CN117175171A

CN117175171A - Reconfigurable microwave filter circulator with self-interference isolation adjustable function

Info

Publication number: CN117175171A
Application number: CN202311113009.9A
Authority: CN
Inventors: 杨涛; 宁宇航; 魏治华; 纪佩绫
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2023-08-31
Filing date: 2023-08-31
Publication date: 2023-12-05

Abstract

The application relates to the field of wireless communication systems, in particular to a reconfigurable microwave filter circulator with a self-interference isolation adjustable function, which comprises: the antenna comprises an antenna end, a transmitting end and a receiving end, wherein a multi-order transmitting filter is connected between the antenna end and the transmitting end, a multi-order receiving filter is connected between the antenna end and the receiving end, the multi-order receiving filter and the multi-order transmitting filter both comprise a plurality of LC resonators which are arranged in parallel, one ends of the LC resonators are grounded, and the other ends of the LC resonators are coupled in a mixed mode through a varactor and a high-impedance microstrip line, so that the antenna end and the receiving end are provided with a plurality of transmission zeros and support space-time modulation. The application can realize high isolation between the transmitting end and the receiving end and reconfigurable isolation performance, flexibly regulate and control and change the performance of the receiving and transmitting components in the full duplex system, and greatly improve the multifunctional, switchable and strong reconfigurable performance of the system.

Description

Reconfigurable microwave filter circulator with self-interference isolation adjustable function

Technical Field

The application relates to the technical field of wireless communication systems, in particular to a reconfigurable microwave filter circulator with a self-interference isolation adjustable function.

Background

In modern wireless communication technology, a full duplex system is widely studied by students because it can support uplink and downlink simultaneous co-frequency operation, and widens channel capacity, but the full duplex system has a major problem that a high-power signal of a transmitting end leaks into a receiving end circuit in the full duplex system, and the whole communication system is greatly affected, so realizing high isolation from the transmitting end to the receiving end is a main objective of solving the self-interference problem, and the self-interference signal in the full duplex system includes: (1) high power signal reflection at the antenna; (2) self-interference signals generated by external and multipath effects; (3) the high power signal at the transmitting end leaks to the receiving end.

In reported documents, in order to solve the self-interference problem, a self-interference cancellation technology is mostly adopted in devices such as circulators, and a digital signal processing method such as a DSP is frequently adopted to eliminate self-interference signals, so that high isolation is generated. However, the digital module is greatly complicated in the frame of the radio frequency transceiver system, and the operation thereof is complicated, and the integration of the digital signal module and the radio frequency analog signal transceiver circuit is another problem, which greatly increases the complexity of the system by introducing redundant DACs and ADCs, and the reported self-interference cancellation technology cannot support the high reconfigurability of the isolation, so that in order to realize the high isolation between the transmitting end and the receiving end at the radio frequency transceiver module and make the isolation reconfigurable, a reconfigurable microwave filter circulator with the function of adjusting the self-interference isolation is required to be provided.

Disclosure of Invention

The application aims at: the reconfigurable microwave filter circulator with the self-interference isolation degree adjustable function can freely adjust the isolation degree from a transmitting end to a receiving end, eliminates introduced signals by self-interference signals by controlling the amplitude and the phase of a self-interference cancellation path circuit based on a self-interference cancellation technology, so as to realize high isolation degree, and can reconstruct the working frequency of cancellation points due to the reconfigurability of the self-interference cancellation path circuit, complete the reconfigurability of the cancellation point positions and realize the reconfigurability isolation degree, so that the problem that the existing self-interference cancellation technology cannot support the high reconfigurability of the isolation degree is solved.

In order to solve the above-mentioned prior art problems, the present application provides a reconfigurable microwave filter circulator with a self-interference isolation adjustable function, which has: an antenna end, a transmitting end and a receiving end,

a multi-order transmitting filter is connected between the antenna end and the transmitting end and comprises a plurality of LC resonators which are arranged in parallel, one ends of the LC resonators are grounded, and the other ends of the LC resonators are coupled with a high-impedance microstrip line in a mixed mode through a varactor;

the multi-order receiving filter comprises a plurality of LC resonators which are arranged in parallel, one ends of the LC resonators are grounded, and the other ends of the LC resonators are in mixed coupling with the high-impedance microstrip line through a varactor;

the multi-order transmitting filter and the multi-order receiving filter are both connected with an antenna end, an LC resonator R0 is arranged in parallel at the joint of the multi-order transmitting filter and the multi-order receiving filter, one end of the LC resonator R0 is connected with the antenna end, and the other end of the LC resonator R0 is grounded;

the LC resonator R0, the first-order LC resonator of the multi-order transmitting filter and the first-order LC resonator of the multi-order receiving filter are in mixed coupling through a varactor diode and a high-impedance microstrip line to form an integral framework of a filter circulator, and the integral framework is provided with a plurality of transmission zeros and supports space-time modulation;

the signal generated by the transmitting end is transmitted and coupled through a plurality of LC resonators and then flows to the receiving end, namely the signal S23, and the signal S23 is isolated.

Further, the multi-order transmitting filter and the multi-order receiving filter are all three-order, namely the multi-order receiving filter comprises LC resonators R1, R2 and R3, the multi-order transmitting filter comprises LC resonators R4, R5 and R6,

the coupling between the LC resonator R0 and the LC resonator R1 is M01, the coupling between the LC resonator R0 and the LC resonator R4 is M04, and the coupling between the LC resonator R1 and the LC resonator R4 is M14;

the coupling between the LC resonator R1 and the LC resonator R2 is M12, and the coupling between the LC resonator R2 and the LC resonator R3 is M23;

the coupling between the LC resonator R4 and the LC resonator R5 is M45, and the coupling between the LC resonator R5 and the LC resonator R6 is M56;

and M01, M04, M14, M12, M23, M45 and M56 are varactors and high-impedance microstrip lines which are connected in parallel, provide a plurality of transmission zeros for the filter circulator, support space-time modulation, eliminate magnetic bias and form a nonmagnetic filter circulator.

Furthermore, three external coupling capacitors J0, J1, J2 are respectively introduced into the antenna end, the receiving end and the transmitting end, and the coupling capacitors J0, J1, J2 are varactors and are used for matching with external ports.

Further, a self-interference cancellation path 1 is grafted between the R2 and the R5, the path signal corresponds to a frequency point f1, a self-interference cancellation path 2 is grafted between the R3 and the R6, the path signal corresponds to a frequency point f2, the self-interference cancellation path 1 counteracts the signal S23 at the frequency point f1, and the self-interference cancellation path 2 counteracts the signal S23 at the frequency point f2, so that high isolation performance with two counteraction points is obtained.

Further, the self-interference cancellation path 1\self-interference cancellation path 2 is reconfigurable in the amplitude and the phase of the frequency point f 1\frequency point f2, the signal S23 is counteracted by controlling the amplitude and the phase of the self-interference cancellation path 1\self-interference cancellation path 2 in the frequency point f 1\frequency point f2, the high-isolation performance is realized, the phases of the self-interference cancellation path 1 and the self-interference cancellation path 2 are adjustable, the working center frequency point is adjustable, the high-isolation performance can be switched between broadband isolation and narrowband isolation, and the flexible reconfigurable isolation performance is realized.

Further, the cancellation of the signal S23 at the frequency point f1 by the self-interference cancellation path 1 specifically includes:

the method comprises the steps of controlling the amplitude of a signal of a self-interference cancellation path 1 at a frequency point f1 to be the same as the amplitude of an S23 signal at the frequency point f1, and enabling the phase of the signal of the self-interference cancellation path 1 at the frequency point f1 to be 180 degrees different from the phase of the S23 signal at the frequency point f 1;

similarly, the cancellation of the signal S23 at the frequency point f2 by the self-interference cancellation path 2 is specifically:

the amplitude of the signal of the self-interference cancellation path 2 at the frequency point f2 is controlled to be the same as the amplitude of the S23 signal at the frequency point f2, and the phase of the signal of the self-interference cancellation path 2 at the frequency point f2 is 180 degrees different from the phase of the S23 signal at the frequency point f2.

Further, the self-interference cancellation path 1 includes 2 external varactors CkBs, 2 parallel NRNs and 1 resistor, the 2 varactors CkBs are connected at two ends of the resistor, one end of the NRN is connected between the resistor and the varactors CkBs, the other end is grounded, and the self-interference cancellation path 1 is respectively connected to LC resonators R3 and R6 through the 2 varactors CkBs;

the self-interference cancellation signal is amplitude regulated by controlling the bias voltage applied to the 2 varactors CkBs.

Further, the NRN of the self-interference cancellation path 1 includes an inductor and a varactor CBs connected in parallel, one ends of the inductor and the varactor CBs are grounded, one ends of the inductor and the varactor CBs are connected with a varactor CkBs, the self-interference cancellation signal is subjected to phase regulation by controlling bias voltages loaded on the 2 varactors CBs, and the phase is controlled to be adjusted at 0-360 degrees, so that the phase requirement of cancellation of the signal S23 at the frequency point f1 is met.

Further, the self-interference cancellation path 2 includes 2 varactors ckbs, 2 parallel NRNs and 1 resistor, the 2 varactors ckbs are connected at two ends of the resistor, one end of the NRN is connected between the resistor and the varactors ckbs, the other end is grounded, and the self-interference cancellation path 2 is respectively connected with LC resonators R2 and R5 through the 2 varactors ckbs;

Further, the NRN of the self-interference cancellation path 2 includes an inductor and a varactor CBss connected in parallel, one ends of the inductor and the varactor CBss are grounded, one ends of the inductor and the varactor CBss are connected with the varactor ckbs, the self-interference cancellation signal is phase-regulated by controlling bias voltages loaded on the 2 varactors CBss, the phase is controlled to be adjusted at 0-360 degrees, and the phase requirement of cancellation of the signal S23 at the frequency point f2 is met.

The beneficial effects of the application are as follows:

the application relates to a reconfigurable microwave filter circulator with a self-interference isolation adjustable function, which is characterized in that 7 parallel LC resonators are in mixed coupling through a varactor diode and a high-impedance microstrip line, so that more transmission zero points are introduced for the circuit structure, space-time modulation is supported, a microwave nonmagnetic reconfigurable filter circulator is realized, the circulator architecture of the 7 LC resonators enables the original signal path from a transmitting end to a receiving end to be prolonged, and the isolation is enhanced for the first time.

The application relates to a reconfigurable microwave filter circulator with a self-interference isolation degree adjustable function, which is based on a self-interference cancellation technology, and additionally introduces two self-interference cancellation path signals to cancel the original isolation signals, and further realizes high isolation degree due to the introduction of two cancellation points. At the same time, since the additional signal path introduced is a weak coupling, no impact is made on the other performance of the filter loop circuit.

The application provides a reconfigurable microwave filter circulator with a self-interference isolation degree adjustable function, which firstly proposes that a non-resonance point phase shifting circuit is applied to a self-interference cancellation circulator, the amplitude of the self-interference cancellation circulator can be adjusted by controlling a coupling varactor which is loaded outside the circuit, the phase of the self-interference cancellation circulator can be adjusted by adjusting a loaded grounding varactor, and the center frequency of the self-interference cancellation circulator can be adjusted, so that the performance of high isolation degree can be switched between broadband isolation and narrowband isolation at will, and flexible reconfigurable isolation degree performance can be realized.

The application relates to a reconfigurable microwave filter circulator with a self-interference isolation adjustable function, which is structurally characterized in that a filter circulator with a third-order filter response is realized, the filter circulator has multiple transmission zeros, and the center frequency of the circulator is also reconfigurable due to the reconfigurability of the center frequency of an LC resonator, so that a flexible working mode is realized.

Drawings

FIG. 1 is a block diagram of the overall circuit of the present application;

FIG. 2 is a schematic circuit diagram of a self-interference cancellation path;

FIG. 3 is a schematic diagram of a circuit test according to the present application;

FIG. 4 is a graph showing the S-parameter passband test result of the present application;

FIG. 5 is a graph showing the S-parameter return loss test results of the present application;

FIG. 6 is a graph showing the results of the S-parameter isolation test of the present application;

fig. 7 (a) and 7 (b) are the front and back sides of the physical drawings of the present application, respectively.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Example 1:

referring to fig. 1, the present application is a reconfigurable microwave filter circulator with a self-interference isolation adjustable function, having: an antenna end, a transmitting end and a receiving end,

As shown in fig. 1, the overall filter circulator structure proposed by the present application is formed by seven parallel LC resonators R0, R1, R2, R3, R4, R5, R6 to form a theme framework, where R1, R2, R3 are respectively a first-order LC resonator, a second-order LC resonator, and a second-order LC resonator in the multi-order receiving filter, and R4, R5, R6 are respectively a first-order LC resonator, a second-order LC resonator, and a second-order LC resonator in the multi-order transmitting filter, and coupling M01, M04, M12, M23, M14, M45, M56 between 7 LC resonators is implemented by a varactor and a high impedance microstrip line, and the hybrid coupling thereof not only introduces more transmission zeros for the circuit, but also supports a mechanism of space-time modulation, thereby providing a basic framework for implementing a space-time modulation based magnetic loop circulator. Three ports: the antenna end is 1 port, the receiving end is 2 ports, the transmitting end is 3 ports, three external coupling capacitors J0, J1 and J2 are respectively introduced into the antenna end, the receiving end and the transmitting end, and the external coupling capacitors J0, J1 and J2 are varactors so as to complete the matching effect on the external ports. In the application, when the time domain signals at M01, M04 and M14 modulate the nonlinear capacitance loaded by the time domain signals, the time reversibility of the loop is broken, and the nonreciprocal effect is formed, so that the design of the circulator is completed. The high-power signal generated by the transmitting end flows to the receiving end, the signal flow is S23 (J2-R6-R5-R4-M14-R1-R2-R3-J1), firstly, the signal flow generates an inherent isolation degree from transmitting to receiving under the effect of space-time modulation, and the original isolation is increased again due to the complexity and loss of a circuit because of the transmission coupling of the signal S23 among a plurality of resonators, so that the isolation degree based on a circulator architecture is increased for the first time, and the isolation degree is obviously enhanced to 26dB.

For a high-power transmitting end signal, the self-interference cancellation path 1 and the self-interference cancellation path 2 are introduced into a filtering circulator circuit structure, the self-interference cancellation path 1 is grafted between the resonators R3 and R6, the self-interference cancellation path 2 is grafted between the resonators R2 and R5, and two different paths respectively correspond to two different working frequency points f1 and f2.

First, the two paths of signals are extremely weak, and have two variables, namely the amplitude and phase of the signals, in order to cancel the original signal S23 in the loop by using the two paths of signals, two conditions must be satisfied: (1) the amplitude of the signal of the self-interference cancellation path 1 at the frequency point f1 must be the same as the amplitude of the signal S23 at the frequency point f 1; (2) the phase of the signal of the self-interference cancellation path 1 at the frequency point f1 must be 180 degrees different from the phase of the signal of S23 at the frequency point f 1; when the signal of the self-interference cancellation path 1 satisfies these two conditions, the signal of the f1 frequency point in the S23 signal will be cancelled, and similarly, the same principle is adopted for the self-interference cancellation path 2 at the frequency point f2. When the signals of the two self-interference cancellation paths satisfy the relationship of the signals at f1 and f2, the signals at the two frequency points of f1 and f2 are cancelled by the signal S23, so that a high isolation effect with two cancellation points is formed. It is noted that, since the isolation degree generated by the space-time modulation is already about 26dB, the signal amplitudes of the two corresponding self-interference cancellation paths are extremely small, so that the introduction of the two self-interference cancellation path circuits has no or little influence on other performances of the overall architecture of the filter circulator, which can be demonstrated by the subsequent test results.

As shown in fig. 2, the circuit structure of the self-interference cancellation path is specifically: the two self-interference cancellation path circuits realize the amplitude regulation and control of self-interference cancellation signals through four varactors of a loaded external capacitor CkBs, ckBs, ckBss, ckBss; the phase of the two self-interference cancellation signals is regulated and controlled by controlling the grounded varactor CBs, CBs, CBss, CBss, and the amplitude-phase control circuit based on the non-resonance point has flexible reconfigurable performance, can flexibly regulate and control the phase of the circuit signal, and supports arbitrary regulation of 0-360 degrees so as to meet the requirement of canceling any phase of the signal in S23. In the same way, because of the high reconfigurable performance, the working center frequency point also has an adjusting function, and the performance of high isolation can be reconfigured, so that the performance of high isolation can be switched between broadband isolation (41 dB isolation with the bandwidth of 28 MHz) and narrowband isolation (isolation with the peak value exceeding 63 dB) at will, thereby realizing an adjustable isolation effect and meeting different communication requirements.

The application is realized by combining a micro-strip technology based on a varactor, the substrate material is Rogowski 6010, and the thickness is 1.27mm. The capacitors of the resonators R0, R1, R2, R3, R4, R5 and R6 are all realized by varactors to meet the adjustment of resonant frequency, the coupling capacitors are also realized by varactors, varactors of MA46202 type are selected, and varactors J0, J1 and J2 are varactors of MA46203 type.

And CkBs in the self-interference cancellation path 1 and the self-interference cancellation path 2 circuits adopt varactors of the model MAVR-01020-1411. CBs and CBss are varactors of MA46204 type, wherein the inductor is a 2.2nH patch inductor. The resistor is used for isolating DC and radio frequency signals, a large resistor of 100Kohm is selected, and 100PF isolation capacitors are further arranged in the circuit structures of the self-interference cancellation path 1 and the self-interference cancellation path 2.

In the embodiment of the application, the bias states of all the varactors are controlled by the externally applied bias voltage, and the capacitance value of the varactors can be changed by adjusting the magnitude of the externally applied bias voltage, so that the flexible reconstruction of the filter performance is realized. Specifically, 2 varactors CkBs and 2 varactors CkBs are used for controlling the amplitude of the self-interference signal, 2 varactors CBs and 2 varactors CBss are used for controlling the phase of the self-interference signal, and the 8 varactors can be flexibly controlled by only 4 bias voltages due to the symmetry of the self-cancellation circuit structure.

Fig. 3 shows a test setup of the present application, fig. 7 (a) and fig. 7 (b) are physical diagrams of a circuit structure of the present application, a signal generator is used to generate a modulation signal and the modulation signal is divided into 4 paths of signals by a power divider, wherein a DC control voltage board is used to control bias voltages of all varactors in the circuit structure of the present application, and a computer is used to control a voltage control board to realize bias voltage requirements of different varactors.

In the application, the proposed reconfigurable isolation effect has three different cases, namely:

case1: isolation due to space-time modulation and circuit topology introduction;

case2: the high isolation of the broadband is realized due to the influence of the self-interference cancellation circuit;

case3: due to the influence of the self-interference cancellation circuit, the narrow-band high isolation is realized;

the graph of fig. 4 shows the S-parameter test effect of three different frequency signals, in particular: fig. 4 (a) shows the filter passband from antenna end to receiver end, and fig. 4 (c) shows the filter passband from transmitter end to antenna end; fig. 4 (b) shows the filtering isolation effect from the receiving end to the antenna end, and fig. 4 (d) shows the filtering isolation effect from the antenna end to the transmitting end;

fig. 5 shows the corresponding S-parameter test effect, in particular: fig. 5 (a), 5 (b) and 5 (c) show port echo performance at the antenna end, the receiving end and the transmitting end;

fig. 6 shows the corresponding S-parameter test effect, in particular: fig. 6 (a) shows the path from the receiving end to the transmitting end, and this index is not practical because in practice the receiving end is not signal-inputted; mainly, fig. 6 (b) shows the isolation from the transmitting end to the receiving end, which is higher than the other two isolation characteristics under the effect of no self-interference cancellation circuit, namely, two isolation effects from the receiving end to the antenna end and from the antenna end to the transmitting end in fig. 4 (b) and 4 (d), which is the first improvement of the isolation due to the design of the circuit structure; FIG. 6 (c) shows the isolation from the transmitting end to the receiving end, which is a wideband high isolation under the action of a self-interference cancellation circuit operating at two different frequency points; fig. 6 (d) shows the isolation from the transmitting end to the receiving end, which is a narrow-band high isolation under the action of the self-interference cancellation circuit operating at two identical frequency points; showing the highly reconfigurable characteristic of the isolation, and the reconfigurable characteristic of the center frequency.

The application is based on the self-interference cancellation technology, by controlling the amplitude and the phase of the self-interference cancellation circuit (self-interference cancellation path 1 and self-interference cancellation path 2), the self-interference signal cancels the introduced signal, thereby realizing high isolation, and the working frequency of the cancellation point of the self-interference cancellation circuit can be reconfigured due to the reconfigurability of the self-interference cancellation circuit, thereby completing the reconfigurability of the position of the cancellation point and realizing the reconfigurability isolation performance _。 Specifically, the filter circulator of the present application may be divided into the following advantages: (1) based on the self-interference cancellation technology, the high isolation between the transmitting end and the receiving end is realized, and a microwave filter circulator with reconfigurable isolation is designed and realized; (2) the amplitude-phase control circuit generates self-interference cancellation signals, namely a self-interference cancellation path 1 and a self-interference cancellation path 2, the signals of the circuit can be reconstructed, on the basis of realizing high isolation, the reconfigurable characteristic of the isolation can be realized by adjusting the amplitude-phase control circuit, the flexible and variable isolation performance can be realized, and the working mode of switching between broadband isolation and narrowband isolation can be completed; (3) the filter is integrated in a circulator and the center frequency of the filter is reconfigurable, thereby producing a reconfigurable filter circulator with a third order filter response, the center frequency of which is freely adjustable.

The application provides a non-resonance point-based amplitude-phase control circuit which is applied to a self-interference cancellation filter circulator, so that high isolation between a transmitting end and a receiving end and reconfigurable isolation performance are realized, the performance of a receiving and transmitting component in a full duplex system is flexibly regulated and changed, and the multifunctional, switchable and strong reconfigurable performance of the system is greatly improved.

In the description of embodiments of the present application, the terms "first," "second," "third," "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", "a third" and a fourth "may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

In describing embodiments of the present application, it should be noted that the terms "mounted," "connected," and "assembled" are to be construed broadly, as they may be fixedly connected, detachably connected, or integrally connected, unless otherwise specifically indicated and defined; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.

In the description of embodiments of the application, a particular feature, structure, material, or characteristic may be combined in any suitable manner in one or more embodiments or examples.

In the description of embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, meaning that three relationships may exist, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The reconfigurable microwave filter circulator with the self-interference isolation adjustable function is characterized by comprising the following components: an antenna end, a transmitting end and a receiving end,

2. The reconfigurable microwave filter circulator with the self-interference isolation adjustable function according to claim 1, wherein the multi-order transmitting filter and the multi-order receiving filter are both three-order, namely the multi-order receiving filter comprises LC resonators R1, R2 and R3, the multi-order transmitting filter comprises LC resonators R4, R5 and R6,

3. A reconfigurable microwave filter circulator with self-interference isolation adjustable function according to claim 2, wherein: three external coupling capacitors J0, J1 and J2 are respectively introduced into the antenna end, the receiving end and the transmitting end, and the coupling capacitors J0, J1 and J2 are varactors and are used for matching with external ports.

4. A reconfigurable microwave filter circulator with self-interference isolation adjustable function according to claim 2, wherein: a self-interference cancellation path 1 is grafted between the R2 and the R5, the path signal corresponds to a frequency point f1, a self-interference cancellation path 2 is grafted between the R3 and the R6, the path signal corresponds to a frequency point f2, the self-interference cancellation path 1 counteracts a signal S23 at the frequency point f1, and the self-interference cancellation path 2 counteracts the signal S23 at the frequency point f2 to obtain high isolation performance with two counteraction points.

5. The reconfigurable microwave filter circulator with self-interference isolation adjustable function of claim 4, wherein: the self-interference cancellation path 1\self-interference cancellation path 2 is reconfigurable in amplitude and phase at the frequency point f 1\frequency point f2, the signal S23 is cancelled by controlling the amplitude and phase of the self-interference cancellation path 1\self-interference cancellation path 2 at the frequency point f 1\frequency point f2, the high isolation performance is realized, the phases of the self-interference cancellation path 1 and the self-interference cancellation path 2 are adjustable, the working center frequency point is adjustable, the high isolation performance can be switched between broadband isolation and narrowband isolation, and the flexible reconfigurable isolation performance is realized.

6. The reconfigurable microwave filter circulator with self-interference isolation adjustable function of claim 5, wherein: the self-interference cancellation path 1 cancels the signal S23 at the frequency point f1 specifically:

7. The reconfigurable microwave filter circulator with self-interference isolation adjustable function of claim 6, wherein: the self-interference cancellation path 1 comprises 2 external varactors CkBs, 2 parallel NRNs and 1 resistor, wherein the 2 varactors CkBs are connected at two ends of the resistor, one end of the NRNs is connected between the resistor and the varactors CkBs, the other end of the NRNs is grounded, and the self-interference cancellation path 1 is respectively connected with LC resonators R3 and R6 through the 2 varactors CkBs;

8. The reconfigurable microwave filter circulator with self-interference isolation adjustable function of claim 7, wherein: the NRN of the self-interference cancellation path 1 comprises an inductor and a varactor CBs which are connected in parallel, one ends of the inductor and the varactor CBs are grounded, one ends of the inductor and the varactor CBs are connected with a varactor CkBs, the self-interference cancellation signal is subjected to phase regulation by controlling bias voltages loaded on 2 varactors CBs, the phase is controlled to be adjusted at 0-360 degrees, and the phase requirement of cancellation of the signal S23 at a frequency point f1 is met.

9. The reconfigurable microwave filter circulator with the self-interference isolation adjustable function according to claim 6, wherein the self-interference cancellation path 2 comprises 2 varactors ckbs, 2 parallel NRNs and 1 resistor, the 2 varactors ckbs are connected at two ends of the resistor, one end of the NRN is connected between the resistor and the varactors ckbs, the other end is grounded, and the self-interference cancellation path 2 is connected to LC resonators R2 and R5 through the 2 varactors ckbs, respectively;

10. The reconfigurable microwave filter circulator with self-interference isolation adjustable function of claim 9, wherein: the NRN of the self-interference cancellation path 2 comprises an inductor and a varactor CBss which are connected in parallel, one ends of the inductor and the varactor CBss are grounded, one ends of the inductor and the varactor CBss are connected with the varactor CkBss, the self-interference cancellation signal is subjected to phase regulation by controlling bias voltage loaded on 2 varactors CBss, the phase is controlled to be adjusted at 0-360 degrees, and the phase requirement of cancellation of the signal S23 at a frequency point f2 is met.