A Tunable Cavity Filter Coupler, Antenna Device and Communication Equipment

Abstract

An embodiment of the present application provides a tunable cavity filter coupler, an antenna device, and a communication device, which relate to the field of mobile communication technologies. The tunable cavity filter coupler includes a dielectric substrate, which includes a base layer and a metal layer provided on at least one surface of the base layer. The metal layer is provided with a ring coupler and a bias circuit. Among them, the ring coupler includes four center-loaded stub resonators sequentially distributed in the circumferential direction, and a varactor diode is connected to each of the center-loaded stub resonators. The metal layer further includes feed ports corresponding to and connected to the center-loaded stub resonators one by one; the bias circuit is disposed around the outer periphery of the ring coupler, and the bias circuit is electrically connected to the varactor diode. The tunable cavity filter coupler, the antenna device, and the communication device provided by the present application achieve frequency selectivity and a tunable passband function, and meet the requirements of multi-band operation.

Description

Technical Field

[0001] This application relates to the field of mobile communication technologies, and in particular, to a tunable cavity filter coupler, an antenna device, and a communication device. Background Art

[0002] A filtering Rat-Race coupler is a directional coupler whose internal transmission path has an annular structure, enabling a specific phase difference and power distribution to occur during signal transmission. Specifically, a traditional filtering Rat-Race coupler usually cascades two band-pass filters with the Rat-Race coupler.

[0003] However, most traditional filtering Rat-Race couplers have the problem of a fixed response of the filter coupler. This design lacks reconfigurability and flexibility and is difficult to meet the requirements for various functions such as different frequency bands, bandwidths, phase shifts, or power distributions. Summary of the Invention

[0004] Embodiments of this application provide a tunable cavity filter coupler, an antenna device, and a communication device, achieving frequency selectivity and a tunable passband function, and meeting the requirements for multi-band operation.

[0005] In a first aspect, embodiments of this application provide a tunable cavity filter coupler, including:

[0006] A dielectric substrate, including a base layer and a metal layer provided on at least one surface of the base layer. The metal layer is provided with an annular coupler and a bias circuit. Among them, the annular coupler includes four center-loaded stub resonators sequentially distributed in the circumferential direction, and a varactor diode is connected to each of the center-loaded stub resonators. The metal layer further includes feed ports corresponding to and connected to the center-loaded stub resonators one by one;

[0007] The bias circuit surrounds the outer periphery of the annular coupler, and the bias circuit is electrically connected to the varactor diode.

[0008] In a possible implementation, the four center-loaded stub resonators include a first stub resonator and a second stub resonator oppositely arranged in a first direction, and a third stub resonator and a fourth stub resonator oppositely arranged in a second direction.

[0009] Among them, the feed port connected to the first stub resonator is a in-phase input port, and the feed port connected to the second stub resonator is an anti-phase input port.

[0010] The third stub resonator and the fourth stub resonator are configured to divide the signal input from the in-phase input port into in-phase sub-signals with equal amplitude, and divide the signal input from the anti-phase input port into anti-phase sub-signals with equal amplitude.

[0011] In a possible implementation, the feeding port includes a first output port and a second output port, the first output port and the second output port are respectively connected to a third stub resonator and a fourth stub resonator,

[0012] The first stub resonator and the second stub resonator are configured to divide the signal flowing from the first output port to the second output port into sub-signals with equal amplitude and opposite phases, and divide the signal flowing from the in-phase input port to the anti-phase input port into sub-signals with equal amplitude and opposite phases.

[0013] In a possible implementation, the four center-loaded stub resonators all include a main body section and a branch section. The main body sections of the first stub resonator, the third stub resonator, and the fourth stub resonator all extend linearly, and the branch sections are located inside the corresponding main body sections and are perpendicularly connected to the main body sections.

[0014] The branch section of the second stub resonator is located outside the corresponding main body section.

[0015] In a possible implementation, bending portions parallel to the diagonal of the square are respectively formed at both ends of each main body section.

[0016] In a possible implementation, the varactor diode includes a first varactor diode, and the first varactor diode is disposed at one end of the branch section away from the main body section. A current-limiting resistor and a DC-blocking capacitor are further provided between the first varactor diode and the bias circuit.

[0017] In a possible implementation, the varactor diode further includes a second varactor diode, and the second varactor diode is disposed at the free end of the bending portion of the main body section.

[0018] In a possible implementation, the varactor diode includes a third varactor diode, and the third varactor diode is disposed between two adjacent feeding ports along the circumferential direction.

[0019] In a possible implementation, the varactor diode further includes:

[0020] A tapped varactor diode, disposed at the feeding port;

[0021] A grounded varactor diode, disposed at the feeding port for grounding;

[0022] The tapped varactor diode and the grounded varactor diode are connected in series, and one of the tapped varactor diode and the grounded varactor diode is arranged in a first direction, and the other is arranged in a second direction.

[0023] In a second aspect, the present application also provides an antenna device, which includes the tunable cavity filter coupler in any of the above possible implementation manners.

[0024] In a third aspect, the present application also provides a communication device, which includes the antenna device in any of the above possible implementation manners.

[0025] The tunable cavity filter coupler, antenna device, and communication device provided by the present application introduce a varactor diode and a bias circuit, making the coupler highly flexible. It can be optimized for different application scenarios, and by adjusting the bias voltage, the response characteristics of the coupler can be changed in real time to enable it to adapt to different frequency band, bandwidth, phase shift, or power distribution requirements. Additionally, through precise design and optimization, the coupler can achieve high-performance indicators such as low loss, high isolation, and good phase balance. Thus, the design of the tunable cavity filter coupler of the present application solves the problem of the fixed response of the filter coupler in the traditional Rat-Race coupler, and realizes the high-performance, reconfigurable, and highly flexible design of the tunable cavity filter coupler. Description of the Drawings

[0026] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0027] Figure 1 It is a schematic structural diagram of the tunable cavity filter coupler provided by the present application;

[0028] Figure 2 It is a schematic diagram of the change state of the center frequency of the tunable cavity filter coupler provided by the present application in the low-frequency band;

[0029] Figure 3 It is a schematic diagram of the change of the center frequency of the tunable cavity filter coupler provided by the present application in the relatively high-frequency band.

[0030] Reference Signs:

[0031] 100 - dielectric substrate; 110 - base layer;

[0032] 200 - ring coupler; 210 - center-loaded stub resonator; 210a - main body section; 210b - branch section; 210c - bending part; 211 - first stub resonator; 212 - second stub resonator; 213 - third stub resonator; 214 - fourth stub resonator;

[0033] 300 - bias circuit;

[0034] 400 - Varactor diode; 410 - First varactor diode; 420 - Second varactor diode; 430 - Third varactor diode; 440 - Tapped varactor diode; 450 - Grounded varactor diode;

[0035] 500 - Feeding port; 510 - In - phase input port; 520 - Anti - phase input port; 530 - First output port; 540 - Second output port;

[0036] 600 - Current - limiting resistor;

[0037] 700 - DC - blocking capacitor;

[0038] 800 - External DC source;

[0039] 900 - Ground via hole.

[0040] Through the above - mentioned drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed Description of the Embodiments

[0041] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0042] The filtering Rat - Race coupler is a type of directional coupler with an internal transmission path in a circular structure, which causes a specific phase difference and power distribution during signal transmission. Conventional filtering Rat - Race couplers usually cascade two band - pass filters with the Rat - Race coupler. However, this usually results in a large circuit volume, a relatively high additional insertion loss, and matching problems.

[0043] Specifically, the conventional method of cascading two band - pass filters to the Rat - race coupler leads to a large circuit size, an increase in insertion loss, and matching problems. Although the filtering Rat - race coupler, as a multifunctional monolithic device, solves some problems, the previously designed FRCs based on planar boards, low - temperature co - fired ceramics (LTCC) technology, substrate - integrated waveguides (SIW), circular patch resonators, dielectric resonators, rectangular cavity resonators, etc. have problems such as fixed filter - coupler response, lack of reconfigurability, and flexibility.

[0044] On the other hand, traditional reconfigurable filter couplers can be implemented using reconfigurable filter transmission lines. However, most of them only achieve single-band tunability. There are also implementations using piezoelectric actuator-loaded substrate integrated waveguide cavities and varactor-loaded stepped impedance resonators. However, the reconfigurability described above is designed by replacing the quarter-wavelength transmission line of the coupler prototype with the proposed resonator. Although this design achieves a certain degree of reconfigurability, it has limitations in multiple performance aspects. For example, the comprehensive performance in terms of insertion loss, return loss, port isolation, phase imbalance, etc. is not ideal. When some designs implement the reconfigurable function, they may sacrifice other performance indicators, such as the circuit size may be relatively large.

[0045] It can be seen that most traditional filter Rat-Race couplers have the problem of fixed filter-coupler response. This design lacks reconfigurability and flexibility, and it is difficult to meet the requirements of modern microwave circuits and communication systems for various functions such as different frequency bands, bandwidths, phase shifts, or power distributions. It also cannot satisfy the growing demands of multi-band or multi-functional microwave systems.

[0046] In view of this, the present application provides a tunable cavity filter coupler, an antenna device, and a communication device. By introducing varactor diodes and bias circuits, the coupler has high flexibility, can be optimized for different application scenarios, and can also change the response characteristics of the coupler in real time by adjusting the bias voltage, enabling it to adapt to different frequency band, bandwidth, phase shift, or power distribution requirements. In addition, through precise design and optimization, the coupler can achieve high-performance indicators such as low loss, high isolation, and good phase balance. Thus, the design of the tunable cavity filter coupler in the present application solves the problem of fixed filter-coupler response existing in traditional Rat-Race couplers, and realizes the high-performance, reconfigurability, and high-flexibility design of the tunable cavity filter coupler.

[0047] The following combines Figures 1 to 3 to describe a tunable cavity filter coupler according to an embodiment of the first aspect of the present application. Optionally, x is the first direction and y is the second direction.

[0048] Combined with Figure 1 , the tunable cavity filter coupler of this embodiment includes a dielectric substrate 100. The dielectric substrate 100 serves as the basis of the entire coupler and is usually made of high-performance microwave materials. The dielectric substrate 100 includes a base layer 110 and a metal layer provided on at least one surface of the base layer 110 for constructing the circuit structure.

[0049] Optionally, the dielectric substrate 100 can be Rogers RO4003C high-frequency board, which has the advantages of low loss, stable dielectric constant, strong high-temperature stability, etc. In some examples, the dielectric constant of the dielectric substrate 100 can be 3.55 F / m, the loss tangent is 0.0027, and the thickness is 0.508 cm.

[0050] The metal layer is provided with a ring coupler 200 and a bias circuit 300. Among them, the ring coupler 200 includes four center-loaded stub resonators 210 sequentially distributed along the circumference to achieve signal coupling and phase shift.

[0051] A varactor diode 400 is connected to each center-loaded stub resonator 210. It can be understood that the varactor diode 400 is an electronic component with the characteristic that its capacitance changes with voltage. By adjusting the voltage across its two ends, its capacitance value can be changed, thereby changing the resonant frequency of the resonator. In this way, the response of the entire coupler can be made tunable.

[0052] The metal layer also includes feed ports 500 that correspond to and are connected to the center-loaded stub resonators 210 one by one. These ports are used for inputting and outputting signals. In addition, better performance can be achieved by adjusting the impedance matching of the feed end.

[0053] The bias circuit 300 is disposed around the outer periphery of the ring coupler 200 and is electrically connected to the varactor diode 400. It can be understood that the bias circuit 300 is used to provide the required voltage for the varactor diode 400, thereby controlling its capacitance value. Specifically, by adjusting the bias voltage, the response characteristics of the coupler can be dynamically changed.

[0054] It can be seen that by introducing the varactor diode 400 and the bias circuit 300, the coupler has high flexibility, can be optimized for different application scenarios, and the response characteristics of the coupler can be changed in real time by adjusting the bias voltage, enabling it to adapt to different frequency bands, bandwidths, phase shifts or power distribution requirements. In addition, through precise design and optimization, the coupler can achieve high-performance indicators such as low loss, high isolation and good phase balance.

[0055] In this way, the design of the tunable cavity filter coupler of the present application solves the problem of the fixed response of the filter coupler existing in the traditional Rat-Race coupler by introducing the varactor diode 400 and the bias circuit 300, and realizes the high-performance, reconfigurable and highly flexible design of the tunable cavity filter coupler.

[0056] Optionally, an external DC source 800 is also provided on the dielectric substrate 100, and the external DC source 800 is used to connect to the bias circuit 300.

[0057] In some embodiments, in combination with Figure 1, the four center-loaded stub resonators 210 include a first stub resonator 211 and a second stub resonator 212 arranged oppositely along a first direction, and a third stub resonator 213 and a fourth stub resonator 214 arranged oppositely along a second direction. Among them, the feeding port 500 connected to the first stub resonator 211 is a in-phase input port 510, and the feeding port 500 connected to the second stub resonator 212 is an anti-phase input port 520.

[0058] The third stub resonator 213 and the fourth stub resonator 214 are configured to divide the signal input from the in-phase input port 510 into sub-signals with equal amplitude and in-phase, and divide the signal input from the anti-phase input port 520 into sub-signals with equal amplitude and anti-phase.

[0059] Optionally, the first direction and the second direction form a preset angle. Preferably, the first direction is perpendicular to the second direction.

[0060] It can be understood that the first stub resonator 211 and the second stub resonator 212 are arranged oppositely along the first direction and are respectively connected to the in-phase input port 510 and the anti-phase input port 520. This arrangement helps to achieve phase control and distribution of signals.

[0061] The third stub resonator 213 and the fourth stub resonator 214 are arranged oppositely along the second direction and are configured to divide the signal input from the in-phase input port 510 into sub-signals with equal amplitude and in-phase, and divide the signal input from the anti-phase input port 520 into sub-signals with equal amplitude and anti-phase. This design enables the coupler to handle complex signal distribution and phase relationships.

[0062] When the signal is input from the in-phase input port 510, the third stub resonator 213 and the fourth stub resonator 214 divide the signal into sub-signals with equal amplitude and in-phase. Thus, the signals on the two output ports have the same amplitude and phase.

[0063] When the signal is input from the anti-phase input port 520, the third stub resonator 213 and the fourth stub resonator 214 divide the signal into sub-signals with equal amplitude and anti-phase. Thus, the signals on the two output ports have the same amplitude but opposite phases.

[0064] Specifically, the two input ports are the in-phase input port 510 and the anti-phase input port 520 respectively, and the two are located at two opposite positions along the first direction. These two ports can be regarded as the "input pair" of the coupler. Correspondingly, there are also two output ports along the second direction, and the two are corresponding to the input ports. When the signal enters from the input port, it passes through the coupler and finally outputs from the output port.

[0065] It can be seen that by ingeniously constructing the first stub resonator 211 and the second stub resonator 212 and their cooperative working relationship with the third and fourth stub resonators 214, the functions of bidirectional signal transmission and phase adjustment are realized, and the flexibility and reconfigurability of the tunable cavity filter coupler are improved.

[0066] In some embodiments, in combination with Figure 1 , the feeding port 500 includes a first output port 530 and a second output port 540, and the first output port 530 and the second output port 540 are respectively connected to the third stub resonator 213 and the fourth stub resonator 214.

[0067] The first stub resonator 211 or the second stub resonator 212 is configured to divide the signal flowing from the first output port 530 to the second output port 540 into sub-signals with equal amplitude and opposite phase, and divide the signal flowing from the in-phase input port 510 to the anti-phase input port 520 into sub-signals with equal amplitude and opposite phase.

[0068] Optionally, the signal flowing from the first output port 530 to the second output port 540 is an interference signal.

[0069] Thus, taking the first output port 530 and the second output port 540 as an example, when the interference signal at the first output port 530 flows to the second output port 540, the interference signal will be distributed to the first stub resonator 211 and the second stub resonator 212. It can be understood that due to the design and impedance matching of the resonator, the distribution of the interference signal in the first stub resonator 211 and the second stub resonator 212 is of equal amplitude.

[0070] The design of the first stub resonator 211 and the second stub resonator 212 enables a preset phase difference to be generated when the signal passes through them, and the phase difference generated by the signal in the two is 180 degrees (i.e., opposite phase). The signal after phase adjustment continues to flow to the second output port 540. However, since the two signals are of equal amplitude and opposite phase, when they are superimposed at the second output port 540, they will cancel each other out, resulting in the output signal being zero or close to zero.

[0071] Similarly, when the interference signal at the in-phase input port 510 flows to the anti-phase input port 520, or when the interference signal at the anti-phase input port 520 flows to the in-phase input port 510, mutual cancellation will also be achieved.

[0072] This design can reduce or eliminate the interference signal, and further achieve signal isolation between the first output port 530 and the second output port 540, and between the in-phase input port 510 and the anti-phase input port 520.

[0073] In this way, good port matching and port isolation can be achieved for the present application in various states. For example, during dual-band operation, the in-band isolation between the in-phase input port 510 and the anti-phase input port 520 is relatively good (such as greater than 28 dB, 33 dB, etc.), and the return loss between the first output port 530 and the second output port 540 is relatively good (such as greater than 14 dB, 18 dB, etc.). The good port characteristics help reduce signal reflection and crosstalk, and improve the performance of the communication system.

[0074] In some embodiments, in combination with Figure 1 , the four center-loaded stub resonators 210 all include a main body section 210a and a branch section 210b. It can be understood that each center-loaded stub resonator 210 is composed of the main body section 210a and the branch section 210b. This design helps achieve the preset electromagnetic performance and signal processing capabilities.

[0075] The main body sections 210a of the first stub resonator 211, the third stub resonator 213, and the fourth stub resonator 214 all extend linearly, and the branch sections 210b are located inside the corresponding main body sections 210a and are perpendicularly connected to the main body sections 210a. Among them, the linear design of the above three main body sections 210a helps maintain the continuity and stability of the signal and is also convenient for connection with other circuit elements. The layout design of the branch sections 210b helps achieve local regulation and phase fine-tuning of the signal, ensuring that the sub-signals maintain an accurate phase relationship during transmission and improving the performance and reliability of the overall system.

[0076] The branch section 210b of the second stub resonator 212 is located outside the corresponding main body section 210a. This design is used to achieve specific phase relationships or signal distribution requirements. For example, when the signal passes through the second stub resonator 212, the outer layout of its branch section 210b can effectively adjust the signal phase to ensure an anti-phase effect with the sub-signal generated by the first stub resonator 211.

[0077] Exemplarily, when the interference signal is transmitted to the second stub resonator 212 and the first stub resonator 211, the signal will be divided into two equal-amplitude and opposite components, thereby achieving mutual cancellation and effectively reducing the influence of the interference signal and improving the overall performance. Through the layout design of the center-loaded stub resonator 210, not only the efficient transmission of the signal and the precise control of the phase are achieved, but also the anti-interference ability is significantly improved.

[0078] In addition, the synergistic effect of each stub resonator further optimizes the signal transmission efficiency and ensures stable operation in a high-frequency environment.

[0079] In some embodiments, in combination with Figure 1 , a bent portion 210c parallel to the diagonal of the square is formed at each end of each main body section 210a.

[0080] This design increases the electrical length of the main section 210a, which helps to adjust the resonant frequency of the resonator. In addition, the bent portion 210c can also affect the phase response of the signal. By adjusting the position and shape of the bent portion 210c, the phase balance and phase stability of the coupler can be optimized.

[0081] Specifically, during actual operation, by adjusting the parameters of the bent portion 210c, precise control of performance indicators such as resonant frequency, bandwidth, and phase response can be achieved, improving the flexibility of the tunable cavity filter coupler.

[0082] In some embodiments, in combination with Figure 1 , the varactor diode 400 includes a first varactor diode 410. The first varactor diode 410 can be a stub-loaded varactor diode. Optionally, the model of the first varactor diode 410 can be SMV1413.

[0083] The first varactor diode 410 is disposed at one end of the branch section 210b away from the main section 210a. A current-limiting resistor 600 and a DC-blocking capacitor 700 are also provided between the first varactor diode 410 and the bias circuit 300. Optionally, the resistance value of the current-limiting resistor 600 can be 100 kΩ. Optionally, the capacitance value of the DC-blocking capacitor 700 can be 100 pF.

[0084] This design of the varactor diode changes the capacitance value by adjusting the bias voltage, thereby precisely controlling the resonant frequency and phase response. By adjusting the parameters of the current-limiting resistor 600 and the DC-blocking capacitor 700, the performance of the bias circuit 300 is further optimized.

[0085] Exemplarily, when adjusting the first varactor diode 410, it will mainly affect the upper passband, such as making the upper passband frequency range wider, thereby improving the overall frequency band utilization rate.

[0086] It can be understood that the main purpose of setting the current-limiting resistor 600 between the first varactor diode 410 and the bias circuit 300 is to protect the first varactor diode 410 from being impacted by excessive current. When the bias voltage changes, the current-limiting resistor 600 can limit the magnitude of the current passing through the first varactor diode 410, preventing it from being damaged due to overheating.

[0087] The function of the DC-blocking capacitor 700 is to isolate the AC signal (i.e., the RF signal) from the DC bias voltage. It allows the RF signal to pass through smoothly while preventing the DC bias voltage from interfering with the RF circuit. In this way, it can be ensured that the first varactor diode 410 can maintain its tuning function while not affecting the RF performance of the tunable cavity filter coupler.

[0088] Thus, by changing the bias voltage, the capacitance value of the first varactor diode 410 can be changed, thereby adjusting the resonant frequency of the coupler. This tuning function enables the tunable cavity filter coupler to adapt to different frequency bands and bandwidth requirements. In addition, the design of the current-limiting resistor 600 and the DC-blocking capacitor 700 protects the first varactor diode 410 from damage and ensures that the RF performance of the tunable cavity filter coupler is not interfered with by the DC bias voltage.

[0089] In some examples, the DC voltage first passes through the current-limiting resistor 600 and then grounds through an anti-connected varactor diode 400. At the same time, a DC-blocking capacitor 700 is also provided on one side of the varactor diode 400 to prevent DC signals from entering the bias circuit 300.

[0090] When the varactor diode 400 operates in the reverse breakdown region, it can be equivalent to an adjustable capacitor. When the bias voltage increases, the equivalent capacitance decreases. Based on this principle, the equivalent capacitance can be changed by changing the bias voltage, thereby changing the electrical structure of the entire circuit.

[0091] In some embodiments, in combination with Figure 1 , the varactor diode 400 further includes a second varactor diode 420, and the second varactor diode 420 can be a varactor diode with both ends loaded. Optionally, the model of the second varactor diode 420 can be SMV1237.

[0092] The second varactor diode 420 is provided at the free end of the bent portion 210c of the main body section 210a. This layout design enables the second varactor diode 420 to directly affect the electromagnetic performance of the main body section 210a, thereby further adjusting the resonant frequency and phase response of the coupler. By precisely adjusting the bias voltage of the second varactor diode 420, more precise control of the resonant frequency and phase can be achieved.

[0093] Exemplarily, when adjusting the second varactor diode 420, it has a greater impact on both the upper passband and the lower passband, thereby optimizing the overall band performance.

[0094] By introducing the second varactor diode 420, the tuning ability of the coupler is further enhanced. The resonant frequency and phase response of the tunable cavity filter coupler can be more precisely controlled by simultaneously adjusting the capacitance values of the first varactor diode 410 and the second varactor diode 420.

[0095] Optionally, similar to the first varactor diode 410, a current-limiting resistor 600 and a DC-blocking capacitor 700 are also provided between the second varactor diode 420 and the bias circuit 300. In this way, the second varactor diode 420 is protected from damage, and the RF performance of the tunable cavity filter coupler is ensured not to be interfered with by the DC bias voltage.

[0096] In some embodiments, in combination with Figure 1 , the varactor diode 400 includes a third varactor diode 430, which can be a center-loaded varactor diode. Optionally, the model of the third varactor diode 430 can be SMV1413.

[0097] The third varactor diode 430 is disposed between two circumferentially adjacent feed ports 500. This layout design enables the third varactor diode 430 to directly affect the electromagnetic coupling between the two feed ports 500, so as to further adjust the performance of the coupler. By introducing the third varactor diode 430, the coupling strength between the feed ports 500 can be controlled more precisely. In addition, it helps to optimize the bandwidth and frequency response of the tunable cavity filter coupler. By adjusting its capacitance value, fine adjustment of the operating frequency band of the tunable cavity filter coupler can be achieved.

[0098] Exemplarily, when adjusting the third varactor diode 430, it will mainly affect the lower passband, such as making the frequency range of the lower passband wider, thereby improving the overall frequency band utilization rate.

[0099] Optionally, similar to the first varactor diode 410 and the second varactor diode 420, a current-limiting resistor 600 and a DC-blocking capacitor 700 are also provided between the third varactor diode 430 and the bias circuit 300. In this way, the varactor diode 400 is protected from damage, and the RF performance of the tunable cavity filter coupler is also ensured not to be interfered by the DC bias voltage.

[0100] In some embodiments, in combination with Figure 1 , the varactor diode 400 further includes: a tapped varactor diode 440, disposed at the feed port 500; a grounded varactor diode 450, disposed at the feed port 500 for grounding.

[0101] Optionally, the model of the tapped varactor diode 440 can be SMV1255. Optionally, the model of the grounded varactor diode 450 can be SMV1247.

[0102] The tapped varactor diode 440 and the grounded varactor diode 450 are connected in series. One of the tapped varactor diode 440 and the grounded varactor diode 450 is disposed along a first direction, and the other is disposed along a second direction.

[0103] It can be understood that the tapped varactor diode 440 can change the electromagnetic characteristics at the feed port 500 by adjusting the capacitance value, affecting the overall performance of the coupler. The grounded varactor diode 450 is mainly used for grounding. By adjusting its capacitance value, the adjustment of the coupling to the ground can be achieved, and further affect the performance of the tunable cavity filter coupler.

[0104] Optionally, the tapped varactor diode 440 and the grounded varactor diode 450 can be vertically arranged. This design improves the utilization rate of the installation space, enhances the compactness, and can also reduce the electromagnetic interference between the two, ensuring the stable performance of the tunable cavity filter coupler.

[0105] It can be seen that due to the synergistic effect of the tapped varactor diode 440 and the grounded varactor diode 450, the two can jointly act on the feeding port 500 to achieve independent adjustment of the external coupling of the upper passband or the lower passband.

[0106] As described above, by reasonably designing the first varactor diode 410, the second varactor diode 420, the third varactor diode 430, the tapped varactor diode 440, and the grounded varactor diode 450, independent adjustment of the upper passband and the lower passband is achieved.

[0107] In some examples, combined with Figure 2 and Figure 3 , Figure 2 is a schematic diagram of the change state of the center frequency in the low-frequency band of this application, Figure 3 is a schematic diagram of the change of the center frequency in the relatively high-frequency band of this application. Among them, S11 is the return loss of the filter coupler, and S21 and S31 are the insertion losses.

[0108] It can be seen that in this application, the center frequency of the low-frequency band can vary within the range of 0.3 - 0.5 GHz, and the center frequency of the relatively high-frequency band can vary within the range of 0.82 - 1.04 GHz. Moreover, during the tuning process, the two frequency bands can be independently tuned. For example, referring to Figure 2 , the lower passband can be tuned within the range of 0.3 - 0.5 GHz, and the upper passband can be tuned within the range of 0.82 - 1.04 GHz.

[0109] Optionally, a grounding hole 900 is also provided on the dielectric substrate 100 to achieve grounding and improve the safety factor.

[0110] In addition, the second aspect embodiment of this application also provides an antenna device, including the tunable cavity filter coupler in any of the above embodiments.

[0111] The third aspect embodiment of this application also provides a communication device, including the antenna device in the above embodiment.

[0112] The antenna device and communication equipment provided by the present application introduce a varactor diode 400 and a bias circuit 300 by setting the above-mentioned tunable cavity filter coupler, enabling the coupler to have high flexibility, being able to be optimized for different application scenarios, and also being able to change the response characteristics of the coupler in real time by adjusting the bias voltage, so that it can adapt to different frequency band, bandwidth, phase shift or power distribution requirements. In addition, through precise design and optimization, the coupler can achieve high-performance indicators such as low loss, high isolation and good phase balance. Thus, by introducing the varactor diode 400 and the bias circuit 300, the problem of the fixed response of the filter coupler existing in the traditional Rat-Race coupler is solved, and the high-performance, reconfigurability and high-flexibility design of the antenna device and communication equipment are realized.

[0113] The present application can obtain good port matching and port isolation in multiple states. For example, in dual-band operation, the in-band isolation between the in-phase input terminal and the anti-phase input port 520 is good (such as greater than 28 dB, 33 dB, etc.), and the return loss between the first output port 530 and the second output port 540 is good (such as greater than 14 dB, 18 dB, etc.). Compared with the prior art, the good port characteristics help to reduce signal reflection and crosstalk and improve the performance of the communication system.

[0114] In addition, multiple transmission zeros are distributed between and outside the two passbands, bringing high frequency selectivity. Compared with some filter couplers with poor frequency selectivity in the prior art, this high frequency selectivity helps to better filter out unwanted frequency components and improve the purity of the signal and the communication quality.

[0115] It can be seen that the present application realizes a good reconfigurable filter power distribution response, has the advantages of a flexible and adjustable center frequency, good phase and amplitude characteristics, high in-band isolation, and can be extended to other-order multi-mode or multi-frequency situations, etc., and is expected to be widely used in the field of mobile communication.

[0116] It should be noted that the board type of the dielectric substrate 100, the type of each varactor diode 400, etc. mentioned above are all implementable examples, and can also be replaced with other types. However, it should be noted that in actual operation, after replacing the board type or the type of each varactor diode 400, the structural parameters of each device need to be readjusted to meet the required tuning range and application requirements.

[0117] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include the common general knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the precise structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A tunable cavity filter coupler, characterized in that, Comprising: A dielectric substrate (100) includes a base layer (110) and a metal layer provided on at least one surface of the base layer (110). The metal layer is provided with a ring coupler (200) and a bias circuit (300). Among them, the ring coupler (200) includes four center-loaded stub resonators (210) sequentially distributed in the circumferential direction. A varactor diode (400) is connected to each of the center-loaded stub resonators (210). The metal layer further includes feed ports (500) corresponding to and connected to the center-loaded stub resonators (210) one by one. The bias circuit (300) is disposed around the outer periphery of the ring coupler (200), and the bias circuit (300) is electrically connected to the varactor diode (400).

2. The tunable cavity filter coupler according to claim 1, wherein, The four center-loaded stub resonators (210) include a first stub resonator (211) and a second stub resonator (212) arranged opposite to each other in a first direction, and a third stub resonator (213) and a fourth stub resonator (214) arranged opposite to each other in a second direction. The first direction is perpendicular to the second direction. Among them, the feed port (500) connected to the first stub resonator (211) is a in-phase input port (510), and the feed port (500) connected to the second stub resonator (212) is an anti-phase input port (520). The third stub resonator (213) and the fourth stub resonator (214) are configured to divide the signal input from the in-phase input port (510) into in-phase sub-signals with equal amplitude, and divide the signal input from the anti-phase input port (520) into anti-phase sub-signals with equal amplitude.

3. The tunable cavity filter coupler according to claim 2, wherein The feed port (500) includes a first output port (530) and a second output port (540). The first output port (530) and the second output port (540) are respectively connected to the third stub resonator (213) and the fourth stub resonator (214). The first stub resonator (211) and the second stub resonator (212) are configured to divide the signal flowing from the first output port (530) to the second output port (540) into anti-phase sub-signals with equal amplitude, and divide the signal flowing from the in-phase input port (510) to the anti-phase input port (520) into anti-phase sub-signals with equal amplitude.

4. The tunable cavity filter coupler according to claim 2, wherein Each of the four center-loaded stub resonators (210) includes a main body section (210a) and a branch section (210b). The main body sections (210a) of the first stub resonator (211), the third stub resonator (213), and the fourth stub resonator (214) all extend linearly, and the branch sections (210b) are located inside the corresponding main body sections (210a) and are perpendicularly connected to the main body sections (210a). The branch section (210b) of the second stub resonator (212) is located outside the corresponding main section (210a), and the main section (210a) of the second stub resonator (212) has a perpendicular connection part and a parallel part with the corresponding branch section (210b).

5. The tunable cavity filter coupler according to claim 4, wherein Bending portions (210c) parallel to the diagonal of the square are respectively formed at both ends of the main section (210a) of the first stub resonator (211), the third stub resonator (213), and the fourth stub resonator (214). A bending portion (210c) parallel to the diagonal of the square is formed at one end of the main section (210a) of the second stub resonator (212), and a bending portion (210c) parallel to the diagonal of the square is formed at one end of the branch section (210b) of the second stub resonator (212).

6. The tunable cavity filter coupler according to claim 5, characterized in that, The varactor diode (400) includes a first varactor diode (410). The first varactor diode (410) is provided at one end of the branch section (210b) away from the main section (210a), and a current limiting resistor (600) and a DC blocking capacitor (700) are further provided between the first varactor diode (410) and the bias circuit (300).

7. The tunable cavity filter coupler according to claim 6, wherein The varactor diode (400) further includes a second varactor diode (420). The second varactor diode (420) is provided at the free end of the bending portion of the main section (210a).

8. The tunable cavity filter coupler according to claim 6, wherein The varactor diode (400) includes a third varactor diode (430). The third varactor diode (430) is provided between two adjacent feeding ports (500) in the circumferential direction, thereby directly affecting the electromagnetic coupling between the two feeding ports (500).

9. The tunable cavity filter coupler according to claim 8, wherein The varactor diode (400) further includes: A tapped varactor diode (440) provided at the feeding port (500); A grounded varactor diode (450) provided at the feeding port (500) for grounding; The tapped varactor diode (440) and the grounded varactor diode (450) are connected in series. One of the tapped varactor diode (440) and the grounded varactor diode (450) is arranged in a first direction, and the other is arranged in a second direction; The tapped varactor diode (440) changes the electromagnetic characteristics at the feeding port (500) by adjusting the capacitance value, and the grounded varactor diode (450) adjusts the coupling to the ground by adjusting the capacitance value.

10. An antenna device, characterized in that, Comprising: The tunable cavity filter coupler according to any one of claims 1-9.

11. A communication device, characterized in that, An antenna device comprising the tunable cavity filter coupler according to claim 10.

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