Communication channel forming circuit of tunable superconductive multi-path coupler

Abstract

The invention discloses a communication channel forming circuit of a tunable superconducting multi-path coupler. The circuit comprises a matching network, a low-frequency end impedance adjusting network, a high-frequency end impedance adjusting network, a low-frequency terminal multi-path coupler and a high-frequency terminal multi-path coupler, an input radio frequency signal passes through the matching network and then enters the low-frequency end impedance adjusting network and the high-frequency end impedance adjusting network, and the low-frequency end impedance adjusting network and the high-frequency end impedance adjusting network are correspondingly connected with the low-frequency terminal multi-path coupler 1 and the high-frequency terminal multi-path coupler 2 respectively to obtain 13 paths of coupling channels. And an output radio frequency signal is formed. According to the multi-path coupler, a wider working frequency band, smaller in-band ripples and smaller return loss indexes of the multi-path coupler can be realized, and the passband insertion loss and out-of-band rejection performance of the multi-path coupler can be improved at the same time.

Description

Technical Field

[0001] This invention relates to the field of anti-interference technology for ultra-shortwave communication systems, and in particular to a tunable superconducting multiplexer communication channel forming circuit based on the principle of radio frequency isolation for ultra-shortwave communication. Background Technology

[0002] Multitasking communication typically involves multiple frequency-division multiplexed channels within a relatively wide frequency band, each capable of wireless transmission and reception. Generally, each channel requires its own antenna and transceiver, with a typical 5% distance between channels. f0 is the isolation protection band, where f0 is the center frequency of the passband. However, on small communication platforms such as ships, multiple antennas placed too close together can easily cause serious mutual interference. This necessitates the use of multiplexers to connect multiple transceiver radios to the same broadband antenna for multi-tasking transmission and reception, while minimizing mutual interference between the various communication channels.

[0003] The communication channels of existing tunable multiplexers are generally constructed using conventional materials, such as metal coaxial cavities to form tunable filters, and then combined with star-shaped or piecewise linear multiplexing networks to form multiplexers.

[0004] This type of tunable multiplexer has two problems in practical applications: First, because the out-of-band reactance of the channel tunable filter increases sharply with the number of channels, the passband ripple, return loss, and frequency range covered by the multiplexer will deteriorate sharply, regardless of whether the tunable multiplexer is implemented with a star-shaped or piecewise linear structure. Second, as the number of channels increases, due to the mutual influence of the out-of-band reactance between channels, the length of the RF connection line connecting the channel filter and the multiplexing network needs to be optimized and adjusted extensively, and the increased adjustment workload increases exponentially with the number of channels.

[0005] Meanwhile, when a tunable filter implemented with a coaxial metal cavity structure is applied to a tunable multiplexer, its input and output structures must be specially designed to ensure that the out-of-band reactance is much less than a quarter wavelength within the operating frequency band; otherwise, a high-performance radio frequency signal cannot be formed.

[0006] Furthermore, tunable filters made using superconducting materials exhibit extremely low insertion loss and excellent out-of-band rejection performance. Therefore, using superconducting tunable filters to realize multiplexers is almost a necessary approach to achieving high-performance multiplexers. However, due to the special properties of the superconducting tunable filter material, it is difficult to achieve an input-output structure much smaller than a quarter wavelength. At the same time, the limitation of operating temperature also makes it difficult to achieve online real-time debugging.

[0007] Therefore, to realize high-performance multiplexers based on superconducting technology, it is urgent to adopt new coupling structures and new communication channel formation methods to solve the problems of large passband ripple, high return loss, narrow frequency range, and large tuning workload in existing tunable multiplexers implemented using star-shaped and piecewise linear coupling networks. This will ensure the communication channel performance of broadband multiplexers. Summary of the Invention

[0008] The purpose of this invention is to solve the problems of large passband ripple, high return loss, narrow frequency range, and large tuning workload caused by the use of conventional star-shaped and piecewise linear coupling structures in the process of realizing high-performance superconducting tunable multi-coupled networks based on superconducting materials. By updating the channel formation method, the channel RF performance of the superconducting multi-coupler is guaranteed, while reducing the debugging workload.

[0009] This invention provides a communication channel forming circuit for a tunable superconducting multiplexer, including a matching network, a low-frequency impedance adjustment network, a high-frequency impedance adjustment network, a low-frequency segment multiplexer, and a high-frequency segment multiplexer.

[0010] After passing through the matching network, the input RF signal enters two parts: the low-frequency impedance adjustment network and the high-frequency impedance adjustment network. The low-frequency impedance adjustment network and the high-frequency impedance adjustment network are respectively connected to the low-frequency terminal multiplexer 1 and the high-frequency terminal multiplexer 2 to obtain 13 coupling channels, forming the output RF signal.

[0011] Both the low-frequency impedance adjustment network and the high-frequency impedance adjustment network are composed of transmission lines and lumped elements; both the low-frequency sub-multiplexer and the high-frequency sub-multiplexer are composed of superconducting tunable filters and metal coaxial line multiplexing networks.

[0012] The matching network is specifically implemented as follows: P1 is the input terminal, which receives the radio frequency signal. The high-frequency and low-frequency matching networks are formed by coaxial lines L01-L06. P1 is directly connected to coaxial line L01. Coaxial line L01 is connected to coaxial lines L02 and L03 in a star-point manner. The other end of coaxial line L02 is connected to the output terminal P2 and coaxial line L04 respectively. The other end of coaxial line L03 is connected to coaxial lines L05 and L06. Coaxial lines L04 and L06 are open-circuited. Coaxial line L05 is directly connected to the output terminal P3.

[0013] The impedance at the low-frequency end is changed by adjusting the lengths of coaxial lines L02 and L04, and the impedance at the high-frequency end is changed by adjusting the lengths of coaxial lines L03, L05, and L06. The output terminal P2 is connected to the low-frequency impedance adjustment network, and the output terminal P3 is connected to the high-frequency impedance adjustment network.

[0014] The low-frequency impedance adjustment network is specifically implemented as follows: a low-pass filter circuit is formed by inductors L1-L5 and capacitors C1-C4. One end of inductor L1 is connected to the output terminal P2, and the other end of inductor L1 is connected to one end of capacitor C1 and one end of inductor L2; the other end of inductor L2 is connected to one end of inductor L3 and one end of capacitor C2; the other end of inductor L3 is connected to one end of inductor L4 and one end of capacitor C3; the other end of inductor L4 is connected to one end of inductor L5 and one end of capacitor C4; the other end of inductor L5 is connected to the output terminal PL; and the other ends of capacitors C1-C4 are all grounded.

[0015] The high-frequency impedance adjustment network is specifically implemented as follows: a low-pass filter circuit is formed by inductors L6-L9 and capacitors C5-C9. One end of capacitor C5 is connected to the output terminal P3, and the other end is connected to one end of capacitor C6 and one end of inductor L6; the other end of capacitor C6 is connected to one end of capacitor C7 and one end of inductor L7; the other end of capacitor C7 is connected to one end of capacitor C8 and one end of inductor L8; the other end of capacitor C8 is connected to one end of capacitor C9 and one end of inductor L9; the other end of capacitor C9 is connected to the output terminal PH; and the other ends of inductors L6-L9 are all grounded.

[0016] The low-frequency terminal multiplexer is specifically implemented as follows: the output terminal PL is connected in a star-point manner to coaxial lines L11-L17; the other end of coaxial line L11 is connected to one end of filter 1, and the other end of filter 1 is connected to output terminal P01; the other end of coaxial line L12 is connected to one end of filter 2, and the other end of filter 2 is connected to output terminal P02; the other end of coaxial line L13 is connected to one end of filter 3, and the other end of filter 3 is connected to output terminal P03; the other end of coaxial line L14 is connected to one end of filter 4, and the other end of filter 4 is connected to output terminal P04; the other end of coaxial line L15 is connected to one end of filter 5, and the other end of filter 5 is connected to output terminal P05; the other end of coaxial line L16 is connected to one end of filter 6, and the other end of filter 6 is connected to output terminal P06; the other end of coaxial line L17 is connected to one end of filter 7, and the other end of filter 7 is connected to output terminal P07.

[0017] The high-frequency terminal multiplexer is specifically implemented as follows: the output terminal PH is connected to coaxial lines L21-L26 in a star-point configuration; the other end of coaxial line L21 is connected to one end of filter 8, and the other end of filter 8 is connected to the output terminal P08; the other end of coaxial line L22 is connected to one end of filter 9, and the other end of filter 9 is connected to the output terminal P09; the other end of coaxial line L23 is connected to one end of filter 10, and the other end of filter 10 is connected to the output terminal P10; the other end of coaxial line L24 is connected to one end of filter 11, and the other end of filter 11 is connected to the output terminal P11; the other end of coaxial line L25 is connected to one end of filter 12, and the other end of filter 12 is connected to the output terminal P12; the other end of coaxial line L26 is connected to one end of filter 13, and the other end of filter 13 is connected to the output terminal P13.

[0018] Beneficial effects of this invention: 1. By combining a low / high frequency band impedance adjustment network, a matching network, and a low / high frequency band multi-coupler to achieve impedance isolation, a superconducting multi-coupler channel formation scheme can achieve a wider operating bandwidth, lower in-band ripple, and lower return loss performance for the multi-coupler.

[0019] 2. The low / high frequency segment multi-couplers can be designed separately, which greatly reduces the workload of optimization and debugging.

[0020] Using superconducting technology to realize tunable filters can simultaneously improve the passband insertion loss and out-of-band rejection performance of multi-couplers. Attached Figure Description

[0021] Figure 1 This is a diagram of a traditional multi-channel coupler structure. Figure 2 Performance diagram of a 13-channel RF superconducting filter implemented using a traditional piecewise linear coupling network; Figure 3 An overall scheme for the communication channel forming circuit of a tunable superconducting multiplexer; Figure 4 For low-frequency terminal multiplexers and high-frequency terminal multiplexers; Figure 5 To match the network circuit; Figure 6 This is a low-frequency impedance adjustment network circuit. Figure 7 This is a high-frequency impedance adjustment network circuit. Figure 8 Insertion loss performance of the RF channels of a 13-channel RF superconducting multiplexer; Figure 9 The return loss performance of the RF channel of the 13-channel superconducting multiplexer is evaluated. Detailed Implementation

[0022] Existing tunable multiplexers typically use conventional materials for their communication channels, such as a metal coaxial cavity to form a tunable filter, which is then combined with a star-shaped or piecewise linear multiplexing network to form the multiplexer. Figure 1 As shown, the upper figure is a diagram of a star-shaped multiplexer, and the lower figure is a diagram of a folded-out multiplexer.

[0023] This type of tunable multiplexer has two problems in practical applications: First, the passband ripple, return loss, and frequency range covered by the channel all deteriorate sharply; second, the out-of-band reactances of multiple channels significantly influence each other, and the debugging workload increases exponentially with the number of channels. The performance of communication channels implemented in a traditional manner is as follows: Figure 2 As shown, the multi-channel coupling effect of the 13 channels is not ideal, with large insertion loss and large passband ripple.

[0024] The specific scheme of the superconducting multiplexer communication channel formation method based on the radio frequency isolation principle in this invention is as follows: Figure 3 As shown.

[0025] Figure 3 In the process, the input radio frequency signal passes through the matching network and then enters two parts: the low-frequency impedance adjustment network and the high-frequency impedance adjustment network. The low-frequency impedance adjustment network and the high-frequency impedance adjustment network are respectively connected to the low-frequency terminal multiplexer 1 and the high-frequency terminal multiplexer 2 to obtain 13 coupling channels, forming the output radio frequency signal.

[0026] Both the low-frequency impedance adjustment network and the high-frequency impedance adjustment network are composed of transmission lines and lumped elements. Both the low-frequency terminal multiplexer and the high-frequency terminal multiplexer are composed of superconducting tunable filters and metal coaxial line multiplexer networks.

[0027] The low-frequency impedance adjustment network exhibits low-pass combined multiplexer characteristics, while the high-frequency impedance adjustment network exhibits high-pass combined multiplexer characteristics, achieving RF isolation between the low-frequency and high-frequency ends. This allows the low-frequency multiplexer and low-frequency impedance adjustment network to be designed independently, as well as the high-frequency multiplexer and high-frequency impedance adjustment network. Both can be connected together through a matching network to form 13 communication channels in the UHF band. The gap between the low-frequency and high-frequency ends is less than 3%. The isolation protection bandwidth of f0 can be supplemented by adjusting the capacitor of the low / high frequency impedance adjustment network, thereby achieving a small-range adjustment of the operating frequency band of the low / high frequency impedance adjustment network. f0 provides isolation protection bandwidth, enabling full-band operation.

[0028] The circuit of the implemented 13-channel RF superconducting multiplexer is as follows: Figure 4As shown in the diagram. The top diagram represents the low-frequency end, and the bottom diagram represents the high-frequency end. The low-frequency end uses a star-point connection to coaxial lines L11-L17, with each end of coaxial lines L11-L17 connected to a filter. The other ends of the filters are connected to the output terminals P01-P07 respectively. The high-frequency end also uses a star-point connection to coaxial lines L21-L26, with each end of coaxial lines L21-L26 connected to a filter. The other ends of the filters are connected to the output terminals P08-P13 respectively. In this way, the 13 filters are divided into 7 low-frequency channels and 6 high-frequency channels.

[0029] like Figure 5 The diagram shows the matching network circuit. P1 is the input terminal of the overall 13-channel RF superconducting multiplexer. The input RF signal forms a matching network through coaxial cables L01-L06. Input terminal P1 is directly connected to coaxial cable L01. Coaxial cable L01 is connected to coaxial cables L02 and L03 in a star-point configuration. The other end of coaxial cable L02 is connected to output terminal P2 and coaxial cable L04 respectively. The other end of coaxial cable L03 is connected to coaxial cables L05 and L06. Coaxial cables L04 and L06 are open-circuited. Coaxial cable L05 is directly connected to output terminal P3. The impedance at the low-frequency end is changed by adjusting the lengths of coaxial cables L02 and L04, while the impedance at the high-frequency end is changed by adjusting the lengths of coaxial cables L03, L05, and L06. (P2 connection) Figure 6 P2 and P3 connections of the mid-to-low frequency impedance adjustment network Figure 7 P3 of the high-frequency impedance adjustment network.

[0030] like Figure 6 The diagram shows a low-frequency impedance adjustment network circuit. It uses inductors L1-L5 and capacitors C1-C4 to form a circuit similar to a low-pass filter. One end of inductor L1 is connected to the output terminal P2, and the other end of inductor L1 is connected to one end of capacitor C1 and one end of inductor L2. The other end of inductor L2 is connected to one end of inductor L3 and one end of capacitor C2. The other end of inductor L3 is connected to one end of inductor L4 and one end of capacitor C3. The other end of inductor L4 is connected to one end of inductor L5 and one end of capacitor C4. The other end of inductor L5 is connected to the output terminal PL. The other ends of capacitors C1-C4 are all grounded. However, its circuit performance is not that of a traditional low-pass filter; its function is to change the impedance of the entire low-frequency end in the overall structure to achieve matching.

[0031] like Figure 7The diagram shows a high-frequency impedance adjustment network circuit. Similar to the low-frequency impedance adjustment network, it uses capacitors C5-C9 and inductors L6-L9 to form a circuit resembling a high-pass filter. One end of capacitor C5 is connected to the output terminal P3, and the other end is connected to one end of capacitor C6 and one end of inductor L6; the other end of capacitor C6 is connected to one end of capacitor C7 and one end of inductor L7; the other end of capacitor C7 is connected to one end of capacitor C8 and one end of inductor L8; the other end of capacitor C8 is connected to one end of capacitor C9 and one end of inductor L9; the other end of capacitor C9 is connected to the output terminal PH; and the other ends of inductors L6-L9 are all grounded. However, its circuit performance is not that of a traditional high-pass filter; its function is to change the impedance of the entire high-frequency end in the overall structure to achieve matching.

[0032] First, adjust Figure 4 The length of the coaxial line in Figure 5 The length of the coaxial cable is used to initially couple the entire 13-channel filter, and then... Figure 6 , Figure 7 The structure in is as follows Figure 3 As shown, an overall structure is added, and the values ​​of capacitors and inductors are adjusted to achieve the final coupling. The achieved RF channel insertion loss performance is as follows: Figure 8 As shown, the achieved RF channel return loss performance is as follows: Figure 9 As shown.

[0033] from Figure 8 and Figure 9 As can be seen from the results, the superconducting multiplexer based on the radio frequency isolation principle described in this patent can achieve an in-band ripple of less than 0.2 dB and a return loss of better than 11 dB in the radio frequency channel. This result verifies the practicality of this patent.

[0034] The sub-multiplexers at the low / high frequency ends are implemented using a classic star-shaped scheme, and are jointly optimized with the impedance adjustment network at the low / high frequency ends to achieve good passband performance. Because each communication channel after separation has a small number of paths and a narrow bandwidth, good passband performance can be easily achieved.

[0035] Radio frequency isolation between low-frequency and high-frequency segment multiplexers can be achieved through low-frequency and high-frequency impedance adjustment networks, thereby ensuring good overall multi-channel communication formation quality. Furthermore, since the number of channels in each low-frequency / high-frequency segment multiplexer is relatively small, the required number of debugging operations can be significantly reduced.

[0036] Implementation principle: The key technical points of the superconducting multiplexer communication channel formation method based on the radio frequency isolation principle of this invention are as follows: 1. The entire radio frequency bandwidth is divided into multiple sub-bands using the radio frequency isolation principle, and radio frequency isolation between these sub-bands is achieved. This technology ensures that the broadband superconducting multiplexer operating within a wide bandwidth has a large number of channels, low in-band ripple, and low return loss; 2. Through isolation between sub-bands, sub-multiplexers with relatively narrow bandwidth and a relatively small number of channels can be designed independently, further optimizing the channel performance of the multiplexer and reducing the workload of optimization and debugging.

Claims

1. A communication channel forming circuit of a tunable superconducting multi-coupler, characterized by, This includes matching networks, low-frequency impedance adjustment networks, high-frequency impedance adjustment networks, low-frequency terminal multiplexers, and high-frequency terminal multiplexers. After passing through the matching network, the input RF signal enters two parts: the low-frequency impedance adjustment network and the high-frequency impedance adjustment network. The low-frequency impedance adjustment network and the high-frequency impedance adjustment network are respectively connected to the low-frequency terminal multiplexer 1 and the high-frequency terminal multiplexer 2 to obtain 13 coupling channels, forming the output RF signal.

2. A tunable superconducting multi-coupler communication channel forming circuit according to claim 1, wherein, Both the low-frequency impedance adjustment network and the high-frequency impedance adjustment network are composed of transmission lines and lumped elements; both the low-frequency terminal multiplexer and the high-frequency terminal multiplexer are composed of superconducting tunable filters and metal coaxial line multiplexer networks.

3. The communication channel forming circuit of a tunable superconducting multiplexer according to claim 1, characterized in that, The matching network is specifically implemented as follows: P1 is the input terminal, receiving the radio frequency signal. It forms a matching network for the high-frequency and low-frequency ends through coaxial cables L01-L06. P1 is directly connected to coaxial cable L01. Coaxial cable L01 is connected to coaxial cables L02 and L03 in a star-point configuration. The other end of coaxial cable L02 is connected to the output terminal P2 and coaxial cable L04 respectively. The other end of coaxial cable L03 is connected to coaxial cables L05 and L06. Coaxial cables L04 and L06 are open-circuited. Coaxial cable L05 is directly connected to the output terminal P3. The impedance at the low-frequency end is changed by adjusting the lengths of coaxial lines L02 and L04, and the impedance at the high-frequency end is changed by adjusting the lengths of coaxial lines L03, L05, and L06. Output terminal P2 is connected to the low-frequency impedance adjustment network, and output terminal P3 is connected to the high-frequency impedance adjustment network.

4. The communication channel forming circuit of a tunable superconducting multiplexer according to claim 3, characterized in that, The low-frequency impedance adjustment network is specifically implemented as follows: a low-pass filter circuit is formed by inductors L1-L5 and capacitors C1-C4. One end of inductor L1 is connected to the output terminal P2, and the other end of inductor L1 is connected to one end of capacitor C1 and one end of inductor L2; the other end of inductor L2 is connected to one end of inductor L3 and one end of capacitor C2; the other end of inductor L3 is connected to one end of inductor L4 and one end of capacitor C3; the other end of inductor L4 is connected to one end of inductor L5 and one end of capacitor C4; the other end of inductor L5 is connected to the output terminal PL; and the other ends of capacitors C1-C4 are all grounded.

5. The communication channel forming circuit of a tunable superconducting multiplexer according to claim 3, characterized in that, The high-frequency impedance adjustment network is specifically implemented as follows: a low-pass filter circuit is formed by inductors L6-L9 and capacitors C5-C9. One end of capacitor C5 is connected to the output terminal P3, and the other end is connected to one end of capacitor C6 and one end of inductor L6; the other end of capacitor C6 is connected to one end of capacitor C7 and one end of inductor L7; the other end of capacitor C7 is connected to one end of capacitor C8 and one end of inductor L8; the other end of capacitor C8 is connected to one end of capacitor C9 and one end of inductor L9; the other end of capacitor C9 is connected to the output terminal PH; and the other ends of inductors L6-L9 are all grounded.

6. The communication channel forming circuit of a tunable superconducting multiplexer according to claim 4, characterized in that, The low-frequency terminal multiplexer is specifically implemented as follows: the output terminal PL is connected in a star-point manner to coaxial lines L11-L17; the other end of coaxial line L11 is connected to one end of filter 1, and the other end of filter 1 is connected to output terminal P01; the other end of coaxial line L12 is connected to one end of filter 2, and the other end of filter 2 is connected to output terminal P02; the other end of coaxial line L13 is connected to one end of filter 3, and the other end of filter 3 is connected to output terminal P03; the other end of coaxial line L14 is connected to one end of filter 4, and the other end of filter 4 is connected to output terminal P04; the other end of coaxial line L15 is connected to one end of filter 5, and the other end of filter 5 is connected to output terminal P05; the other end of coaxial line L16 is connected to one end of filter 6, and the other end of filter 6 is connected to output terminal P06; the other end of coaxial line L17 is connected to one end of filter 7, and the other end of filter 7 is connected to output terminal P07.

7. The communication channel forming circuit of a tunable superconducting multiplexer according to claim 5, characterized in that, The high-frequency terminal multiplexer is specifically implemented as follows: the output terminal PH is connected to coaxial lines L21-L26 in a star-point configuration; the other end of coaxial line L21 is connected to one end of filter 8, and the other end of filter 8 is connected to the output terminal P08; the other end of coaxial line L22 is connected to one end of filter 9, and the other end of filter 9 is connected to the output terminal P09; the other end of coaxial line L23 is connected to one end of filter 10, and the other end of filter 10 is connected to the output terminal P10; the other end of coaxial line L24 is connected to one end of filter 11, and the other end of filter 11 is connected to the output terminal P11; the other end of coaxial line L25 is connected to one end of filter 12, and the other end of filter 12 is connected to the output terminal P12; the other end of coaxial line L26 is connected to one end of filter 13, and the other end of filter 13 is connected to the output terminal P13.

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