Reconfigurable microwave filtering circulator with self-interference isolation adjustability
By introducing a multi-stage filter and a self-interference cancellation path into the microwave filter circulator, and utilizing the hybrid coupling of varactor diodes and high-impedance microstrip lines, the amplitude and phase of the self-interference signal can be controlled, solving the self-interference problem in the full-duplex system and improving the reconfigurability of isolation and system performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF ELECTRONICS SCI & TECH OF CHINA
- Filing Date
- 2023-08-31
- Publication Date
- 2026-07-31
AI Technical Summary
Existing self-interference cancellation techniques cannot achieve high isolation between the transmitter and receiver, and the isolation is not reconfigurable, making it difficult to solve the self-interference problem in full-duplex systems.
Design a reconfigurable microwave filter circulator with adjustable self-interference isolation. By introducing multi-stage filters and self-interference cancellation paths into the circulator, and utilizing the hybrid coupling of varactor diodes and high-impedance microstrip lines, the amplitude and phase of the signal can be adjusted, multiple transmission zeros can be formed, and time-limited control can be supported, achieving high isolation and reconfigurability.
It achieves high isolation between the transmitter and receiver, and the isolation can be flexibly switched between broadband and narrowband, which enhances the isolation performance of the full-duplex system and reduces the system complexity.
Smart Images
Figure CN117175171B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wireless communication system technology, and in particular to a reconfigurable microwave filter circulator with adjustable self-interference isolation. Background Technology
[0002] In modern wireless communication technology, full-duplex systems are widely studied by scholars because they can support simultaneous uplink and downlink operation at the same frequency, thus expanding channel capacity. However, a major problem with full-duplex systems is that high-power signals from the transmitter can leak into the receiver circuitry, significantly impacting the overall communication system. Therefore, achieving high isolation between the transmitter and receiver is the main goal for solving this type of self-interference problem. Self-interference signals in full-duplex systems include: ① high-power signal reflections at the antenna; ② self-interference signals generated by external factors and multipath effects; ③ high-power signals leaked from the transmitter to the receiver.
[0003] In the reported literature, to solve this type of self-interference problem, most solutions employ self-interference cancellation techniques in devices such as circulators, often using digital signal processing methods such as DSPs to eliminate self-interference signals and achieve high isolation. However, the construction of digital modules significantly complicates the framework of the RF transceiver system, and its operation is complex. Furthermore, the integration of digital signal modules with RF analog signal transceiver circuits presents another challenge. Introducing redundant DACs and ADCs further increases system complexity. Moreover, the reported self-interference cancellation techniques do not support high reconfigurability of isolation. To achieve high isolation between the transmitter and receiver in the RF transceiver components and make the isolation reconfigurable, a reconfigurable microwave filter circulator with adjustable self-interference isolation is required. Summary of the Invention
[0004] The purpose of this invention is to provide a reconfigurable microwave filter circulator with adjustable self-interference isolation. This circulator allows for free adjustment of the isolation between the transmitter and receiver. Based on self-interference cancellation technology, by controlling the amplitude and phase of the self-interference cancellation path circuit, the introduced signal is eliminated by the self-interference signal, thereby achieving high isolation. Furthermore, due to the reconfigurability of the self-interference cancellation path circuit, the operating frequency of its cancellation point is reconfigurable, enabling reconfigurable positioning of the cancellation point and achieving reconfigurable isolation. This addresses the problem that existing self-interference cancellation technologies cannot support highly reconfigurable isolation.
[0005] To address the aforementioned problems in the prior art, this invention provides a reconfigurable microwave filter circulator with adjustable self-interference isolation, comprising: an antenna end, a transmitting end, and a receiving end.
[0006] A multi-stage transmission filter is connected between the antenna end and the transmitter end. The multi-stage transmission filter includes multiple LC resonators arranged in parallel. One end of the multiple LC resonators is grounded, and the other end of the multiple LC resonators is coupled through a varactor diode and a high-impedance microstrip line.
[0007] A multi-stage receiving filter is connected between the antenna end and the receiving end. The multi-stage receiving filter includes multiple LC resonators arranged in parallel. One end of the multiple LC resonators is grounded, and the other end of the multiple LC resonators is coupled through a varactor diode and a high-impedance microstrip line.
[0008] The multi-stage transmit filter and the multi-stage receive filter are both connected to the antenna end, and an LC resonator R0 is connected in parallel at the connection point of the three. One end of the LC resonator R0 is connected to the antenna end, and the other end is grounded.
[0009] The LC resonator R0, the first-order LC resonator of the multi-order transmit filter, and the first-order LC resonator of the multi-order receive filter are all coupled in pairs through varactor diodes and high-impedance microstrip lines to form an overall filter circulator architecture with multiple transmission zeros and support time-limited control.
[0010] The signal generated by the transmitting end is transmitted and coupled through multiple LC resonators to the receiving end, i.e., signal S23, which is isolated.
[0011] Furthermore, both the multi-order transmitting filter and the multi-order receiving filter are third-order; that is, the multi-order receiving filter includes LC resonators R1, R2, and R3, and the multi-order transmitting filter includes LC resonators R4, R5, and R6.
[0012] The coupling between LC resonator R0 and LC resonator R1 is M01, the coupling between LC resonator R0 and LC resonator R4 is M04, and the coupling between LC resonator R1 and LC resonator R4 is M14.
[0013] The coupling between LC resonator R1 and LC resonator R2 is M12, and the coupling between LC resonator R2 and LC resonator R3 is M23.
[0014] The coupling between LC resonators R4 and R5 is M45, and the coupling between LC resonators R5 and R6 is M56.
[0015] M01, M04, M14, M12, M23, M45, and M56 are parallel varactor diodes and high-impedance microstrip lines, providing multiple transmission zeros for the filter circulator and supporting time-limited control to eliminate magnetic bias and form a non-magnetic filter circulator.
[0016] Furthermore, three external coupling capacitors J0, J1, and J2 are introduced at the antenna end, receiver end, and transmitter end, respectively. The coupling capacitors J0, J1, and J2 are varactor diodes used to match the external ports.
[0017] Furthermore, a self-interference cancellation path 1 is grafted between R2 and R5, with the signal corresponding to frequency point f1. A self-interference cancellation path 2 is grafted between R3 and R6, with the signal corresponding to frequency point f2. The self-interference cancellation path 1 cancels the signal S23 at frequency point f1, and the self-interference cancellation path 2 cancels the signal S23 at frequency point f2, resulting in high isolation performance with two cancellation points.
[0018] Furthermore, the amplitude and phase of the self-interference cancellation path 1 and self-interference cancellation path 2 at frequency points f1 and f2 are reconfigurable. By controlling the amplitude and phase of the self-interference cancellation path 1 and self-interference cancellation path 2 at frequency points f1 and f2, signal S23 is canceled, achieving high isolation performance. The phases of the self-interference cancellation path 1 and self-interference cancellation path 2 are adjustable, and their operating center frequency is adjustable, allowing the high isolation performance to switch between broadband isolation and narrowband isolation, achieving flexible reconfigurable isolation performance.
[0019] Furthermore, the self-interference cancellation path 1 cancels out signal S23 at frequency f1 specifically as follows:
[0020] The amplitude of the signal controlling the self-interference cancellation path 1 at frequency point f1 is the same as the amplitude of the S23 signal at frequency point f1, and the phase of the signal controlling the self-interference cancellation path 1 at frequency point f1 is 180 degrees different from the phase of the S23 signal at frequency point f1.
[0021] Similarly, the self-interference cancellation path 2 cancels out signal S23 at frequency point f2 specifically as follows:
[0022] The amplitude of the signal controlling the self-interference cancellation path 2 at frequency point f2 is the same as the amplitude of the S23 signal at frequency point f2, and the phase of the signal controlling the self-interference cancellation path 2 at frequency point f2 is 180 degrees different from the phase of the S23 signal at frequency point f2.
[0023] Furthermore, the self-interference cancellation path 1 includes two external varactor diodes CkBs, two parallel NRNs, and one resistor. The two varactor diodes CkBs are connected across the two ends of the resistor. One end of the NRN is connected between the resistor and the varactor diodes CkBs, and the other end is grounded. The self-interference cancellation path 1 is connected to the LC resonators R3 and R6 through the two varactor diodes CkBs respectively.
[0024] The amplitude of the self-interference cancellation signal is modulated by controlling the bias voltage applied to the two varactor diodes CkBs.
[0025] Furthermore, the NRN of the self-interference cancellation path 1 includes an inductor and a varactor diode CBs connected in parallel. One end of the inductor and the varactor diode CBs is grounded, and the other end of the inductor and the varactor diode CBs is connected to a varactor diode CkBs. By controlling the bias voltage applied to the two varactor diodes CBs, the phase of the self-interference cancellation signal is modulated, and the phase is controlled to be adjusted between 0 and 360 degrees to meet the phase requirement of signal S23 canceling at frequency point f1.
[0026] Furthermore, the self-interference cancellation path 2 includes two varactor diodes CkBss, two parallel NRNs, and one resistor. The two varactor diodes CkBss are connected across the two ends of the resistor. One end of the NRN is connected between the resistor and the varactor diodes CkBss, and the other end is grounded. The self-interference cancellation path 2 is connected to the LC resonators R2 and R5 respectively through the two varactor diodes CkBss.
[0027] The amplitude of the self-interference cancellation signal is modulated by controlling the bias voltage applied to the two varactor diodes CkBss.
[0028] Furthermore, the NRN of the self-interference cancellation path 2 includes an inductor and a varactor diode CBss connected in parallel. One end of the inductor and the varactor diode CBss is grounded, and the other end of the inductor and the varactor diode CBss is connected to a varactor diode CkBss. By controlling the bias voltage applied to the two varactor diodes CBss, the phase of the self-interference cancellation signal is modulated, and the phase is controlled to be adjusted between 0 and 360 degrees to meet the phase requirement of signal S23 canceling at frequency point f2.
[0029] The beneficial effects of this invention are reflected in:
[0030] This invention is a reconfigurable microwave filter circulator with adjustable self-interference isolation. The seven parallel LC resonators are coupled through varactor diodes and high-impedance microstrip lines, which not only introduces more transmission zeros into the circuit structure, but also supports time-limited control, realizing a microwave non-magnetic reconfigurable filter circulator. The circulator architecture of seven LC resonators makes the original signal path from the transmitter to the receiver longer, and the isolation is enhanced for the first time.
[0031] This invention relates to a reconfigurable microwave filter circulator with adjustable self-interference isolation. Based on self-interference cancellation technology, two additional self-interference cancellation path signals are introduced to cancel out the original isolation signal. The introduction of these two cancellation points further enhances isolation. Furthermore, since the introduced additional signal paths are weakly coupled, they do not affect other performance characteristics of the filter circulator circuit.
[0032] This invention is a reconfigurable microwave filter circulator with adjustable self-interference isolation. It is the first to propose the application of a non-resonant phase-shifting circuit in a self-interference cancellation circulator. The amplitude can be adjusted by controlling the coupling varactor diode loaded outside the circuit, and the phase can be adjusted by adjusting the grounded varactor diode loaded. The center frequency can also be adjusted, so that the high isolation performance can be arbitrarily switched between broadband isolation and narrowband isolation, achieving flexible reconfigurable isolation performance.
[0033] This invention is a reconfigurable microwave filter circulator with adjustable self-interference isolation. The circulator architecture realizes a filter circulator with a third-order filtering response and multiple transmission zeros. Due to the reconfigurability of the center frequency of the LC resonator, the center frequency of the circulator is also reconfigurable, realizing a flexible operating mode. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the overall circuit structure of the present invention;
[0035] Figure 2 A schematic diagram of the circuit structure for the self-interference cancellation path;
[0036] Figure 3 This is a schematic diagram of the circuit test of the present invention;
[0037] Figure 4 These are the S-parameter passband test results of this invention;
[0038] Figure 5 The results of the S-parameter return loss test of this invention;
[0039] Figure 6 These are the S-parameter isolation test results of this invention;
[0040] Figures 7(a) and 7(b) show the front and back of the physical object of the present invention, respectively. Detailed Implementation
[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0042] Example 1:
[0043] Reference Figure 1 This invention is a reconfigurable microwave filter circulator with adjustable self-interference isolation, comprising: an antenna end, a transmitting end, and a receiving end.
[0044] A multi-stage transmission filter is connected between the antenna end and the transmitter end. The multi-stage transmission filter includes multiple LC resonators arranged in parallel. One end of the multiple LC resonators is grounded, and the other end of the multiple LC resonators is coupled through a varactor diode and a high-impedance microstrip line.
[0045] A multi-stage receiving filter is connected between the antenna end and the receiving end. The multi-stage receiving filter includes multiple LC resonators arranged in parallel. One end of the multiple LC resonators is grounded, and the other end of the multiple LC resonators is coupled through a varactor diode and a high-impedance microstrip line.
[0046] The multi-stage transmit filter and the multi-stage receive filter are both connected to the antenna end, and an LC resonator R0 is connected in parallel at the connection point of the three. One end of the LC resonator R0 is connected to the antenna end, and the other end is grounded.
[0047] The LC resonator R0, the first-order LC resonator of the multi-order transmit filter, and the first-order LC resonator of the multi-order receive filter are all coupled in pairs through varactor diodes and high-impedance microstrip lines to form an overall filter circulator architecture with multiple transmission zeros and support time-limited control.
[0048] The signal generated by the transmitting end is transmitted and coupled through multiple LC resonators to the receiving end, i.e., signal S23, which is isolated.
[0049] like Figure 1The diagram shows the overall architecture of the filter circulator proposed in this invention. It consists of seven parallel LC resonators R0, R1, R2, R3, R4, R5, and R6 forming the main framework. R1, R2, and R3 are the first-order, second-order, and second-order LC resonators in the multi-order receive filter, respectively. R4, R5, and R6 are the first-order, second-order, and second-order LC resonators in the multi-order transmit filter, respectively. The couplings M01, M04, M12, M23, M14, M45, and M56 between the seven LC resonators are achieved using varactor diodes and high-impedance microstrip lines. This hybrid coupling not only introduces more transmission zeros to the circuit but also supports a time-spaced mechanism, providing a basic framework for realizing a time-spaced, non-magnetic circulator. The circuit has three ports: port 1 for the antenna, port 2 for the receiver, and port 3 for the transmitter. Three external coupling capacitors J0, J1, and J2 are introduced at the antenna, receiver, and transmitter ends, respectively. These external coupling capacitors are varactor diodes to match the external ports. In this invention, when the time-domain signals at M01, M04, and M14 modulate the nonlinear capacitors, the time reversal property of the loop is broken, and a non-reciprocal effect is formed, thus completing the circulator design. The high-power signal generated at the transmitter flows to the receiver, passing through S23 (J2-R6-R5-R4-M14-R1-R2-R3-J1). Firstly, due to the time-space regulation, an inherent transmit-to-receive isolation is achieved. Secondly, due to the transmission coupling of signal S23 between multiple resonators, the original isolation increases again due to circuit complexity and losses, achieving the first increase in isolation based on the circulator architecture, significantly enhancing the isolation to 26dB.
[0050] For high-power transmitting signals, this invention introduces self-interference cancellation path 1 and self-interference cancellation path 2 in the filter circulator circuit structure. Self-interference cancellation path 1 is connected between resonators R3 and R6, and self-interference cancellation path 2 is connected between resonators R2 and R5. The two different paths correspond to two different operating frequencies f1 and f2, respectively.
[0051] First, the signals from these two paths are extremely weak, possessing only two variables: amplitude and phase. To use these two path signals to cancel the original signal S23 in the loop, two conditions must be met: ① The amplitude of the signal from self-cancellation path 1 at frequency f1 must be the same as the amplitude of the S23 signal at frequency f1; ② The phase of the signal from self-cancellation path 1 at frequency f1 must differ from the phase of the S23 signal at frequency f1 by 180 degrees. When the signal from self-cancellation path 1 meets these two conditions, the signal at frequency f1 in the S23 signal will be canceled. Similarly, the same principle applies to self-cancellation path 2 at frequency f2. When the signals from the two self-cancellation paths satisfy the above signal relationship at f1 and f2, the signal S23 at both frequencies f1 and f2 will be canceled, thus creating a high isolation effect with two cancellation points. It is worth noting that since the isolation generated by the time-limited control is already around 26dB, the signal amplitudes of the two self-interference cancellation paths are also extremely small. Therefore, the introduction of the two self-interference cancellation path circuits has no impact on the other performance of the overall filter circulator architecture, or rather, the impact is minimal. This can also be proven by subsequent test results.
[0052] like Figure 2 The diagram shows the circuit structure of the self-interference cancellation path. Specifically, the two self-interference cancellation path circuits use four varactor diodes (CkBs, CkBss, CkBss, CkBss) with externally loaded capacitors to achieve amplitude modulation of the self-interference cancellation signal. The phase of the two self-interference cancellation signals is controlled by grounded varactor diodes (CBs, CBss, CBss, CBss). This amplitude-phase control circuit based on a non-resonant point has flexible reconfigurability, allowing for flexible adjustment of the circuit signal phase and supporting arbitrary adjustment from 0 to 360 degrees to meet the requirement of canceling any phase of the signal in S23. Similarly, due to its high reconfigurability, its operating center frequency is also adjustable, and the high isolation performance can be reconfigured, allowing the high isolation performance to switch arbitrarily between broadband isolation (41dB isolation with a bandwidth of 28MHz) and narrowband isolation (isolation exceeding 63dB peak value), thus achieving an adjustable isolation effect to meet different communication needs.
[0053] This invention employs a combination of varactor diodes and microstrip technology. The substrate material is Rogers 6010 with a thickness of 1.27 mm. The capacitances of the resonators R0, R1, R2, R3, R4, R5, and R6 are all implemented using varactor diodes to achieve adjustable resonant frequencies. The coupling capacitors are also implemented using varactor diodes, specifically the MA46202 model. Varactor diodes J0, J1, and J2 are MA46203 model varactor diodes.
[0054] In the self-interference cancellation path 1 and self-interference cancellation path 2 circuits, CkBs and CkBss are MAVR-011020-1411 varactor diodes. CBs and CBss are MA46204 varactor diodes. A 2.2nH surface-mount inductor is used. Resistors are used to isolate DC and RF signals, and large 100Kohm resistors are selected. A 100pF isolation capacitor is also included in the circuit structure of self-interference cancellation path 1 and self-interference cancellation path 2.
[0055] In this embodiment of the invention, the bias state of all varactor diodes is controlled by an external bias voltage. By adjusting the magnitude of the external bias voltage, the capacitance value of the varactor diodes can be changed, thereby achieving flexible reconfiguration of the filter performance. Specifically, two varactor diodes CkBs and two varactor diodes CkBss are used to control the amplitude of the self-interference signal, and two varactor diodes CBs and two varactor diodes CBss are used to control the phase of the self-interference signal. Due to the symmetry of the self-cancellation circuit structure, the above eight varactor diodes only require four bias voltages to achieve flexible control.
[0056] Figure 3 The test setup of the present invention is shown. Figures 7(a) and 7(b) are physical diagrams of the circuit structure of the present invention. A signal generator generates a modulated signal and divides it into four signals through a power divider. The DC control voltage board controls the bias voltage of all varactor diodes in the circuit structure of the present invention. The computer controls the voltage control board to achieve the bias voltage requirements of different varactor diodes.
[0057] In this invention, the proposed reconfigurable isolation effect has three different cases, namely:
[0058] Case 1: Isolation introduced by time-limited control and circuit topology;
[0059] Case 2: Wideband high isolation is achieved due to the influence of the self-interference cancellation circuit;
[0060] Case 3: Narrowband high isolation is achieved due to the influence of the self-interference cancellation circuit;
[0061] Figure 4 The graph shows the S-parameter test results for three different frequency signals, specifically: Figure 4 (a) shows the filtered passband from the antenna end to the receiver end. Figure 4 (c) Shows the filter passband from the transmitter to the antenna; Figure 4 (b) demonstrates the filtering isolation effect from the receiver to the antenna. Figure 4 (d) demonstrates the filtering isolation effect from the antenna end to the transmitter end;
[0062] Figure 5 The corresponding S-parameter test results are shown, specifically: Figure 5 (a), Figure 5 (b) and Figure 5 (c) The port echo performance of the antenna, receiver, and transmitter is shown;
[0063] Figure 6 The corresponding S-parameter test results are shown, specifically: Figure 6 (a) illustrates the path from the receiver to the transmitter. However, since there is no signal input at the receiver in practice, this indicator is meaningless. The main point is... Figure 6 (b) demonstrates the isolation between the transmitter and receiver, which, without the self-interference cancellation circuitry, is significantly higher than the other two isolation characteristics. Figure 4 (b) and Figure 4 (d) The two isolation effects between the receiver and the antenna, and between the antenna and the transmitter, are the first improvement in isolation brought about by the design of the circuit structure. Figure 6 (c) demonstrates the isolation from the transmitter to the receiver, with broadband high isolation under the action of self-interference cancellation circuits operating at two different frequencies; Figure 6 (d) shows the isolation from the transmitter to the receiver, and its high isolation in the narrowband under the action of the self-interference cancellation circuit operating at two identical frequencies; it shows the highly reconfigurable characteristics of the isolation and the reconfigurable characteristics of the center frequency.
[0064] This invention is based on self-interference cancellation technology. By controlling the amplitude and phase of the self-interference cancellation circuit (self-interference cancellation path 1 and self-interference cancellation path 2), the self-interference signal eliminates the introduced signal, thereby achieving high isolation. Furthermore, due to the reconfigurability of the self-interference cancellation circuit, the operating frequency of its cancellation point can be reconfigured, thus enabling reconfigurable positioning of the cancellation point and achieving reconfigurable isolation performance. 。 Specifically, the filter circulator of this invention has the following advantages: ① It achieves high isolation between the transmitter and receiver based on self-interference cancellation technology, and designs and implements a microwave filter circulator with reconfigurable isolation; ② It proposes an amplitude and phase control circuit for generating self-interference cancellation signals, namely self-interference cancellation path 1 and self-interference cancellation path 2, and the signal of this circuit is reconfigurable. On the basis of achieving high isolation, the reconfigurable isolation characteristic can be achieved by adjusting the amplitude and phase control circuit, realizing flexible and variable isolation performance, and enabling switching between broadband isolation and narrowband isolation operating modes; ③ It integrates the filter into the circulator, and the center frequency of the filter is reconfigurable, thereby producing a reconfigurable filter circulator with a third-order filtering response, whose center frequency can be freely adjusted.
[0065] This invention proposes a non-resonant point amplitude and phase control circuit, which is applied to a self-interference cancellation filter circulator to achieve high isolation between the transmitter and receiver, as well as reconfigurable isolation performance. It allows for flexible adjustment and modification of the performance of the transceiver components in a full-duplex system, greatly improving the system's multifunctionality, switchability, and strong reconfigurability.
[0066] In the description of embodiments of the present invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first," "second," "third," or "fourth" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise stated, "a plurality of" means two or more.
[0067] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "assembly" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.
[0068] In the description of embodiments of the present invention, specific features, structures, materials or characteristics may be combined in any suitable manner in one or more embodiments or examples.
[0069] In the description of embodiments of the present invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0070] Although embodiments of the invention 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 to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A reconfigurable microwave filter circulator with adjustable self-interference isolation, characterized in that, It has: an antenna end, a transmitting end, and a receiving end. A multi-stage transmission filter is connected between the antenna end and the transmitter end. The multi-stage transmission filter includes multiple LC resonators arranged in parallel. One end of the multiple LC resonators is grounded, and the other end of the multiple LC resonators is coupled through a varactor diode and a high-impedance microstrip line. A multi-stage receiving filter is connected between the antenna end and the receiving end. The multi-stage receiving filter includes multiple LC resonators arranged in parallel. One end of the multiple LC resonators is grounded, and the other end of the multiple LC resonators is coupled through a varactor diode and a high-impedance microstrip line. The multi-stage transmit filter and the multi-stage receive filter are both connected to the antenna end, and an LC resonator R0 is connected in parallel at the connection point of the three. One end of the LC resonator R0 is connected to the antenna end, and the other end is grounded. The LC resonator R0, the first-order LC resonator of the multi-order transmit filter, and the first-order LC resonator of the multi-order receive filter are all coupled in pairs through varactor diodes and high-impedance microstrip lines to form an overall filter circulator architecture with multiple transmission zeros and support time-limited control. The signal generated by the transmitting end is transmitted and coupled through multiple LC resonators to the receiving end, i.e., signal S23, which is isolated.
2. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 1, characterized in that, Both the multi-order transmit filter and the multi-order receive filter are third-order; that is, the multi-order receive filter includes LC resonators R1, R2, and R3, and the multi-order transmit filter includes LC resonators R4, R5, and R6. The coupling between LC resonator R0 and LC resonator R1 is M01, the coupling between LC resonator R0 and LC resonator R4 is M04, and the coupling between LC resonator R1 and LC resonator R4 is M14. The coupling between LC resonator R1 and LC resonator R2 is M12, and the coupling between LC resonator R2 and LC resonator R3 is M23. The coupling between LC resonators R4 and R5 is M45, and the coupling between LC resonators R5 and R6 is M56. M01, M04, M14, M12, M23, M45, and M56 are parallel varactor diodes and high-impedance microstrip lines, providing multiple transmission zeros for the filter circulator and supporting time-limited control to eliminate magnetic bias and form a non-magnetic filter circulator.
3. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 2, characterized in that: Three external coupling capacitors J0, J1, and J2 are introduced at the antenna end, receiver end, and transmitter end, respectively. The coupling capacitors J0, J1, and J2 are varactor diodes used to match the external ports.
4. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 2, characterized in that: A self-interference cancellation path 1 is grafted between R2 and R5, with the signal corresponding to frequency point f1. A self-interference cancellation path 2 is grafted between R3 and R6, with the signal corresponding to frequency point f2. The self-interference cancellation path 1 cancels the signal S23 at frequency point f1, and the self-interference cancellation path 2 cancels the signal S23 at frequency point f2, resulting in high isolation performance with two cancellation points.
5. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 4, characterized in that: The amplitude and phase of the self-interference cancellation path 1 and self-interference cancellation path 2 at frequency points f1 and f2 are reconfigurable. By controlling the amplitude and phase of the self-interference cancellation path 1 and self-interference cancellation path 2 at frequency points f1 and f2, signal S23 is canceled, achieving high isolation performance. The phase of the self-interference cancellation path 1 and self-interference cancellation path 2 is adjustable, and their operating center frequency is adjustable, so that the high isolation performance can switch between broadband isolation and narrowband isolation, achieving flexible reconfigurable isolation performance.
6. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 5, characterized in that: The self-interference cancellation path 1 cancels the signal S23 at frequency f1 in the following ways: The amplitude of the signal controlling the self-interference cancellation path 1 at frequency point f1 is the same as the amplitude of the S23 signal at frequency point f1, and the phase of the signal controlling the self-interference cancellation path 1 at frequency point f1 is 180 degrees different from the phase of the S23 signal at frequency point f1. Similarly, the self-interference cancellation path 2 cancels out signal S23 at frequency point f2 specifically as follows: The amplitude of the signal controlling the self-interference cancellation path 2 at frequency point f2 is the same as the amplitude of the S23 signal at frequency point f2, and the phase of the signal controlling the self-interference cancellation path 2 at frequency point f2 is 180 degrees different from the phase of the S23 signal at frequency point f2.
7. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 6, characterized in that: The self-interference cancellation path 1 includes two external varactor diodes CkBs, two parallel NRNs and one resistor. The two varactor diodes CkBs are connected across the two ends of the resistor. One end of the NRN is connected between the resistor and the varactor diodes CkBs, and the other end is grounded. The self-interference cancellation path 1 is connected to the LC resonators R3 and R6 through the two varactor diodes CkBs respectively. The amplitude of the self-interference cancellation signal is modulated by controlling the bias voltage applied to the two varactor diodes CkBs.
8. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 7, characterized in that: The NRN of the self-interference cancellation path 1 includes an inductor and a varactor diode CBs connected in parallel. One end of the inductor and the varactor diode CBs is grounded, and the other end of the inductor and the varactor diode CBs is connected to a varactor diode CkBs. By controlling the bias voltage applied to the two varactor diodes CBs, the phase of the self-interference cancellation signal is modulated, and the phase is controlled to be adjusted between 0 and 360 degrees to meet the phase requirement of signal S23 canceling at frequency point f1.
9. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 6, characterized in that, The self-interference cancellation path 2 includes two varactor diodes CkBss, two parallel NRNs, and one resistor. The two varactor diodes CkBss are connected across the two ends of the resistor. One end of the NRN is connected between the resistor and the varactor diodes CkBss, and the other end is grounded. The self-interference cancellation path 2 is connected to the LC resonators R2 and R5 through the two varactor diodes CkBss respectively. The amplitude of the self-interference cancellation signal is modulated by controlling the bias voltage applied to the two varactor diodes CkBss.
10. A reconfigurable microwave filter circulator with adjustable self-interference isolation as described in claim 9, characterized in that: The NRN of the self-interference cancellation path 2 includes an inductor and a varactor diode CBss connected in parallel. One end of the inductor and the varactor diode CBss is grounded, and the other end of the inductor and the varactor diode CBss is connected to a varactor diode CkBss. By controlling the bias voltage applied to the two varactor diodes CBss, the phase of the self-interference cancellation signal is modulated, and the phase is controlled to be adjusted between 0 and 360 degrees to meet the phase requirement of signal S23 canceling at frequency point f2.