A terahertz filter

Abstract

This invention discloses a terahertz filter, relating to the field of filter technology, comprising: a flange with four symmetrically arranged metal resonant cavities along its cross-section, each adjacent metal resonant cavity having a coupling structure; two standard waveguide transition structures, each including a transition structure and a transmission structure, the transition structure including a transition block and a reverse step structure on one side thereon, and the transmission structure including a transmission block on the other side of the transition block; and two gaskets disposed on both sides of the flange, each gasket having a gap waveguide structure in its center, the gap waveguide structure including a bed of nails structure and an impedance transformation structure. This invention integrates traditional waveguide design methods into the flange, achieving excellent electrical performance with low loss and high selectivity in a compact size. The designed gap waveguide structure further improves the performance of this filter.

Description

Technical Field

[0001] This invention relates to the field of filter technology, and in particular to a terahertz filter. Background Technology

[0002] Filters are an important component of communication systems, their main function being to extract signals at frequencies of interest and suppress other unwanted signals. Because terahertz communication systems place high demands on the electrical performance, size, and integration capabilities of filters, developing high-performance terahertz filters aligns perfectly with modern communication development trends and can significantly improve the performance of terahertz communication systems.

[0003] Coupled resonator theory is a common method for filter design. A well-designed coupling path can generate transmission zeros, thereby improving the filter's bandwidth selectivity. Under strict size requirements, the design of resonator layouts and coupling structures is crucial, as it significantly impacts the filter's electrical performance. In addition to the filter's electrical performance, the interconnection between the filter and other devices must also be considered; therefore, a suitable transition structure is needed to facilitate device integration into the system.

[0004] Terahertz filters designed and manufactured using traditional processes face problems such as high loss, low selectivity, and low performance. Summary of the Invention

[0005] This invention provides a terahertz filter that solves the problems of high loss, low selectivity, and low performance faced by terahertz filters designed and manufactured using traditional processes.

[0006] This invention provides a terahertz filter, comprising:

[0007] The flange has four metal resonant cavities symmetrically arranged along its cross section. Two of the metal resonant cavities are located in the upper part, and the other two are located in the lower part. There is a coupling structure between adjacent metal resonant cavities.

[0008] Two standard waveguide transition structures are symmetrically arranged inside the flange along the cross section; the two standard waveguide transition structures are arranged on one side of the four metal resonators and coupled to the two adjacent metal resonators; each of the standard waveguide transition structures includes a transition structure and a transmission structure, the transition structure includes a transition block and a reverse step structure arranged on one side thereon, the transition block has a standard waveguide port, and the transmission structure includes a transmission block arranged on the other side of the transition block;

[0009] Two gaskets are disposed on both sides of the flange. Each gasket has a gap waveguide structure in the middle. The gap waveguide structure includes a bed of nails structure and an impedance transformation structure. The bed of nails structure includes multiple metal rectangular protrusion units. The multiple metal rectangular protrusion units are periodically arranged into a multi-layer square array around the impedance transformation structure. The impedance transformation structure has a standard waveguide port in the middle.

[0010] Preferably, the four metal resonant cavities are a first metal resonant cavity, a second metal resonant cavity, a third metal resonant cavity, and a fourth metal resonant cavity. The first and second metal resonant cavities are coplanar, the third and fourth metal resonant cavities are coplanar, the first and fourth metal resonant cavities are symmetrical, and the second and third metal resonant cavities are symmetrical.

[0011] Preferably, the first and second metal resonant cavities are magnetically coupled and connected through a horizontal first rectangular window; the third and fourth metal resonant cavities are magnetically coupled and connected through a horizontal second rectangular window; the first and fourth metal resonant cavities are electrically coupled and connected through a circular through-hole; and the second and third metal resonant cavities are magnetically coupled and connected through a rectangular hole, wherein the rectangular hole is located away from the center of the resonant cavity.

[0012] Preferably, the thickness of each of the four metal resonant cavities is 300 μm; the length and width of the first and fourth metal resonant cavities are both 866 μm; and the length and width of the second and third metal resonant cavities are both 899 μm. The thickness of the first and second rectangular windows is 100 μm, the width is 300 μm, and the length is 439 μm. The thickness of the circular through-hole is 100 μm, and the radius is 180 μm. The thickness of the rectangular hole is 100 μm, the width is 200 μm, and the length is 480 μm.

[0013] Preferably, the standard waveguide transition structure has a thickness of 500 μm, the transition block has a thickness of 100 μm, a length of 1092 μm, and a width of 546 μm; the reverse step structure includes three reverse steps, each with a thickness of 100 μm and a width of 1092 μm, and the lengths of each step from top to bottom are 275 μm, 250 μm, and 100 μm, respectively; the transmission block has a width of 1092 μm, a length of 2000 μm, and a thickness of 300 μm.

[0014] Preferably, the transition block has an input waveguide port, from which the signal is input. The discontinuity loss is minimized by the reverse step structure, and then the signal is output to the metal resonant cavity through the transmission block.

[0015] Preferably, the gasket comprises a cylindrical disk with the same cross-sectional shape as the flange and four irregularly shaped metals distributed circumferentially. The cylindrical disk has a thickness of 60 μm, and the irregularly shaped metals each have a thickness of 140 μm.

[0016] Preferably, the length and width of the metal rectangular protrusion unit are both 250μm, the thickness is 100μm, and the interval between adjacent rectangular protrusion units is 325μm; the length and width of the impedance transformation structure are both 1300μm, and the thickness is 160μm.

[0017] Preferably, the flange is of standard UG-387 / MM with a thickness of 900μm, and the standard waveguide port is of standard WR-4.

[0018] Preferably, the terahertz filter is obtained by processing using three-dimensional micro-metal additive manufacturing technology.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The flange of this invention features four symmetrically arranged metal resonant cavities and two standard waveguide transition structures along its cross-section. Each standard waveguide transition structure is coupled to two adjacent metal resonant cavities. Each standard waveguide transition structure includes a transition structure and a transmission structure. The transition structure includes a transition block and a reverse step structure on one side, with a standard waveguide opening on the transition block. This invention integrates traditional waveguide design methods into the flange, achieving a high-performance filter system in the terahertz band. It achieves excellent electrical performance with low loss and high selectivity in a compact size. Simultaneously, a gap waveguide structure is incorporated, including a bed of nails structure and an impedance transformation structure. This designed gap waveguide structure enables the filter of this invention to achieve non-contact flange connection and realizes leakage-free signal transmission between flanges, further improving the performance of this filter. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0022] Figure 1 This is a side view of the terahertz filter of the present invention;

[0023] Figure 2 This is a cross-sectional view of the terahertz filter of the present invention;

[0024] Figure 3This is a cross-sectional view of the standard waveguide adapter structure of the present invention;

[0025] Figure 4 This is a structural diagram of the metal resonant cavity of the present invention;

[0026] Figure 5 This is a schematic diagram showing the connection relationship of the metal resonant cavity of the present invention;

[0027] Figure 6 This is a diagram of the standard waveguide adapter structure of the present invention;

[0028] Figure 7 This is a side sectional view of the standard waveguide adapter structure of the present invention;

[0029] Figure 8 This is a top view of the gap waveguide structure of the present invention;

[0030] Figure 9 This is a three-dimensional diagram of the gap waveguide structure of the present invention;

[0031] Figure 10 This is a schematic diagram of the simulation results of the standard waveguide transition structure of the present invention;

[0032] Figure 11 This is a schematic diagram showing the final simulation results of the filter structure of the present invention.

[0033] In the diagram: 101-Terahertz filter, 102-Flange, 103-Standard waveguide adapter structure, 104-Gasket, 105-Gap waveguide structure, 106-Release hole, 201-First metal resonant cavity, 202-Second metal resonant cavity, 203-Third metal resonant cavity, 204-Fourth metal resonant cavity, 205-First rectangular window, 206-Rectangular hole, 207-Second rectangular window, 208-Circular through hole, 301-Transition block, 302-Reverse step structure, 303-Transmission block, 400-Cylindrical disk, 401-Irregular metal, 402-Bed of nails structure, 403-Impedance transformation structure, 404-Metal rectangular convex unit. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Reference Figure 1-9This invention provides a terahertz filter 101, comprising a flange 102, multiple metal resonant cavities, two standard waveguide transition structures 103, two gaskets 104, and a gap waveguide structure 105. The filter is manufactured using three-dimensional micro-metal additive manufacturing technology, with all metal materials being copper. The flange 102 conforms to the UG-387 / UM standard, with a thickness of 9 layers and 900μm. The manufacturing process involves layer-by-layer processing, with each layer being 100μm. The standard waveguide port conforms to the WR-4 standard, with a length of 1092μm and a width of 546μm to meet the filtering range requirements of the terahertz filter. Each metal resonant cavity has the same length and width, and a thickness of 3 layers and 300μm. Several identical release holes 106, each 100μm × 100μm × 100μm, are formed on the surface of the flange 102 to release photoresist. Multiple release holes 106 are opened inward on the upper and lower surfaces corresponding to the resonant cavity and the transition structure within the flange 102, and are periodically distributed at equal intervals. They are used to release the photoresist during the processing and have no specific positional requirements.

[0036] Flange 102 is a standard flange with four symmetrically arranged metal resonant cavities along its cross-section. Two are located at the top and two at the bottom, and each adjacent metal resonant cavity has a specific coupling structure. Specifically, all four metal resonant cavities function as resonators, with dimensions similar to their operating frequency. They include a first metal resonant cavity 201, a second metal resonant cavity 202, a third metal resonant cavity 203, and a fourth metal resonant cavity 204. The first and second metal resonant cavities 201 and 202 are coplanar, as are the third and fourth metal resonant cavities 203 and 204. The first and fourth metal resonant cavities 201 and 204 are symmetrical, as are the second and third metal resonant cavities 202 and 203.

[0037] The thickness of each of the four metal resonant cavities is 300 μm. The length and width of the first metal resonant cavity 201 and the fourth metal resonant cavity 204 are both 866 μm, and the length and width of the second metal resonant cavity 202 and the third metal resonant cavity 203 are both 899 μm.

[0038] To meet the requirements of cross-coupling, a total of four windows are opened to connect adjacent resonant cavities. Specifically, the first metal resonant cavity 201 and the second metal resonant cavity 202 are magnetically coupled and connected through a horizontal first rectangular window 205. The third metal resonant cavity 203 and the fourth metal resonant cavity 204 are magnetically coupled and connected through a horizontal second rectangular window 207. The first rectangular window 205 and the second rectangular window 207 are both 100 μm thick, 300 μm wide, and 439 μm long. The first metal resonant cavity 201 and the fourth metal resonant cavity 204 are electrically coupled and connected through a circular through-hole 208. The second metal resonant cavity 202 and the third metal resonant cavity 203 are magnetically coupled and connected through a rectangular hole 206, which is located away from the center of the resonant cavity. The circular through hole 208 has a thickness of 100μm and a radius of 180μm, while the rectangular hole 206 has a thickness of 100μm, a width of 200μm, and a length of 480μm.

[0039] Two standard waveguide transition structures 103 are used for the transition between the standard waveguide and four metallic resonant cavities. Each standard waveguide transition structure is 500 μm thick and includes a transition structure and a transmission structure. The transition structure includes a transition block 301 and a reverse step structure 302 disposed on one side thereon. The transmission structure includes a transmission block 303 disposed on the other side of the transition block 301. Specifically, the transition structure is located on the left side, and the transmission structure is located on the right side. The transition block 301 is 100 μm thick, and its length and width are the same as the WR-4 waveguide aperture, with a length of 1092 μm and a width of 546 μm. The reverse step structure 302 includes three reverse steps, each with a thickness of 100 μm and a width of 1092 μm. The lengths of each step from top to bottom are 275 μm, 250 μm, and 100 μm, respectively. The transmission block 303 is 1092 μm wide, 2000 μm long, and 300 μm thick.

[0040] An input waveguide port 304 is provided on the transition block 301. At the input and output ends, there is a standard waveguide transition structure, which is symmetrically distributed about the center cross section of the flange 102. The signal is input from the input waveguide port 304 above the transition part, and the discontinuity loss is minimized by the three-layer reverse step structure. Then, it is output to the metal resonant cavity through the transmission part. The output end transition structure has the opposite function and works in the same way.

[0041] Two gaskets are disposed on both sides of the flange 102. Each gasket is 200μm thick and includes a cylindrical disk 400 with the same cross-sectional shape as the flange 102 and four irregular metals 401 distributed circumferentially. The cylindrical disk 400 is 60μm thick and the irregular metals 401 are all 140μm thick.

[0042] Each spacer has a gap waveguide structure at its center. The gap waveguide structure includes a bed of nails structure 402 and an impedance transformation structure 403. The bed of nails structure 402 includes multiple rectangular metal protrusion units 404, which are periodically distributed around a cuboid with a standard waveguide opening. Each rectangular metal protrusion unit 404 has a length and width of 250 μm and a thickness of 100 μm, with a spacing of 325 μm between adjacent units. These multiple rectangular metal protrusion units 404 are periodically arranged in a five-layer array around the impedance transformation structure 403. The impedance transformation structure 403 has a length and width of 1300 μm and a thickness of 160 μm. A standard waveguide opening is located in the center of the impedance transformation structure 403.

[0043] The thickness of the gasket is greater than the thickness of the nail bed structure 402 and the impedance transformation structure 403, thus creating a gap of 40μm. When it is necessary to connect flanges, the gap waveguide structure can achieve contactless flange connection and play a good electromagnetic shielding role to achieve leakage-free transmission between flanges 102.

[0044] The transition performance parameters of the standard waveguide transition structure of this invention are attached. Figure 10 As shown, within the 215GHz to 225GHz range, the return loss of this transition section is below 17dB, reaching -18dB at around 220GHz. This transition structure has the advantage of a simple structure, achieving ideal performance with only three steps. Furthermore, the structure is greatly simplified to meet process requirements, thereby reducing manufacturing errors.

[0045] The performance parameters of the terahertz filter of this invention are as follows: Figure 11 As shown, the center frequency is 220GHz, the passband range is 213GHz to 225GHz, the transmission zeros are located at 209GHz and 234GHz, the out-of-band rejection is greater than 32dB, and there is a zero at 209GHz and 234GHz, which greatly improves the frequency selectivity of the filter.

[0046] The performance specifications of the standard waveguide transition structure of this invention are as follows: return loss is below 17dB within the range of 215GHz to 225GHz, reaching -18dB at approximately 220GHz. The filter's 3dB passband range is 213GHz-225GHz, with an out-of-band rejection greater than 32dB, and zeros at both 209GHz and 234GHz, improving the filter's frequency selectivity.

[0047] In summary, the cavity resonator terahertz filter of this invention utilizes the basic design method of cross-coupled filters and is fabricated using three-dimensional micro-metal additive manufacturing technology to obtain a low-loss, high-selectivity terahertz filter. By integrating traditional waveguide design methods into the flange, a high-performance filter system in the terahertz band is achieved, realizing system miniaturization and lightweight design. The designed standard waveguide adapter structure is simple, meets performance requirements, and is easy to implement. The designed gap waveguide structure enables the filter of this invention to achieve non-contact flange connection capability and realizes leakage-free signal transmission between flanges 102, further improving the performance and operational flexibility of this filter.

[0048] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0049] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A terahertz filter, characterized in that, include: The flange (102) has four metal resonant cavities symmetrically opened along its cross section. Two of the metal resonant cavities are located in the upper part, and the other two are located in the lower part. There is a coupling structure between adjacent metal resonant cavities. Two standard waveguide transition structures are symmetrically arranged inside the flange (102) along the cross section; Two standard waveguide transition structures are disposed on one side of four metal resonators and coupled to two adjacent metal resonators; each of the standard waveguide transition structures includes a transition structure and a transmission structure. The transition structure includes a transition block (301) and a reverse step structure (302) disposed on one side thereof. The transition block (301) is provided with a standard waveguide port. The transmission structure includes a transmission block (303) disposed on the other side of the transition block (301). Two gaskets are disposed on both sides of the flange (102). Each gasket has a gap waveguide structure in the middle. The gap waveguide structure includes a bed of nails structure (402) and an impedance transformation structure (403). The bed of nails structure (402) includes multiple metal rectangular protrusion units (404). The multiple metal rectangular protrusion units (404) are periodically arranged into a multi-layer square array around the impedance transformation structure (403). The impedance transformation structure (403) has a standard waveguide port in the middle.

2. A terahertz filter as described in claim 1, characterized in that, The four metal resonant cavities are a first metal resonant cavity (201), a second metal resonant cavity (202), a third metal resonant cavity (203), and a fourth metal resonant cavity (204). The first metal resonant cavity (201) and the second metal resonant cavity (202) are coplanar, the third metal resonant cavity (203) and the fourth metal resonant cavity (204) are coplanar, the first metal resonant cavity (201) and the fourth metal resonant cavity (204) are symmetrical, and the second metal resonant cavity (202) and the third metal resonant cavity (203) are symmetrical.

3. A terahertz filter as described in claim 2, characterized in that, The first metal resonant cavity (201) and the second metal resonant cavity (202) are magnetically coupled and connected through a horizontal first rectangular window (205); the third metal resonant cavity (203) and the fourth metal resonant cavity (204) are magnetically coupled and connected through a horizontal second rectangular window (207); the first metal resonant cavity (201) and the fourth metal resonant cavity (204) are electrically coupled and connected through a circular through hole (208); the second metal resonant cavity (202) and the third metal resonant cavity (203) are magnetically coupled and connected through a rectangular hole (206), the rectangular hole (206) being located away from the center of the resonant cavity.

4. A terahertz filter as described in claim 3, characterized in that, The thickness of each of the four metal resonant cavities is 300 μm. The length and width of the first metal resonant cavity (201) and the fourth metal resonant cavity (204) are both 866 μm, and the length and width of the second metal resonant cavity (202) and the third metal resonant cavity (203) are both 899 μm. The thickness of the first rectangular window (205) and the second rectangular window (207) are both 100 μm, the width is both 300 μm, and the length is both 439 μm. The thickness of the circular through hole (208) is 100 μm and the radius is 180 μm. The thickness of the rectangular hole (206) is 100 μm, the width is 200 μm, and the length is 480 μm.

5. A terahertz filter as described in claim 1, characterized in that, The standard waveguide transition structure has a thickness of 500 μm, the transition block (301) has a thickness of 100 μm, a length of 1092 μm, and a width of 546 μm; the reverse step structure (302) includes three reverse steps, each step having a thickness of 100 μm and a width of 1092 μm, and the lengths of each step from top to bottom are 275 μm, 250 μm, and 100 μm, respectively; the transmission block (303) has a width of 1092 μm, a length of 2000 μm, and a thickness of 300 μm.

6. A terahertz filter as described in claim 1, characterized in that, The transition block (301) has an input waveguide port (304). The signal is input from the input waveguide port (304), and the discontinuity loss is minimized through the reverse step structure (302). Then, it is output to the metal resonant cavity through the transmission block (303).

7. A terahertz filter as described in claim 1, characterized in that, The gasket includes a cylindrical disk (400) with the same cross-sectional shape as the flange (102) and four irregular metals (401) distributed circumferentially. The cylindrical disk (400) has a thickness of 60 μm, and the irregular metals (401) each have a thickness of 140 μm.

8. A terahertz filter as described in claim 7, characterized in that, The length and width of the metal rectangular protrusion unit (404) are both 250 μm and the thickness is 100 μm, and the interval between adjacent rectangular protrusion units is 325 μm; the length and width of the impedance transformation structure (403) are both 1300 μm and the thickness is 160 μm.

9. A terahertz filter as described in claim 1, characterized in that, The flange (102) is selected according to the UG-387 / MM standard, with a thickness of 900μm, and the standard waveguide port is selected according to the WR-4 standard.

10. A terahertz filter as described in claim 1, characterized in that, The terahertz filter was obtained by processing using three-dimensional micro-metal additive manufacturing technology.

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