A tunable solid-state waveguide filter in the terahertz band

Abstract

The application belongs to the technical field of radio frequency components, and discloses a tunable solid-state waveguide filter in a terahertz frequency band, which comprises a waveguide upper cavity, a waveguide lower cavity and a quartz substrate filter circuit; the waveguide upper cavity and the waveguide lower cavity are matched to form a waveguide transmission cavity; the quartz substrate filter circuit comprises a quartz substrate, a C-shaped resonator circuit arranged on the quartz substrate and a uniform impedance resonator circuit; the C-shaped resonator circuit comprises a C-shaped resonator, and the uniform impedance resonator circuit comprises a plurality of uniform impedance resonators; the C-shaped resonator and the plurality of uniform impedance resonators are alternately and spacedly arranged on the quartz substrate along a signal propagation direction; by changing the structural parameters of the quartz substrate filter circuit or replacing the quartz substrate filter circuit with different structural parameters, the center frequency and the passband bandwidth of the filter can be adjusted. The application has the advantages of low loss of the waveguide and tunability of the planar circuit, and is suitable for a terahertz transceiver system.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency component technology, and in particular relates to a terahertz band tunable solid-state waveguide filter. Background Technology

[0002] With the rapid increase in demand for wireless communication system services, the radio spectrum allocated to communication systems in the future will inevitably be pushed to higher frequency bands to accommodate the ever-increasing traffic. The terahertz band (0.1-10 THz) has become a research hotspot due to its abundant spectrum resources. Among them, the WR-4 band (170-260 GHz), as one of the terahertz windows, has important applications in high-speed communication and radar systems due to its ultra-wide bandwidth and high-speed transmission capabilities. Filters, as important frequency-selective devices, function to allow desired frequency signals to pass through while reflecting unwanted interference frequency signals. Commonly used microstrip and stripline filters have the advantages of small size and easy integration into microwave active circuits. Therefore, they are widely used in radio frequency (RF) and microwave circuits. However, the loss of these compact transmission lines, such as microstrip lines, increases with frequency. Rectangular waveguides have the advantages of low loss and high power capacity, and their size shrinks dramatically in the millimeter-wave frequency range or even higher frequencies. Therefore, waveguide filters have high application value in the high-frequency band.

[0003] Traditional waveguide filters suffer from drawbacks such as large size, heavy weight, and complex manufacturing processes. With the rapid development of wireless communication systems, it is necessary not only to address these shortcomings of waveguide devices but also to improve their performance. For waveguide devices, especially in highly integrated and complex systems, the requirements for smaller size and better electrical performance are increasingly stringent. This type of filter technology cannot be directly transferred to the terahertz band (short wavelength, low error tolerance), and most current terahertz band filters use solid-state waveguide structures, lacking the advantage of band tunability. Furthermore, the main resonances and couplings of traditional terahertz solid-state waveguide filters are typically handled by fixed structures such as three-dimensional metal cavities and coupling windows, with their center frequency, passband bandwidth, and transmission zero position strongly coupled to the solid-state geometry after fabrication. When the operating frequency band needs adjustment, or when manufacturing errors cause frequency shifts, it is usually necessary to re-fabricate the waveguide cavity, replace the entire filter, or introduce additional mechanical or active tuning mechanisms, making it difficult to achieve band reconfiguration while maintaining the main solid-state waveguide structure unchanged. Waveguide filters based on quartz substrate filtering circuits ingeniously combine the low-loss performance of waveguides with the compactness and tunability of planar circuits. They allow for dynamic bandgap adjustment without altering the solid-state structure, resulting in high performance, small size, and high reliability. This significantly improves the system's tolerance to manufacturing errors, playing an indispensable role in the miniaturization and integration of wireless communication devices. Furthermore, traditional solid-state waveguide filters are widely used in terahertz transmitter / receiver systems. If a filter's performance fails due to manufacturing or design deviations, replacing it is equivalent to disassembling and reassembling the entire core RF module, which is not only cumbersome and time-consuming but also results in significant cost and chip waste. In summary, existing technologies have many shortcomings. To address these shortcomings, this invention proposes a terahertz band tunable solid-state waveguide filter. Summary of the Invention

[0004] The purpose of this invention is to provide a terahertz-band tunable solid-state waveguide filter. By dynamically tuning the passband response of a solid-state link system, it achieves the core function of "dynamically adjusting the frequency band selection without changing the solid-state structure," precisely matching the dual requirements of structural stability and frequency band flexibility of the solid-state link system. The core technical concept of this invention lies in decoupling the functions of the "fixed waveguide mechanical carrier" and the "configurable frequency-selective core": the waveguide cavity mainly undertakes the functions of low-loss waveguiding, electromagnetic shielding, mechanical support, and waveguide interface, while the main resonance and coupling functions that determine the center frequency, passband bandwidth, and transmission zero point of the filter response are undertaken by a detachable quartz substrate filter circuit. Therefore, without reprocessing the waveguide cavity, the frequency band of the solid-state waveguide platform can be reconstructed by replacing or reconfiguring the quartz substrate filter circuit, balancing the requirements of solid-state implementation with tuning flexibility, and achieving a balance between stability and adaptability.

[0005] To achieve the above objectives, this invention provides a terahertz-band tunable solid-state waveguide filter, comprising an upper waveguide cavity, a lower waveguide cavity, and a quartz substrate filter circuit. The lower waveguide cavity has a groove at its top, and the upper and lower waveguide cavities are joined to form a waveguide transmission cavity. The quartz substrate filter circuit is disposed within the groove of the lower waveguide cavity, thereby forming a detachable hybrid filter structure. The quartz substrate filter circuit includes a quartz substrate and a C-type resonator circuit and a uniform impedance resonator circuit disposed on the quartz substrate. The C-type resonator circuit includes a C-type resonator, and the uniform impedance resonator circuit includes multiple uniform impedance resonators. The C-type resonator and the multiple uniform impedance resonators are alternately arranged on the quartz substrate along the signal propagation direction. A bandpass response is formed through electromagnetic coupling between the two types of resonators, and multiple transmission zeros are formed on the lower and upper sides of the passband, respectively, thereby improving the frequency selectivity and out-of-band rejection capability of the filter. While keeping the waveguide cavity structure and dimensions unchanged, the center frequency and passband bandwidth of the filter can be adjusted by changing the structural parameters of the quartz substrate filter circuit, or by replacing it with a quartz substrate filter circuit with one that has different structural parameters. This structure allows for frequency calibration or band configuration by replacing the quartz substrate filter circuit when there are manufacturing errors in the waveguide cavity or when the system needs to change its operating frequency band, without requiring the entire waveguide cavity to be remanufactured. Therefore, this invention does not rely on changing the solid-state waveguide cavity itself to obtain different operating frequency bands, but rather achieves frequency response adjustment by changing a planar frequency selection module independent of the waveguide body. This transforms the problem of frequency band adjustment in traditional solid-state waveguide filters, which relies on changes in three-dimensional mechanical structures, into a problem of frequency band adjustment achieved through changes in the configuration of the planar filter circuit.

[0006] Optionally, the C-type resonator circuit and the uniform impedance resonator circuit form a bandpass response through electromagnetic coupling, and form three transmission zeros in the upper stopband and two transmission zeros in the lower stopband of the passband.

[0007] Optionally, the uniform impedance resonator circuit includes a first uniform impedance resonator, a second uniform impedance resonator, and a third uniform impedance resonator arranged sequentially along the signal propagation direction; the first and third uniform impedance resonators are used to generate transmission zeros in the upper stopband, and the second uniform impedance resonator is used to generate transmission zeros in the high-frequency region of the upper stopband that is far from the passband.

[0008] Optionally, the C-type resonator is used to generate two transmission zeros in the lower stopband.

[0009] Optionally, the waveguide cavity adopts an E-plane split structure, with a groove in the lower waveguide cavity for positioning and accommodating the quartz substrate. The quartz substrate filter circuit is fabricated using planar thin-film technology. This structure facilitates CNC machining of the waveguide cavity and the installation and replacement of the quartz substrate filter circuit, and is suitable for the mass production of filter circuits in different operating frequency bands.

[0010] Optionally, the input and output ends of the filter are provided with waveguide flange interfaces.

[0011] Optionally, by configuring quartz substrate filter circuits with different structural parameters, bandpass responses with center frequencies of 215 GHz, 225 GHz, 235 GHz, and 245 GHz can be obtained.

[0012] The technical effects of this invention are as follows:

[0013] The frequency band tunable waveguide filter proposed in this invention solves the frequency band tuning problem through a "fixed carrier + replaceable core" approach. This fundamentally avoids the "processing error equals scrap" defect of traditional solid-state waveguide filters that are not tunable. It eliminates the need to disassemble the entire system; simply opening the cavity and replacing the corresponding dielectric substrate meets performance requirements. By batch-producing quartz circuits with multiple frequency band responses, when the system experiences frequency deviations or needs to adapt to different frequency bands, there is no need to modify the main structure of the link system. Only the quartz circuit corresponding to the frequency band needs to be replaced, enabling dynamic and precise frequency band adjustment of the entire system, significantly improving fault tolerance and maintenance efficiency. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0016] Figure 1 This is a tooling cavity diagram of the WR-4 band tunable waveguide filter in an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the WR-4 band tunable waveguide filter in an embodiment of the present invention;

[0018] Figure 3 This is a diagram of the waveguide cavity geometry of the WR-4 band tunable waveguide filter.

[0019] Figure 4 Top view of the WR-4 band tunable waveguide filter;

[0020] Figure 5 The diagram shows the structure of the C-type resonator and its corresponding S-parameter simulation diagram in an embodiment of the present invention; wherein, Figure 5 (a) is a structural diagram of a C-type resonator. Figure 5 (b) is a simulation diagram of the S-parameters of the C-type resonator;

[0021] Figure 6 The diagram shows the structure of the uniform impedance resonator in this embodiment of the invention and the corresponding S-parameter simulation diagram; wherein, Figure 6 (a) is a structural diagram of each uniform impedance resonator. Figure 6 (b) shows the S-parameter simulation diagrams for each uniform impedance resonator;

[0022] Figure 7 The diagram shows the structure of the 215GHz waveguide bandpass filter in this embodiment of the invention, along with the corresponding S-parameter simulation and measured figures; wherein, Figure 7 (a) is a structural diagram of a 215 GHz waveguide bandpass filter. Figure 7 (b) shows the simulated and measured S-parameters of the 215GHz waveguide bandpass filter;

[0023] Figure 8 This is a simulation diagram of the S-parameters showing the changes in the main structural parameters of the 215GHz waveguide bandpass filter in this embodiment of the invention; wherein, Figure 8 (a) is a simulation diagram of S-parameters with varying structural parameter h0. Figure 8 (b) is a simulation diagram of the S-parameters with varying structural parameter h1;

[0024] Figure 9 The figures shown are simulation and measured S-parameters of the 225GHz waveguide bandpass filter, 235GHz waveguide bandpass filter, and 245GHz waveguide bandpass filter in this embodiment of the invention. Figure 9 (a) shows the simulated and measured S-parameters of a 225 GHz waveguide bandpass filter. Figure 9 (b) shows the simulated and measured S-parameters of the 235GHz waveguide bandpass filter. Figure 9 (c) shows the simulated and measured S-parameters of the 245GHz waveguide bandpass filter.

[0025] Labeling Explanation: 1. Waveguide upper cavity; 2. Waveguide lower cavity; 2.1. Groove; 3. Quartz substrate filter circuit; 3.1. Quartz substrate; 3.2. C-type resonator circuit; 3.2.1. First C-type resonator; 3.2.2. Second C-type resonator; 3.3. Uniform impedance resonator circuit; 3.3.1. First uniform impedance resonator; 3.3.2. Second uniform impedance resonator; 3.3.3. Third uniform impedance resonator; 4. Waveguide flange interface. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Example 1

[0032] like Figure 1 - Figure 9As shown, this embodiment provides a terahertz-band tunable solid-state waveguide filter, including an upper waveguide cavity 1, a lower waveguide cavity 2, and a quartz substrate filter circuit 3; the upper waveguide cavity 1 and the lower waveguide cavity 2 are coupled to form a waveguide transmission cavity; a groove 2.1 is provided at the top of the lower waveguide cavity, and the quartz substrate filter circuit 3 is detachably installed in the groove 2.1; the quartz substrate filter circuit 3 includes a quartz substrate 3.1 and a C-type resonator circuit 3.2 and a uniform impedance resonator circuit 3.3 disposed on the quartz substrate; The C-type resonator circuit 3.2 includes a first C-type resonator 3.2.1 and a second C-type resonator 3.2.2, and the uniform impedance resonator circuit 3.3 includes multiple uniform impedance resonators 3.3.1, 3.3.2, and 3.3.3. The C-type resonators and multiple uniform impedance resonators are arranged alternately and at intervals along the signal propagation direction on the quartz substrate 3.1. By changing the structural parameters of the quartz substrate filter circuit 3 or replacing it with a quartz substrate filter circuit with different structural parameters, the center frequency and passband bandwidth of the filter can be adjusted.

[0033] To achieve the above objectives, this embodiment adopts the following technical solution:

[0034] The system comprises an upper waveguide cavity 1, a quartz substrate filter circuit 3, and a lower waveguide cavity 2. The quartz substrate filter circuit 3 includes a uniform impedance resonator circuit 3.3, a C-type resonator circuit 3.2, and a quartz substrate 3.1, wherein the C-type resonator R0 and the uniform impedance resonators (R1, R2, R3) are arranged alternately on the quartz substrate. The upper waveguide cavity 1 and the lower waveguide cavity 2 are respectively mounted above and below the quartz substrate filter circuit 3, together forming a cavity to house the quartz substrate filter circuit. The input and output terminals can employ standard waveguide flanges, non-standard waveguide interfaces, waveguide-microstrip transitions, or other integrated interfaces. Impedance matching circuits, bias circuits, and millimeter-wave or terahertz active chips can also be further integrated onto the planar substrate.

[0035] The quartz substrate filter circuit is fabricated using planar thin-film circuit manufacturing technology.

[0036] The substrate for the filter planar circuit is not limited to quartz; it can also be made of high-resistivity silicon, alumina, sapphire, glass, or other low-loss dielectric materials suitable for millimeter-wave and terahertz frequency bands.

[0037] Uniform Impedance Resonator Circuit 3.3 by λ g / 2(λ) gThe circuit consists of two uniform impedance resonators (R1, R3) and R2, where the waveguide wavelength is at the resonant frequency. The uniform impedance resonators (R1, R3) generate two resonances (TZ) in the upper stopband and have low-pass characteristics; the uniform impedance resonator R2 generates one resonance (TZ) at a greater distance in the upper stopband to achieve wide stopband performance and enhance the coupling between the impedance resonator circuit and the C-type resonator circuit.

[0038] The C-type resonator circuit 3.2 consists of a C-type resonator R0, which generates two resonances, TZ, in the lower stopband and has high-pass characteristics.

[0039] In feasible implementations, the C-type resonator and uniform impedance resonator in the planar filter circuit can be replaced with a U-type resonator, an open-loop resonator, a step impedance resonator, a folded resonator, or other planar structures capable of forming corresponding resonance and transmission zeros. The number, arrangement, and coupling spacing of the resonators can be adjusted according to the filter order, bandwidth, and stopband suppression requirements.

[0040] The waveguide filter uses a waveguide cavity and a quartz substrate filter planar circuit, which can keep the size of the waveguide cavity unchanged. Only the structural parameters in the quartz substrate filter planar circuit can be adjusted to control the center frequency and bandwidth of the passband. This avoids the problems of low tolerance for processing errors and long system debugging time caused by the non-tunability of traditional solid-state waveguide filters, and achieves frequency band tunability, reducing design complexity and increasing adjustability.

[0041] In practice, the operating frequency band of the filter can be adjusted not only by replacing the substrate filter circuit with one that has different structural parameters, but also by using a pluggable filter module, a movable substrate, or other detachable structure to replace or reposition the planar filter circuit.

[0042] The waveguide cavity structure in this embodiment is simple and easily implemented by CNC technology. It is processed using an E-plane split waveguide structure. The upper waveguide cavity 1 is the upper half of the standard waveguide WR-4, and the lower waveguide cavity 2 is formed by adding grooves on both sides of the center of the lower half of the standard waveguide WR-4 to accommodate the quartz substrate 3.1. All right angles of the cavities in the model are rounded to fit the drill bit size in the CNC process.

[0043] The waveguide cavity is feasible and not limited to the WR-4 standard rectangular waveguide. Other standard or non-standard rectangular waveguides, ridge waveguides, partial height waveguides, and other waveguide structures can also be used, and the cavity size can be adjusted according to the target operating frequency. The waveguide cavity can adopt an E-plane split, H-plane split, multi-layer stacking, or top and bottom cover plate structure. The cavity can be machined from metals such as aluminum and copper, or it can be formed from silicon or other materials and then have a conductive metal layer set on the surface; the processing methods can include CNC milling, deep reactive ion etching, electroforming, or additive manufacturing.

[0044] Figure 1 This is an engineering diagram of the cavity structure of the WR-4 band tunable waveguide filter based on the quartz substrate filter circuit 3. It shows that the waveguide is fabricated using an E-plane split waveguide structure, where the waveguide is cut along its E-plane (i.e., a plane parallel to the wide side and the propagation direction) to form two metal blocks, which are then aligned and merged to form a closed cavity. The cavity structure is milled from the aluminum block using traditional CNC technology. The minimum drill bit diameter during fabrication is 0.2 mm, and the overall filter size is W×L×H = 20 mm × 15 mm × 20 mm. A standard UG-387 flange is machined onto the waveguide opening. The quartz substrate filter circuit 3 is fabricated using planar thin-film circuit technology.

[0045] Figure 2 This is a schematic diagram of the WR-4 band tunable waveguide filter based on a quartz substrate filter circuit. As shown in the figure, the waveguide structure based on the quartz substrate filter circuit consists of an upper waveguide cavity 1, a quartz substrate filter circuit 3, and a lower waveguide cavity 2, wherein the thickness of the quartz substrate 3.1 is 100 μm. Figure 4 This is a top view of the WR-4 band tunable waveguide filter based on a quartz substrate filter circuit. As shown in the figure, the quartz substrate 3.1 is located within the waveguide's lower cavity recess 2.1. The quartz substrate filter circuit 3 consists of the quartz substrate 3.1, a C-type resonator circuit 3.2, and a uniform impedance resonator circuit 3.3. Figure 5 It can be seen that the C-type resonator circuit 3.2 consists of a C-type resonator R0, which generates two resonances (TZ) in the lower stopband and has high-pass characteristics; Figure 6 As can be seen, the uniform impedance resonator circuit 3.3 consists of λg / 2 (λg is the waveguide wavelength at the resonant frequency) uniform impedance resonators (R1, R3) and uniform impedance resonator R2. The uniform impedance resonators (R1, R3) generate two resonances (TZ) in the upper stopband and exhibit low-pass characteristics. The uniform impedance resonator R2 generates one resonance (TZ) at a relatively far point in the upper stopband to achieve wide stopband performance. Figure 7 It can be seen that coupling the two resonator circuits forms a passband response, and generates three and two transmission zeros in the upper and lower stopbands, respectively, achieving wide stopband and high frequency selectivity. Figure 8 and Figure 9 It is evident that by keeping the waveguide cavity size constant and adjusting only the main structural parameters in the quartz substrate filter planar circuit, the center frequency and bandwidth of the passband can be controlled, achieving waveguide bandpass filters with center frequencies of 225GHz, 235GHz, and 245GHz, respectively, thus reducing design complexity and increasing adjustability. The above multi-frequency results further demonstrate that, under the condition that the main structure, size, and interface of the waveguide cavity remain consistent, multiple bandpass responses with different center frequencies can be obtained simply by configuring different quartz substrate filter circuits. This verifies the feasibility of decoupling the frequency selection function from the solid-state waveguide carrier and reconstructing the frequency band on the same waveguide platform.

[0046] Compared with the prior art, this embodiment has the following beneficial effects:

[0047] (1) This embodiment adopts a hybrid filtering structure combining a waveguide cavity and a quartz substrate filter circuit, with the main resonance and coupling functions of the filter located in the quartz substrate filter circuit. While keeping the waveguide cavity structure and dimensions unchanged, the center frequency and passband bandwidth of the filter can be adjusted by changing the structural parameters of the quartz substrate filter circuit, or by replacing it with a quartz substrate filter circuit with different structural parameters, thereby improving the adaptability of the same waveguide cavity to different operating frequency bands. Essentially, this transfers the main degree of freedom determining the filter frequency response from the fixed three-dimensional waveguide structure to a planar filter module that can be independently fabricated and replaced, transforming the waveguide cavity from a resonant entity strongly bound to a single operating frequency band into a reusable universal electromagnetic carrier, thus achieving decoupling of the waveguide mechanical carrier and frequency selection function at the structural level.

[0048] (2) In this embodiment, the quartz substrate is placed in the groove of the lower waveguide cavity, so that the quartz substrate filter circuit can be separately assembled with the upper waveguide cavity 1 and the lower waveguide cavity 2. When the actual operating frequency of the filter is deviated due to the influence of processing error, the operating frequency band can be adjusted by replacing the corresponding quartz substrate filter circuit 3. There is no need to reprocess the entire waveguide cavity and its standard interface. Therefore, the influence of waveguide cavity processing error on the frequency response of the filter can be reduced, and the time and cost required for device debugging and rework can be reduced, thereby improving the fault tolerance, maintainability and frequency band adaptability of the terahertz system.

[0049] (3) The quartz substrate filter circuit of this embodiment includes a C-type resonator circuit 3.2 and a uniform impedance resonator circuit 3.3. The C-type resonator is used to form a transmission zero on the lower side of the passband, and the uniform impedance resonator is used to form a transmission zero on the upper side of the passband. Through the coupling between the two types of resonators, two transmission zeros can be formed in the lower stopband and three transmission zeros in the upper stopband while forming a bandpass transmission response, thereby improving the frequency selectivity, stopband rejection and stopband coverage of the filter.

[0050] (4) This embodiment adopts a planar resonant structure combining a uniform impedance resonator and a C-type resonator. By adjusting the length, spacing and relative position of each resonator to the waveguide cavity, the resonant frequency, the coupling strength between the resonators and the external coupling strength can be controlled respectively. This is beneficial for independently or jointly adjusting the center frequency, bandwidth, transmission zero position and out-of-band suppression characteristics of the filter, thereby reducing the design complexity of filters in different operating frequency bands.

[0051] (5) Compared with the filter structure composed of multiple three-dimensional waveguide resonant cavities, this embodiment integrates multiple resonant units on the planar metal layer of the quartz substrate, which can reduce the space occupied by the resonant structure and is conducive to the miniaturization of the filter. At the same time, the quartz substrate can also serve as a carrier platform and interconnection platform for the filter circuit, which facilitates the further integration of impedance matching networks, bias circuits or millimeter-wave monolithic integrated circuit chips, thereby improving the integration of the RF front-end system.

[0052] (6) The quartz substrate filter circuit 3 in this embodiment can be fabricated using planar thin film technology. Compared with high-precision machining of complete three-dimensional waveguide cavities of different frequency bands, quartz substrate filter circuits with different structural parameters can be batch-produced on the same waveguide cavity platform, which is beneficial to improving the consistency of filter circuits in different batches and reducing the processing and maintenance costs of multi-frequency band devices.

[0053] (7) The quartz substrate 3.1 in this embodiment can itself serve as a carrier and interconnection platform, so that the filter circuit can be designed together with the impedance matching network, bias circuit, etc. on the same substrate. Then the MMIC chip can be directly connected to the corresponding position of the substrate through gold wire bonding or flip-chip bonding to realize a highly compact multi-chip module (MCM).

[0054] (8) The waveguide cavity in this embodiment adopts an E-plane split structure, which is formed by the upper waveguide cavity 1 and the lower waveguide cavity 2. The lower waveguide cavity 2 is provided with a groove for accommodating the quartz substrate. The right-angle positions inside the cavity are rounded according to the size of the CNC milling tool, so that the waveguide cavity can be processed by conventional CNC milling process, thereby reducing the machining difficulty of the terahertz waveguide filter.

[0055] (9) The input and output terminals of this embodiment are equipped with standard UG-387 waveguide flange interface 4, which can be directly connected to the test equipment or waveguide link of the corresponding band, reducing the impact of additional waveguide conversion structure on test results and system transmission performance, facilitating independent testing of filters and assembly application in terahertz transceiver systems.

[0056] (10) In this embodiment, under the condition of using the same waveguide cavity, by configuring quartz substrate filter circuit 3 with different structural parameters, bandpass responses with center frequencies of approximately 215 GHz, 225 GHz, 235 GHz and 245 GHz can be obtained respectively; the reflection coefficient in the passband of each filter is less than −15 dB, and multiple transmission zeros are formed on both sides of the passband, with extremely steep transition bands and extremely high out-of-band suppression, verifying the effectiveness of the structure in achieving frequency band adjustment, passband matching and out-of-band suppression.

[0057] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A terahertz-band tunable solid-state waveguide filter, characterized in that, The system includes an upper waveguide cavity (1), a lower waveguide cavity (2), and a quartz substrate filter circuit (3). The upper waveguide cavity (1) and the lower waveguide cavity (2) are joined together to form a waveguide transmission cavity. A groove (2.1) is provided on the top of the lower waveguide cavity, and the quartz substrate filter circuit (3) is detachably installed in the groove (2). The quartz substrate filter circuit (3) includes a quartz substrate (3.1) and a C-type resonator circuit (3.2) and a uniform impedance resonator circuit (3.3) disposed on the quartz substrate (3.1). The C-type resonator circuit (3.2) includes a C-type resonator, and the uniform impedance resonator circuit (3.3) includes multiple uniform impedance resonators. The C-type resonator and the multiple uniform impedance resonators are arranged alternately along the signal propagation direction on the quartz substrate (3.1). By changing the structural parameters of the quartz substrate filter circuit (3) or replacing it with a quartz substrate filter circuit with different structural parameters, the center frequency and passband bandwidth of the filter can be adjusted.

2. The terahertz-band tunable solid-state waveguide filter according to claim 1, characterized in that, The C-type resonator circuit (3.2) and the uniform impedance resonator circuit (3.3) form a bandpass response through electromagnetic coupling, and form three transmission zeros in the upper stopband and two transmission zeros in the lower stopband of the passband, respectively.

3. A terahertz-band tunable solid-state waveguide filter according to claim 2, characterized in that, The uniform impedance resonator circuit (3.3) includes a first uniform impedance resonator (3.3.1), a second uniform impedance resonator (3.3.2), and a third uniform impedance resonator (3.3.3) arranged sequentially along the signal propagation direction; the first uniform impedance resonator (3.3.1) and the third uniform impedance resonator (3.3.3) are used to generate transmission zeros in the upper stopband, and the second uniform impedance resonator (3.3.2) is used to generate transmission zeros in the high-frequency region of the upper stopband that is far from the passband.

4. A terahertz-band tunable solid-state waveguide filter according to claim 2, characterized in that, The C-type resonator is used to generate two transmission zeros in the lower stopband.

5. A terahertz-band tunable solid-state waveguide filter according to claim 1, characterized in that, The quartz substrate filter circuit (3) is fabricated using a planar thin-film circuit fabrication process.

6. A terahertz-band tunable solid-state waveguide filter according to claim 1, characterized in that, The filter is equipped with waveguide flange interfaces (4) at both its input and output ends.

7. A terahertz-band tunable solid-state waveguide filter according to claim 1, characterized in that, By configuring quartz substrate filter circuits (3) with different structural parameters, bandpass responses with center frequencies of 215 GHz, 225 GHz, 235 GHz and 245 GHz can be obtained.

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