electrical length between port P3 and port P4 can be equal to 1 / 4 (for example, half the electrical length from terminal E1 to terminal E2).

[0046] Of note, the A-layer rat-race coupler of the present invention can have more than four layers. For example, one or more additional bandwidth adjustment units #b (where b is a natural number greater than 4) can be placed between bandwidth adjustment unit #4 and port P1 to connect bandwidth adjustment unit #4 and port P1, and the one or more additional bandwidth adjustment units #b can have the same structure or impedance as bandwidth adjustment unit #4, and the connection method between the one or more additional bandwidth adjustment units #b and bandwidth adjustment unit #4 can be the same as the connection method between bandwidth adjustment unit #4 and bandwidth adjustment unit #3.

[0047] The rat-race coupler 400 can connect a load through port P1, port P2, port P3, or port P4. In one embodiment, port P1, port P2, port P3, or port P4 is used to connect to at least one external system (not shown), the external system having a load impedance. The impedance of strip conductors 11, 12, 13, or 14 in the annular conductor #1 can be 1.2 times the load impedance. The impedance of strip conductor 22 in the band adjustment section #2 can be 0.8 times the load impedance. The impedance of strip conductor 23 or 24 in the band adjustment section #2 can be 2.8 times the load impedance. The impedance of strip conductor 32 in the band adjustment section #3 can be 1.4 times the load impedance. The impedance of strip conductor 33 or 34 in the band adjustment section #3 can be 2.8 times the load impedance. The impedance of the strip conductor 42 in the bandwidth adjustment section #4 (or bandwidth adjustment section #b) can be set to 1.4 times the load impedance. The impedance of the strip conductor 43 or strip conductor 44 in the bandwidth adjustment section #4 (or bandwidth adjustment section #b) can be set to 2.8 times the load impedance.

[0048] For example, if the load impedance is 50 ohms, the impedance of the bandwidth adjustment unit #1 can be set to 60 ohms, the impedance of the strip conductor 22 can be set to 40 ohms, the impedance of the strip conductor 23 or strip conductor 24 can be set to 140 ohms, the impedance of the strip conductor 32 can be set to 70 ohms, the impedance of the strip conductor 33 or strip conductor 34 can be set to 140 ohms, the impedance of the strip conductor 42 can be set to 70 ohms, and the impedance of the strip conductor 43 or strip conductor 44 can be set to 140 ohms.

[0049] In one embodiment, the rat-race coupler 400 does not have port P4, or port P4 of the rat-race coupler 400 is not connected to any load (for example, port P4 is not connected to an external system).

[0050] Figure 5 is a simulation diagram of the S-parameters of a two-layer rat-race coupler with n=0.5 according to one embodiment of the present invention (for example, a rat-race coupler 200 having strip-shaped conductors 23 and 24 with an electrical length of 1 / 4), and curve 510 represents the S-parameters S 11 (That is, the input reflection coefficient or return loss of port P1), and curve 520 represents the S parameter S 21 (That is, the insertion loss when a signal is transmitted from port P1 to port P2), and curve 530 represents the S parameter S 31 (That is, the insertion loss when the signal is transmitted from port P1 to port P3) is represented by curve 540, the phase difference between port P2 and port P3 is represented by points 51 and 52, and the intersection of the three curves at -5dB is represented by points 51 and 52. Referring to points 51 and 52, the efficient operating bandwidth of the two-layer rat-race coupler is between approximately 18.5 GHz and 27.5 GHz, and the phase error is only about 1 degree.

[0051] Figure 6 is a simulation diagram of the S-parameters of a n=1 two-layer rat-race coupler according to one embodiment of the present invention (for example, a rat-race coupler 200 having strip-shaped conductors 23 and 24 with an electrical length of 1 / 2), and curve 610 represents the S-parameters S 11 Curve 620 represents the S parameter S 21 Curve 630 represents the S parameter S 31 The curve 640 represents the phase difference between port P2 and port P3, points 61 and 62 are the intersection points of the three curves at -5dB, and points 63 and 64 are the values ​​of curve 610 at -10dB. Referring to points 61 and 62, the effective operating bandwidth of the two-layer rat-race coupler is between approximately 15GHz and 31GHz, and the phase error is only about 2.5 degrees. Referring to points 63 and 64, the S-parameters of the two-layer rat-race coupler are as follows in the frequency bandwidth of 15.5GHz to 30.5GHz. 11 It has good gain characteristics.

[0052] FIG. 7 is a simulation diagram of S parameters of a two-layer rat-race coupler with n = 1.5 according to an embodiment of the present invention (for example, a rat-race coupler 200 having strip conductors 23 and 24 with an electrical length of 3 / 4), where curve 710 represents the S parameter S 11 and curve 720 represents the S parameter S 21 and curve 730 represents the S parameter S 31 and curve 740 represents the phase difference between port P2 and port P3, and points 71 and 72 are the intersection points of the three curves at -5 dB. Referring to points 71 and 72, the effective operating bandwidth of the two-layer rat-race coupler is between about 19.5 GHz and 26.5 GHz, and the phase error is only about 2.5 degrees.

[0053] FIG. 8 is a simulation diagram of S parameters of a two-layer rat-race coupler with n = 2 according to an embodiment of the present invention (for example, a rat-race coupler 200 having strip conductors 23 and 24 with an electrical length of 1), where curve 810 represents the S parameter S 11 and curve 820 represents the S parameter S 21 and curve 830 represents the S parameter S 31 and curve 840 represents the phase difference between port P2 and port P3, and points 81 and 82 are the intersection points of the three curves at -5 dB, and points 83 and 84 are the values of curve 810 at -10 dB. Referring to points 81 and 82, the effective operating bandwidth of the two-layer rat-race coupler is between about 17.5 GHz and 28.5 GHz, and the phase error is only about 2 degrees. Referring to points 83 and 84, in the frequency band of 19 GHz to 27 GHz, the S parameter S 11 of the two-layer rat-race coupler has good gain characteristics.

[0054] FIG. 9 is a simulation diagram of S parameters of a three-layer rat-race coupler with n = m = 0.5 according to an embodiment of the present invention (for example, a rat-race coupler 300 having strip conductors 23, 24, 33 and 34 with an electrical length of 1 / 4), where curve 910 represents the S parameter S 11 and curve 920 represents the S parameter S 21Curve 930 represents the S parameter S 31 The curve 940 represents the phase difference between port P2 and port P3, points 91 and 92 are the intersection points of the three curves at -5dB, and points 93 and 94 are the values ​​of curve 910 at -10dB. Referring to points 91 and 92, the effective operating bandwidth of the 3-layer rat-race coupler is between approximately 19GHz and 27GHz, and the phase error is only about 0 degrees. Referring to points 93 and 94, in the frequency bandwidth of 21GHz to 25GHz, the S-parameters of the 3-layer rat-race coupler are S 11 It has good gain characteristics.

[0055] Figure 10 is a simulation diagram of the S-parameters of a three-layer rat-race coupler with n=m=1 according to one embodiment of the present invention (for example, a rat-race coupler 300 having strip-shaped conductors 23, 24, 33, and 34 with an electrical length of 1 / 2), where curve 1010 represents the S-parameters S 11 Curve 1020 represents the S parameter S 21 Curve 1030 represents the S parameter S 31 The curve 1040 represents the phase difference between port P2 and port P3, points 1001 and 1002 are the intersection points of the three curves at -5dB, and points 1003 and 1004 are the values ​​of curve 1010 at -10dB. Referring to points 1001 and 1002, the effective operating bandwidth of the 3-layer rat-race coupler is between approximately 14.5GHz and 31.5GHz, and the phase error is only about 0.5 degrees. Referring to points 1003 and 1004, in the frequency bandwidth of 15GHz to 31GHz, the S-parameters of the 3-layer rat-race coupler are S 11 It has good gain characteristics.

[0056] Figure 11 is a simulation diagram of the S-parameters of a three-layer rat-race coupler with n=m=1.5 according to one embodiment of the present invention (for example, a rat-race coupler 300 having strip conductors 23, 24, 33 and 34 with an electrical length of 3 / 4), where curve 1110 represents the S-parameters. 11 Curve 1120 represents the S parameter S 21 Curve 1130 represents the S parameter S 31The curve 1140 represents the phase difference between port P2 and port P3, points 1101 and 1102 are the intersection points of the three curves at -5dB, and points 1103 and 1104 are the values ​​of curve 1110 at -10dB. Referring to points 1101 and 1102, the effective operating bandwidth of the 3-layer rat-race coupler is between approximately 20.5GHz and 25.5GHz, and the phase error is only about 0 degrees. Referring to points 1103 and 1104, in the frequency bandwidth of 21.5GHz to 24.5GHz, the S-parameters of the 3-layer rat-race coupler are S 11 It has good gain characteristics.

[0057] Figure 12 is a simulation diagram of the S-parameters of a three-layer rat-race coupler with n=m=2 according to one embodiment of the present invention (for example, a rat-race coupler 300 having strip-shaped conductors 23, 24, 33 and 34 with an electrical length of 1), where curve 1210 represents the S-parameters. 11 Curve 1220 represents the S parameter S 21 Curve 1230 represents the S parameter S 31 The curve 1240 represents the phase difference between port P2 and port P3, points 1201 and 1202 are the intersection points of the three curves at -5dB, and points 1203 and 1204 are the values ​​of curve 1210 at -10dB. Referring to points 1201 and 1202, the effective operating bandwidth of the 3-layer rat-race coupler is between approximately 17GHz and 29GHz, and the phase error is only about 0 degrees. Referring to points 1203 and 1204, in the frequency bandwidth of 18GHz to 28GHz, the S-parameters of the 3-layer rat-race coupler are S 11 It has good gain characteristics.

[0058] Figure 13 is a simulation diagram of the S-parameters of a four-layer rat-race coupler with n=m=k=0.5 according to one embodiment of the present invention (for example, a rat-race coupler 400 having strip conductors 23, 24, 33, 34, 43 and 44 with an electrical length of 1 / 4), and curve 1310 shows the S-parameters S 11 Curve 1320 represents the S parameter S 21 Curve 1330 represents the S parameter S 31The curve 1340 represents the phase difference between port P2 and port P3, points 1301 and 1302 are the intersection points of the three curves at -5dB, and points 1303, 1304, 1305, and 1306 are the values ​​of curve 1310 at -10dB. Referring to points 1301 and 1302, the effective operating bandwidth of the 4-layer rat-race coupler is between approximately 18.5GHz and 27.5GHz, with a phase error of only approximately 0 degrees. Referring to points 1303, 1304, 1305, and 1306, the S-parameters of the 4-layer rat-race coupler are in the frequency bands of 19GHz to 22GHz and 24GHz to 27GHz. 11 It has good gain characteristics.

[0059] Figure 14 is a simulation diagram of the S-parameters of a four-layer rat-race coupler with n=m=k=1 according to one embodiment of the present invention (for example, a rat-race coupler 400 having strip conductors 23, 24, 33, 34, 43 and 44 with an electrical length of 1 / 2), and curve 1410 shows the S-parameters S 11 Curve 1420 represents the S parameter S 21 Curve 1430 represents the S parameter S 31 The curve 1440 represents the phase difference between port P2 and port P3, points 1401 and 1402 are the intersection points of the three curves at -5dB, and points 1403 and 1404 are the values ​​of curve 1410 at -10dB. Referring to points 1401 and 1402, the effective operating bandwidth of the 4-layer rat-race coupler is between approximately 15GHz and 31GHz, and the phase error is only about 0.5 degrees. Referring to points 1403 and 1404, the S-parameters of the 4-layer rat-race coupler are in the frequency band of 15.5GHz to 30.5GHz. 11 It has good gain characteristics.

[0060] Figure 15 is a simulation diagram of the S-parameters of a four-layer rat-race coupler with n=m=k=1.5 according to one embodiment of the present invention (for example, a rat-race coupler 400 having strip conductors 23, 24, 33, 34, 43 and 44 with an electrical length of 3 / 4), and curve 1510 shows the S-parameters S 11 Curve 1520 represents the S parameter S21 Curve 1530 represents the S parameter S 31 The curve 1540 represents the phase difference between port P2 and port P3, points 1501 and 1502 are the intersection points of the three curves at -5dB, and points 1503, 1504, 1505, and 1506 are the values ​​of curve 1510 at -10dB. Referring to points 1501 and 1502, the effective operating bandwidth of the 4-layer rat-race coupler is between approximately 20GHz and 26GHz, and the phase error is only about 0 degrees. Referring to points 1503, 1504, 1505, and 1506, the S-parameters of the 4-layer rat-race coupler are in the frequency bands of 20.5GHz to 22.5GHz and 23.5GHz to 25.5GHz. 11 It has good gain characteristics.

[0061] Figure 16 is a simulation diagram of the S-parameters of a four-layer rat-race coupler with n=m=k=2 according to one embodiment of the present invention (for example, a rat-race coupler 400 having strip conductors 23, 24, 33, 34, 43 and 44 with an electrical length of 1), and curve 1610 shows the S-parameters S 11 Curve 1620 represents the S parameter S 21 Curve 1630 represents the S parameter S 31 The curve 1640 represents the phase difference between port P2 and port P3, points 1601 and 1602 are the intersection points of the three curves at -5dB, and points 1603 and 1604 are the values ​​of curve 1610 at -10dB. Referring to points 1601 and 1602, the effective operating bandwidth of the 4-layer rat-race coupler is between approximately 16.5GHz and 30.5GHz, and the phase error is only about 0 degrees. Referring to points 1603 and 1604, in the frequency bandwidth of 18.5GHz to 29GHz, the S-parameters of the 4-layer rat-race coupler are S 11 It has good gain characteristics.

[0062] Figure 17 is a simulation diagram of the S-parameters of a 7-layer rat race coupler with n=m=k=1 according to one embodiment of the present invention, and curve 1710 represents the S-parameter S 11 Curve 1720 represents the S parameter S 21Curve 1730 represents the S parameter S 31 The curve 1740 represents the phase difference between port P2 and port P3, points 1701 and 1702 are the intersection points of the three curves at -5dB, and points 1703 and 1704 are the values ​​of curve 1710 at -10dB. Referring to points 1701 and 1702, the effective operating bandwidth of the 7-layer rat-race coupler is between approximately 14.5GHz and 31.5GHz, and the phase error is only about 0 degrees. Referring to points 1703 and 1704, the S-parameters of the 7-layer rat-race coupler are in the frequency band of 15.5GHz to 30.5GHz. 11 It has good gain characteristics. As can be seen from Figures 13 to 17, the 7-layer rat-race coupler does not show a significant improvement in gain characteristics and phase error within the effective operating band compared to the 4-layer rat-race coupler. Therefore, when designing circuits, users can consider substituting the 7-layer rat-race coupler with a lower-cost 4-layer rat-race coupler.

[0063] Figure 18 is a simulation diagram of the S-parameters of a three-layer rat-race coupler with n=1 and m=2 according to one embodiment of the present invention (for example, a rat-race coupler 300 having strip conductors 23 and 24 with an electrical length of 1 / 2 and strip conductors 33 and 34 with an electrical length of 1), and curve 1810 shows the S-parameters S 11 Curve 1820 represents the S parameter S 21 Curve 1830 represents the S parameter S 31 The curve 1840 represents the phase difference between port P2 and port P3, points 1801 and 1802 are the intersection points of the three curves at -5dB, and points 1803 and 1804 are the values ​​of curve 1810 at -10dB. Referring to points 1801 and 1802, the effective operating bandwidth of the 3-layer rat-race coupler is between approximately 16GHz and 30GHz, and the phase error is only about 0 degrees. Referring to points 1803 and 1804, in the frequency bandwidth of 19GHz to 27GHz, the S-parameters of the 3-layer rat-race coupler are S 11 It has good gain characteristics.

[0064] Figure 19 is a simulation diagram of the S-parameters of a three-layer rat-race coupler with n=2 and m=1 according to one embodiment of the present invention (for example, a rat-race coupler 300 having strip conductors 23 and 24 with an electrical length of 1 and strip conductors 33 and 34 with an electrical length of 1 / 2), and curve 1910 represents the S-parameters S 11 Curve 1920 represents the S parameter S 21 Curve 1930 represents the S parameter S 31 The curve 1940 represents the phase difference between port P2 and port P3, points 1901 and 1902 are the intersection points of the three curves at -5dB, and points 1903 and 1904 are the values ​​of curve 1910 at -10dB. Referring to points 1901 and 1902, the effective operating bandwidth of the 3-layer rat-race coupler is between approximately 17GHz and 29GHz, and the phase error is only about 0 degrees. Referring to points 1903 and 1904, in the frequency bandwidth of 19GHz to 27GHz, the S-parameters of the 3-layer rat-race coupler are S 11 It has good gain characteristics.

[0065] Based on the contents of Figures 5 to 16 and Figures 18 to 19 described above, it can be seen that when the electrical lengths of the strip conductors 23, 24, 33, 34, and 43 conform to a specific standard, in addition to the advantage of extremely small phase error, the effective operating bandwidth range that the rat-race coupler can handle is also wider. Specifically, when n, m, or k is an even number, the rat-race coupler provided by the present invention can achieve both low phase error and a wide effective operating bandwidth.

[0066] It should be noted that the impedance of each conductor in a rat-race coupler (e.g., 100, 200, 300, or 400) can be adjusted by the user as needed, and the present invention does not limit this. Taking a three-layer rat-race coupler 300 as an example, in one embodiment, in the annular conductor #1 of the rat-race coupler 300, the impedance of strip conductor 11 is 70 ohms, the impedance of strip conductor 12 is 30 ohms, and the impedances of strip conductors 13 and 14 are 60 ohms. In the band adjustment section #2, the impedance of strip conductor 22 is 35 ohms, and the impedances of strip conductors 23 and 24 are 77 ohms. In the band adjustment section #3, the impedance of strip conductor 32 is 40 ohms, and the impedances of strip conductors 33 and 34 are 85 ohms. The S-parameters of the rat-race coupler 300 having the impedance arrangement are shown in Figure 20.

[0067] Figure 20 is a simulation diagram of the S-parameters of a 3-layer rat race coupler 300 with n=m=0.5 according to one embodiment of the present invention, and curve 2010 represents the S-parameter S 11 The curve 2020 represents the S parameter S. 21 Curve 2030 represents the S parameter S 31 The curve 2040 represents the phase difference between port P2 and port P3, points 2001 and 2002 are the intersection points of the three curves at -5dB, and points 2003 and 2004 are the values ​​of curve 2010 at -10dB. Referring to points 2001 and 2002, the effective operating bandwidth of the rat-race coupler 300 is between approximately 17.2GHz and 28.8GHz, and the phase error is only about 0.4 degrees. Referring to points 2003 and 2004, the S-parameters of the rat-race coupler 300 in the frequency band of 18GHz to 28GHz are as follows: 11 It has good gain characteristics.

[0068] In summary, the present invention forms a multilayer rat-race coupler by combining an annular conductor and one or more bandwidth adjustment units, and the bandwidth adjustment units may include strip-shaped conductors having a specific length. Compared to conventional rat-race couplers, the two output signals of the rat-race coupler of the present invention have a smaller phase error.

[0069] Finally, it should be noted that the above embodiments are used solely to illustrate the technical solutions of the present invention and are not limiting thereto. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that it is still possible to modify the technical solutions described in the above embodiments or to make equivalent substitutions to some or all of their technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. [Industrial applicability]

[0070] The present invention provides a rat-race coupler that can reduce the phase error between the two output signals of the rat-race coupler. [Explanation of symbols]

[0071] 100, 200, 300, 400: Rat Race Coupler 11, 12, 13, 14, 22, 23, 24, 32, 33, 34, 42, 43, 44: Strip conductors 51, 52, 61, 62, 63, 64, 71, 72, 81, 82, 83, 84, 91, 92, 93, 94, 1001, 1002, 1003, 1004, 1101, 1102, 1103, 1104, 1201, 1202, 1203, 1204, 1301, 1302, 1303, 1304, 1305, 1306, 1401, 1 402, 1403, 1404, 1501, 1502, 1503, 1504, 1505, 1506, 1601, 1602, 1603, 1604, 1701, 170 2, 1703, 1704, 1801, 1802, 1803, 1804, 1901, 1902, 1903, 1904, 2001, 2002, 2003, 2004: points 510, 520, 530, 540, 610, 620, 630, 640, 710, 720, 730, 740, 810, 820, 830, 840, 910, 920, 930, 940, 1010, 1020, 1030, 1040, 1110, 1120, 1130, 1140, 1210, 1220, 1230, 1240, 1310, 1320, 1 330, 1340, 1410, 1420, 1430, 1440, 1510, 1520, 1530, 1540, 1610, 1620, 1630, 1640, 1710, 1 720, 1730, 1740, 1810, 1820, 1830, 1840, 1910, 1920, 1930, 1940, 2010, 2020, 2030, 2040: Curve P1, P2, P3, P4: Ports #1: Ring conductor #2, #3, #4: Bandwidth adjustment section

Claims

1. An annular conductor comprising a first strip conductor having a first terminal and a second terminal, a second strip conductor having a third terminal and a fourth terminal, a third strip conductor, and a fourth strip conductor, wherein the first terminal is connected to the third terminal through the third strip conductor, and the second terminal is connected to the fourth terminal through the fourth strip conductor, A first bandwidth adjustment unit comprising a fifth strip-shaped conductor, a sixth strip-shaped conductor, and a seventh strip-shaped conductor having a fifth terminal and a sixth terminal, wherein the fifth terminal is connected to the third terminal through the fifth strip-shaped conductor, and the sixth terminal is connected to the fourth terminal through the sixth strip-shaped conductor, The first port connected to the fifth terminal, A second port connected to the first terminal, It comprises a third port connected to the second terminal, The electrical length from the first terminal through the first strip conductor to the second terminal, the electrical length from the third terminal through the second strip conductor to the fourth terminal, and the electrical length from the fifth terminal through the seventh strip conductor to the sixth terminal are all 1 / 2. The electrical length from the first terminal through the third strip conductor to the third terminal, and the electrical length from the second terminal through the fourth strip conductor to the fourth terminal, are both 1 / 4. A rat-race coupler in which the electrical length from the third terminal through the fifth strip conductor to the fifth terminal, and the electrical length from the fourth terminal through the sixth strip conductor to the sixth terminal are both n / 2, where n is a natural number.

2. The rat race coupler according to claim 1, wherein n is an even number.

3. The rat race coupler according to claim 1, further comprising a fourth port connected to the center of the first strip-shaped conductor.

4. The rat-race coupler according to claim 1, wherein the first port, the second port, and the third port are used to connect to at least one external system having a load impedance, the impedance of the second strip conductor is 1.2 times the load impedance, the impedance of the seventh strip conductor is 0.8 times the load impedance, and the impedances of the fifth strip conductor and the sixth strip conductor are both 2.8 times the load impedance.

5. A rat race coupler according to any one of claims 1 to 3, further comprising an eighth strip conductor, a ninth strip conductor, and a tenth strip conductor having a seventh terminal and an eighth terminal, wherein the seventh terminal is connected to the fifth terminal through the eighth strip conductor, the eighth terminal is connected to the sixth terminal through the ninth strip conductor, and the first port is connected to the seventh terminal and to the fifth terminal through the eighth strip conductor.

6. The rat-race coupler according to claim 5, wherein the first port, the second port, and the third port are used to connect to at least one external system having a load impedance, the impedance of the tenth strip conductor is 0.8 times the load impedance, the impedance of the seventh strip conductor is 1.4 times the load impedance, and the impedances of the fifth strip conductor, the sixth strip conductor, the eighth strip conductor, and the ninth strip conductor are 2.8 times the load impedance.

7. The rat race coupler according to claim 5, wherein the electrical length from the seventh terminal through the tenth strip conductor to the eighth terminal is 1 / 2, the electrical length from the fifth terminal through the eighth strip conductor to the seventh terminal and the electrical length from the sixth terminal through the ninth strip conductor to the eighth terminal are both m / 2, where m is a natural number.

8. The rat race coupler according to claim 7, wherein m is an even number.

9. The rat race coupler according to claim 7, wherein m and n are equal.

10. The rat race coupler according to claim 5, further comprising a third bandwidth adjustment unit including an eleventh strip conductor, a twelfth strip conductor, and a thirteenth strip conductor having a ninth terminal and a tenth terminal, wherein the ninth terminal is connected to the seventh terminal through the eleventh strip conductor, the tenth terminal is connected to the eighth terminal through the twelfth strip conductor, and the first port is connected to the ninth terminal and to the fifth terminal through the eleventh and eighth strip conductors.

11. The rat-race coupler according to claim 10, wherein the first port, the second port, and the third port are used to connect to at least one external system having a load impedance, the impedances of the seventh and tenth strip conductors are 1.4 times the load impedance, the impedance of the thirteenth strip conductor is 0.8 times the load impedance, and the impedances of the fifth, sixth, eighth, ninth, eleventh, and twelfth strip conductors are 2.8 times the load impedance.

12. The rat race coupler according to claim 10, wherein the electrical length from the 9th terminal through the 13th strip conductor to the 10th terminal is 1 / 2, the electrical length from the 7th terminal through the 11th strip conductor to the 9th terminal and the electrical length from the 8th terminal through the 12th strip conductor to the 10th terminal are both k / 2, where k is a natural number.

13. The rat race coupler according to claim 12, wherein k is an even number.

14. The rat race coupler according to claim 12, wherein k, m, and n are equal.

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