A micro-coaxial millimeter wave filter with source load coupling

Abstract

The present application belongs to the technical field of filter, and relates to a micro-coaxial millimeter wave filter with source-load coupling, comprising a metal shell; a first transmission line resonator, a second transmission line resonator, a third transmission line resonator, a fourth transmission line resonator, a fifth transmission line resonator and a sixth transmission line resonator are arranged in the metal shell, there is magnetic coupling between adjacent transmission line resonators, and there is electric coupling between the second transmission line resonator and the fifth transmission line resonator; an input feed structure is arranged on one side of the first transmission line resonator, and an output feed structure is arranged on one side of the sixth transmission line resonator; a source-load coupling structure is arranged between the input feed structure and the output feed structure; a first adapter structure is connected with the input feed structure, and a second adapter structure is connected with the output feed structure. The present application simultaneously realizes small size and good frequency band selectivity, and can adapt to the harsh requirements of high-performance millimeter wave systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of filters, and in particular relates to a micro-coaxial millimeter wave filter with source-load coupling. Background Art

[0002] With the continuous advancement of millimeter-wave technology, millimeter-wave systems are gradually developing toward high performance, small size, and high integration. As a crucial component of millimeter-wave systems, filters primarily extract signals at frequencies of interest and suppress other unwanted signals. To meet the stringent electrical performance and structural size requirements of millimeter-wave systems, filters must be miniaturized, exhibit high-band selectivity, and be easily interconnected. Filters with good band selectivity can provide higher signal quality for millimeter-wave systems, making these parameters particularly important in filter design. In millimeter-wave systems, filters designed with quarter-wave transmission line resonators are a leading technical solution, valued for their small size, mature design methods, and ease of fabrication.

[0003] Existing filters designed with quarter-wavelength transmission line resonators use different structures to establish electrical or magnetic coupling, and use coupling topologies containing cross-coupling to generate transmission zeros to improve the filter's band selectivity. However, under the narrow bandwidth application requirements of higher frequency bands and strict size constraints, excessive use of cross-coupling means complex coupling topologies and bloated filter structures, which greatly complicates the physical implementation of the filter. This limits further improvements in the filter's band selectivity and significantly restricts its application. Summary of the Invention

[0004] In view of this, the present invention provides a micro-coaxial millimeter-wave filter with source-load coupling, which can further improve the frequency band selectivity of the filter without excessive use of cross-coupling. It has the advantages of simple structure, small size, and good frequency band selectivity, which is conducive to the miniaturization and improvement of system integration, improves the reliability of the filter and broadens the application range of the filter.

[0005] The technical solution of the present invention is:

[0006] A micro-coaxial millimeter-wave filter with source-load coupling, comprising:

[0007] Metal housing;

[0008] a first transmission line resonator, a second transmission line resonator, a third transmission line resonator, a fourth transmission line resonator, a fifth transmission line resonator, and a sixth transmission line resonator, which are located within the metal housing and are all quarter-wavelength transmission line resonators; the first transmission line resonator and the sixth transmission line resonator, the second transmission line resonator and the fifth transmission line resonator, and the third transmission line resonator and the fourth transmission line resonator are all symmetrically arranged relative to the center of the metal housing; the first transmission line resonator and the second transmission line resonator, the second transmission line resonator and the third transmission line resonator, the third transmission line resonator and the fourth transmission line resonator, the fourth transmission line resonator and the fifth transmission line resonator, and the fifth transmission line resonator and the sixth transmission line resonator are magnetically coupled, and the second transmission line resonator and the fifth transmission line resonator are electrically coupled;

[0009] an input feed structure for generating an excitation signal on the first transmission line resonator;

[0010] an output feeding structure for coupling a signal on the sixth transmission line resonator;

[0011] A source-load coupling structure, comprising a first metal wall and a fourth slit, wherein the first metal wall is disposed between the input feed structure and the output feed structure, the upper surface and the lower surface of the first metal wall are respectively fixedly connected to the metal housing, and the fourth slit is provided on the first metal wall;

[0012] The first adapter structure and the second adapter structure are respectively used to connect to external equipment. The first adapter structure is connected to the input feed structure, and the second adapter structure is connected to the output feed structure.

[0013] Preferably, the first transmission line resonator includes a first metal inner core connected to the metal shell at one end open and the other end short-circuited, the second transmission line resonator includes a second metal inner core connected to the metal shell at one end open and the other end short-circuited, the second metal inner core is arranged on one side of the first metal inner core and is parallel to the first metal inner core, the third transmission line resonator includes a third metal inner core connected to the metal shell at one end open and the other end short-circuited, the third metal inner core is arranged on a side of the second metal inner core away from the first metal inner core and is parallel to the second metal inner core, and the third metal core One end of the resonator is connected to the column to achieve a short circuit, and the upper surface and the lower surface of the column are respectively fixedly connected to the inner surface of the metal shell. The sixth transmission line resonator includes a sixth metal inner core that is open-circuited at one end and short-circuited at the other end of the metal shell. The fifth transmission line resonator includes a fifth metal inner core that is open-circuited at one end and short-circuited at the other end of the metal shell. The fourth transmission line resonator includes a fourth metal inner core that is open-circuited at one end and short-circuited at the other end of the metal shell. The fourth metal inner core is arranged opposite to the third metal inner core, and one end of the fourth metal inner core is fixedly connected to the middle of the column to achieve a short circuit.

[0014] Preferably, the two ends of the first metal wall are fixedly connected to the inner wall and the column of the metal shell respectively, and a third gap is opened in the middle section of the first metal wall, and the third gap is located on the side of the open end of the second metal core. The metal shell is also provided with a second metal wall and a third metal wall arranged in parallel. The first metal wall passes through the middle of the second metal wall and the third metal wall and is perpendicular to the third metal wall and the second metal wall, and a pair of side surfaces of the first metal wall, the second metal wall and the third metal wall are respectively fixedly connected to a pair of inner surfaces of the metal shell, the second metal wall is located between the first metal core and the second metal core, and the third metal wall is located between the second metal core and the third metal core.

[0015] Preferably, the input feed structure includes:

[0016] a seventh metal inner core, disposed on a side of the first metal inner core away from the second metal inner core, the seventh metal inner core being in contact with an inner wall of the metal shell to form a grounding structure;

[0017] An eighth gap, used for generating excitation, is provided between the seventh metal inner core and the first metal inner core.

[0018] Preferably, the output feeding structure includes:

[0019] an eighth metal inner core, disposed on a side of the sixth metal inner core away from the fifth metal inner core, the eighth metal inner core being in contact with an inner wall of the metal shell to form a grounding structure;

[0020] A ninth gap, for generating excitation, is provided between the eighth metal inner core and the sixth metal inner core.

[0021] Preferably, the first switching structure includes:

[0022] A first epitaxial cavity is provided on a side surface of the metal shell, wherein the height of the first epitaxial cavity is lower than the height of the metal shell, and a first groove is formed on the upper surface of the first epitaxial cavity;

[0023] a ninth metal inner core, disposed in the first groove and connected to the seventh metal inner core, wherein the upper surface of the ninth metal inner core is flush with the top surface of the first epitaxial cavity;

[0024] a first metal support block, disposed below an end of the ninth metal inner core away from the metal shell, wherein an upper surface of the first metal support block is fixedly connected to the ninth metal inner core;

[0025] The first step block is arranged below the first metal support block, and the first step block is fixedly connected to the first epitaxial cavity.

[0026] Preferably, the second switching structure includes:

[0027] a second epitaxial cavity, disposed on another opposite side of the metal shell, wherein the height of the second epitaxial cavity is lower than the height of the metal shell and is flush with the first epitaxial cavity, and a second groove is formed on the upper surface of the second epitaxial cavity;

[0028] a tenth metal inner core, disposed in the second groove and connected to the eighth metal inner core, wherein the upper surface of the tenth metal inner core is flush with the top surface of the second epitaxial cavity;

[0029] a second metal support block, disposed below an end of the tenth metal inner core away from the metal shell, wherein an upper surface of the second metal support block is fixedly connected to the tenth metal inner core;

[0030] The second step block is arranged below the second metal support block, and the second step block is fixedly connected to the second epitaxial cavity.

[0031] Preferably, dielectric support strips are respectively provided on the first metal inner core, the second metal inner core, the third metal inner core, the fourth metal inner core, the fifth metal inner core, the sixth metal inner core, the seventh metal inner core, the eighth metal inner core, the ninth metal inner core and the tenth metal inner core.

[0032] Preferably, a plurality of release holes are provided on the surface of the metal shell, and the release holes are used to release the photoresist.

[0033] Compared with the prior art, the present invention provides a micro-coaxial millimeter-wave filter with source-load coupling, which uses multiple transmission line resonators to form a ring coupling path, and uses an input feeding structure to generate an excitation signal on the first transmission line resonator in the ring coupling path. After the signal is transmitted, the output feeding structure is used to export the signal on the last, i.e., the sixth, transmission line resonator in the ring coupling path, and the first switching structure and the second switching structure are used to achieve switching interconnection. In addition, the introduction of the source-load coupling structure in the structure can introduce more transmission zeros, further improving the frequency band selectivity of the filter. It has the advantages of simple structure, small size, and good frequency band selectivity, which is conducive to system miniaturization and improvement of integration, and improves the reliability of the filter. It can also meet the narrow bandwidth application requirements of higher frequency bands and strict size restrictions. It can well adapt to the high integration requirements of millimeter wave systems, has strong practicality, and is worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a top view of the present invention.

[0035] Figure 2 It is a top view of the present invention.

[0036] Figure 3 It is a MM cross-sectional view of the present invention.

[0037] Figure 4 It is a left view of the present invention.

[0038] Figure 5 It is a BB cross-sectional view of the present invention.

[0039] Figure 6 This is a coupling relationship diagram of the present invention.

[0040] Figure 7 This is a diagram of the S-parameter simulation results of the filter provided by the present invention. DETAILED DESCRIPTION

[0041] Currently used filters designed with quarter-wavelength transmission line resonators use different structures to establish electrical or magnetic coupling, and use a coupling topology containing cross-coupling to generate transmission zeros to improve the filter's band selectivity. However, under the narrow bandwidth application requirements of higher frequency bands and strict size constraints, excessive use of cross-coupling means that the coupling topology is complicated and the actual filter structure is bloated, which poses great difficulties for the physical implementation of the filter. This greatly limits the application of filters in these narrow bandwidth application requirements of higher frequency bands and strict size constraints.

[0042] In response to the above-mentioned technical problems, the present invention provides a micro-coaxial millimeter-wave filter with source-load coupling.

[0043] In order to enable those skilled in the art to better understand the technical solution of the present invention and to implement it, the following Figure 1 To the attached Figure 6 , clearly and comprehensively describe the technical solutions in the present invention.

[0044] It should be further explained that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0045] In addition, it should be understood that in the description of the embodiments of the present invention, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is merely a way to describe the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" refers to two or more than two.

[0046] The terms "first," "second," "third," and "fourth" below are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Thus, features qualified as "first," "second," "third," and "fourth" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0047] Example 1

[0048] like Figures 1 to 5 As shown, the present invention provides a micro-coaxial millimeter-wave filter with source-load coupling, including a metal shell 101. The metal shell 101 is made of H62 or H68. Six quarter-wavelength transmission line resonators are arranged inside the metal shell 101, namely a first transmission line resonator, a second transmission line resonator, a third transmission line resonator, a fourth transmission line resonator, a fifth transmission line resonator and a sixth transmission line resonator. The first transmission line resonator, the second transmission line resonator, the third transmission line resonator, the fourth transmission line resonator, the fifth transmission line resonator and the sixth transmission line resonator form a ring coupling path, and the coupling mode is as follows: the coupling between the first transmission line resonator and the second transmission line resonator, the coupling between the second transmission line resonator and the third transmission line resonator, the coupling between the third transmission line resonator and the fourth transmission line resonator, the coupling between the fourth transmission line resonator and the fifth transmission line resonator, and the coupling between the fifth transmission line resonator and the sixth transmission line resonator are all main couplings, and the main coupling is in the form of magnetic coupling; the coupling between the second transmission line resonator and the fifth transmission line resonator is cross coupling, and the cross coupling is in the form of electrical coupling. In addition to the coupling mentioned above, there is no other coupling between the multiple transmission line resonators.

[0049] Specifically, the metal shell 101 and the first transmission line resonator, the second transmission line resonator, the third transmission line resonator, the fourth transmission line resonator, the fifth transmission line resonator and the sixth transmission line resonator form a micro-coaxial structure. The first transmission line resonator, the second transmission line resonator, the third transmission line resonator, the fourth transmission line resonator, the fifth transmission line resonator and the sixth transmission line resonator form a quarter-wavelength transmission line resonator structure, and the coupling path can be represented by Figure 6The first transmission line resonator is denoted by serial number 1, the second transmission line resonator is denoted by serial number 2, the third transmission line resonator is denoted by serial number 3, the fourth transmission line resonator is denoted by serial number 4, the fifth transmission line resonator is denoted by serial number 5, the sixth transmission line resonator is denoted by serial number 6, the input coupling structure is denoted by S, and the output coupling structure is denoted by L.

[0050] The input feeding structure is arranged on one side of the first transmission line resonator and is used to generate an excitation signal on the first transmission line resonator.

[0051] The output feeding structure is arranged at one side of the sixth transmission line resonator and is used for coupling the signal on the sixth transmission line resonator.

[0052] The source-load coupling structure is arranged between the input feeding structure and the output feeding structure, and is used to introduce source-load coupling. The first adapter structure and the second adapter structure are both micro-coaxial line-coplanar waveguide structures, which are used to connect to peripheral equipment. The first adapter structure and the second adapter structure are respectively arranged on opposite sides of the metal shell 101, and the first adapter structure is connected to the input feeding structure, and the second adapter structure is connected to the output feeding structure.

[0053] As a further refinement of this embodiment, specifically, the first transmission line resonator exists in the form of a first metal inner core 201, and one end of the first metal inner core 201 is fixedly connected to the middle of the inner side surface of the metal shell 101 to achieve a short circuit, and the other end is suspended to achieve an open circuit, and there is a preset gap between the upper and lower side surfaces of the first metal inner core 201 and the inner surface of the metal shell 101. The second transmission line resonator exists in the form of a second metal inner core 202, and the second metal inner core 202 is arranged on one side of the first metal inner core 201 and is parallel to the first metal inner core 201, and one end of the second metal inner core 202 is fixedly connected to the middle of the inner side surface of the metal shell 101 to achieve a short circuit, and the other end is suspended. The third transmission line resonator exists in the form of a third metal inner core 203. The third metal inner core 203 is arranged on a side of the second metal inner core 202 away from the first metal inner core 201 and is parallel to the second metal inner core 202. One end of the third metal inner core 203 is fixedly connected to the middle of the column to realize a short circuit, and the other end is suspended and has a preset distance from the metal shell 101 to realize an open circuit. The upper and lower side surfaces of the third metal inner core 203 have a preset gap with the inner surface of the metal shell 101, and the upper and lower surfaces of the column are fixedly connected to the inner surface of the metal shell 101 respectively.

[0054] Specifically, if the length of the metal shell 101 is defined as being along the X-axis direction and the width of the metal shell 101 is defined as being along the Y-axis direction, and an auxiliary plane is defined as being parallel to the Y-axis and passing through half the length of the metal shell 101, then the structures of the first transmission line resonator and the sixth transmission line resonator, the second transmission line resonator and the fifth transmission line resonator, and the third transmission line resonator and the sixth transmission line resonator are symmetrical relative to the auxiliary plane.

[0055] The sixth transmission line resonator exists in the form of a sixth metal inner core 206, and one end of the sixth metal inner core 206 is fixedly connected to the middle of the inner side surface of the metal shell 101 to achieve a short circuit, and the other end is suspended to achieve an open circuit. There is a preset gap between the upper and lower sides of the sixth metal inner core 206 and the inner surface of the metal shell 101. The fifth transmission line resonator exists in the form of a fifth metal inner core 205. The fifth metal inner core 205 is arranged on one side of the fifth metal inner core 205, and one end of the fifth metal inner core 205 is fixedly connected to the middle of the inner side surface of the metal shell 101. The fifth metal inner core 205 is connected to the middle of the column to achieve a short circuit, and the other end is suspended to achieve an open circuit. A preset gap is formed between the upper and lower side surfaces of the fifth metal inner core 205 and the inner surface of the metal shell 101. The fourth transmission line resonator exists in the form of a fourth metal inner core 204. The fourth metal inner core 204 is arranged opposite to the third metal inner core 202, and one end of the fourth metal inner core 204 is fixedly connected to the middle of the column to achieve a short circuit, and the other end is suspended and has a preset distance from the metal shell 101 to achieve an open circuit. A preset gap is formed between the upper and lower side surfaces of the fourth metal inner core 204 and the inner surface of the metal shell 101.

[0056] Specifically, the input feeding structure includes a seventh metal inner core 207 disposed on a side of the first metal inner core 201 away from the second metal inner core 202 , and an eighth gap 508 for generating excitation is disposed between the seventh metal inner core 207 and the first metal inner core 201 .

[0057] As a detailed implementation, the cross-section of seventh metal core 207 includes Plate 1, Plate 2, and Plate 3, connected end-to-end. Plate 1 and Plate 3 are arranged in parallel, with Plate 1 parallel to first metal core 201, Plate 2 perpendicular to Plate 1, Plate 1 longer than Plate 3, and positioned closer to first metal core 201. The curved structure of seventh metal core 207, formed by Plates 1, 2, and 3, serves as an input feeder.

[0058] Specifically, the output feeding structure includes an eighth metal core 208 arranged on a side of the sixth metal core 206 away from the fifth metal core 205, the eighth metal core 208 and the seventh metal core 207 are symmetrical with respect to the above-mentioned auxiliary plane, and a ninth gap 509 for generating excitation is provided between the eighth metal core 208 and the sixth metal core 206.

[0059] Among them, the cross-section of the eighth metal core 208 includes plate body four, plate body five and plate body six connected end to end in sequence, plate body four and plate body six are arranged in parallel, and plate body five is perpendicular to plate body four, and plate body four is parallel to the sixth metal core 206, plate body four is longer than plate body six, and plate body four is arranged close to the sixth metal core 206. The eighth metal core 208 with a bent structure composed of plate body four, plate body five and plate body six is ​​used as an output feeder.

[0060] Among them, the seventh metal inner core 207 and the eighth metal inner core 208 are in contact with the inner wall of the metal shell 101 to form a grounding structure, which functions to form a short-circuited parallel coupling line structure with the first metal inner core 201 and the sixth metal inner core 206, and to excite the first transmission line resonator and the sixth transmission line resonator through the eighth slot 508 and the ninth slot 509. The above together constitute the input feeding structure and the output feeding structure of the filter.

[0061] A source-load coupling structure is arranged between the input feeding structure and the output feeding structure, and is used to introduce source-load coupling. Specifically, the source-load coupling structure includes a first metal wall 108 arranged between the seventh metal core 207 and the eighth metal core 208. The upper surface and the lower surface of the first metal wall 108 are respectively fixedly connected to the metal shell 101. A fourth gap 504 is opened on the first metal wall 108 to introduce source-load coupling. The source-load coupling can introduce two additional transmission zeros for the filter, thereby enhancing the frequency band selectivity of the filter.

[0062] Furthermore, the position of the transmission zero point of the filter introduced by source-load coupling can be adjusted by adjusting the position and length of the fourth slot 504 .

[0063] The first adapter structure and the second adapter structure are used to connect to peripheral equipment to enhance mechanical stability.

[0064] Among them, such as Figures 1 to 3 As shown, the first transition structure includes a first epitaxial cavity 102 arranged on one side of the metal shell 101. The height of the first epitaxial cavity 102 is lower than the height of the metal shell 101, and a first groove 506 is opened on the upper surface of the first epitaxial cavity 102. A ninth metal core 209 connected to the seventh metal core 207 is arranged in the first groove 506. The upper surface of the ninth metal core 209 is flush with the top surface of the cavity of the first epitaxial cavity 102, serving as the inner conductor of the first transition structure.

[0065] Among them, such as Figures 1 to 3As shown, the second transition structure includes a second epitaxial cavity 103 arranged on the other opposite side of the metal shell 101, the height of the second epitaxial cavity 103 is lower than the height of the metal shell 101 and is flush with the first epitaxial cavity 102, and a second groove 507 is opened on the upper surface of the second epitaxial cavity 103, and a tenth metal core 210 connected to the eighth metal core 208 is arranged in the second groove 507, and the upper surface of the tenth metal core 210 is flush with the top surface of the cavity of the second epitaxial cavity 103, serving as the inner conductor of the second transition structure.

[0066] As a further improvement scheme based on this embodiment, in order to provide support for the inner conductors of the first adapter structure and the second adapter structure respectively, so that the filter can withstand the downward pressure of the probe and the wrench without breaking during the testing and bonding process, as shown in FIG. Figure 3 As shown, a first metal support block 104 is disposed below the end of the ninth metal core 209 away from the metal housing 101. The upper surface of the first metal support block 104 is fixedly connected to the ninth metal core 209. A first step block 105 is disposed below the first metal support block 104 and is fixedly connected to the first epitaxial cavity 102. A second metal support block 106 is disposed below the end of the tenth metal core 210 away from the metal housing 101. The upper surface of the second metal support block 106 is fixedly connected to the tenth metal core 210. A second step block 107 is disposed below the second metal support block 106 and is fixedly connected to the second epitaxial cavity 103. The ninth and tenth metal cores 209 and 210 are connected to the seventh and eighth metal cores 207 and 208, respectively, at their ends closer to the metal housing 101 to feed the filter.

[0067] As a further improvement scheme based on this embodiment, in order to realize the positioning function of the first metal inner core 201, the second metal inner core 202, the third metal inner core 203, the fourth metal inner core 204, the fifth metal inner core 205, the sixth metal inner core 206, the seventh metal inner core 207, the eighth metal inner core 208, the ninth metal inner core 209 and the tenth metal inner core 210, dielectric support strips are respectively provided on them.

[0068] Specifically, in order to realize the positioning function of the ninth metal core 209, a first dielectric support bar 401, a second dielectric support bar 402 and a third dielectric support bar 403 are passed through the ninth metal core 209, and a pair of side surfaces of the first dielectric support bar 401, the second dielectric support bar 402 and the third dielectric support bar 403 are respectively fixedly connected to the first epitaxial cavity 102, for connecting the ninth metal core 209 and the first epitaxial cavity 102 to achieve accurate positioning.

[0069] As a further improvement scheme based on this embodiment, in order to realize the positioning function of the tenth metal inner core 210, a fourth dielectric support bar 404, a fifth dielectric support bar 405 and a sixth dielectric support bar 406 are passed through the tenth metal inner core 210, and a pair of side surfaces of the fourth dielectric support bar 404, the fifth dielectric support bar 405 and the sixth dielectric support bar 406 are respectively fixedly connected to the second epitaxial cavity 103, and are used to connect the tenth metal inner core 210 and the second epitaxial cavity 103 to achieve accurate positioning.

[0070] As a further improvement scheme based on this embodiment, in order to realize the positioning function of the seventh metal core 207, a ninth dielectric support bar 409, an eleventh dielectric support bar 411 and a thirteenth dielectric support bar 413 are passed through the seventh metal core 207, and a pair of side surfaces of the ninth dielectric support bar 409, the eleventh dielectric support bar 411 and the thirteenth dielectric support bar 413 are respectively fixed to a pair of inner walls of the metal shell 101 to improve the stability of the support for the seventh metal core 207.

[0071] As a further improvement scheme based on this embodiment, in order to realize the positioning function of the eighth metal core 208, the tenth dielectric support bar 410, the twelfth dielectric support bar 412 and the fourteenth dielectric support bar 414 are passed through the eighth metal core 208, and a pair of side surfaces of the tenth dielectric support bar 410, the twelfth dielectric support bar 412 and the fourteenth dielectric support bar 414 are respectively fixed to a pair of inner walls of the metal shell 101 to improve the stability of the support of the eighth metal core 208.

[0072] As a further improvement scheme based on this embodiment, in order to realize the positioning function of the first metal inner core 201, the second metal inner core 202, the third metal inner core 203, the fourth metal inner core 204, the fifth metal inner core 205 and the sixth metal inner core 206, a seventh dielectric support bar 407 and an eighth dielectric support bar 408 are passed through them, and a pair of side surfaces of the seventh dielectric support bar 407 and the eighth dielectric support bar 408 are respectively fixed to a pair of inner walls of the metal shell 101 to improve the stability of the support for the first metal inner core 201, the second metal inner core 202, the third metal inner core 203, the fourth metal inner core 204, the fifth metal inner core 205 and the sixth metal inner core 206.

[0073] For the sake of performance and processing convenience, the filter provided by the present invention is processed by three-dimensional electrochemical additive manufacturing technology. The metal shell 101, the first metal inner core 201, the second metal inner core 202, the third metal inner core 203, the fourth metal inner core 204, the fifth metal inner core 205, the sixth metal inner core 206, the seventh metal inner core 207, the eighth metal inner core 208, the ninth metal inner core 209 and the tenth metal inner core 210 are all made of copper. The first dielectric support bar 401, the second dielectric support bar 402, the third dielectric support bar 403, the fourth dielectric support bar 404, the fifth dielectric support bar 405, the sixth dielectric support bar 206, the seventh dielectric support bar 207, the eighth metal inner core 208, the ninth metal inner core 209 and the tenth metal inner core 210 are all made of copper. The dielectric constant of the support bar 406, the seventh dielectric support bar 407, the eighth dielectric support bar 408, the ninth dielectric support bar 409, the eleventh dielectric support bar 411, the thirteenth dielectric support bar 413, the tenth dielectric support bar 410, the twelfth dielectric support bar 412 and the fourteenth dielectric support bar 414 is 2.85. A miniaturized, high-frequency band selective millimeter wave filter is obtained by processing using electrochemical additive manufacturing technology. In order to release the photoresist used in the manufacturing process, a number of release holes 301 are opened on the metal shell 101. The release holes 301 are used to release the photoresist, and the sizes of all release holes 301 are exactly the same.

[0074] It is important to note that the number of release holes 301 should be neither too many nor too few. Too many will cause electromagnetic leakage, while too few will result in incomplete photoresist removal, resulting in residue. The number should be determined after comprehensive consideration during the design. This process yields high-precision products, enabling integrated design and mass production of the filter while ensuring filter performance.

[0075] As a further optimization solution of this embodiment, a partial metal wall structure is added inside the metal shell 101 to reduce the coupling degree.

[0076] Specifically, such as Figure 1As shown, a second metal wall 109 and a third metal wall 110 are further disposed within the metal shell 101. The ends of the first metal wall 108 are fixedly connected to the inner wall and the column of the metal shell 101, respectively. A third slit 503 is defined in the middle of the first metal wall 108, located between the open ends of the second metal core 202 and the fifth metal core 205. The third metal wall 110 and the second metal wall 109 are disposed parallel to each other. The first metal wall 108 extends through the middle of the second and third metal walls 109, 110, and is perpendicular to the third and third metal walls 110 and 109. A pair of side surfaces of the first, second, and third metal walls 108, 109, and 110 are fixedly connected to a pair of inner surfaces of the metal shell 101, respectively. It should be noted that the second metal wall 109 is located between the first and second metal cores 201, 202, and the third metal wall 110 is located between the second and third metal cores 202, 203.

[0077] Among them, such as Figure 5 and Figure 6As shown, the magnetic coupling between the first transmission line resonator and the second transmission line resonator is realized by the first transmission line resonator, the second transmission line resonator, the first gap 501 and the second metal wall 109 inside the metal shell 101, the magnetic coupling between the second transmission line resonator and the third transmission line resonator is realized by the third transmission line resonator, the second transmission line resonator, the second gap 502 and the third metal wall 110, the fifth gap 505 and the second gap 502 provide energy exchange between resonators, and the second metal wall 109 and the third metal wall 110 can appropriately reduce the coupling between resonators by using the high isolation characteristics of the micro coaxial line to adapt to the application requirements of the narrowband filter. When the length of the second metal wall 109 decreases, the magnetic coupling between the first transmission line resonator and the second transmission line resonator increases, and when the second metal wall 109 does not exist, the magnetic coupling and the electric coupling between the first transmission line resonator and the second transmission line resonator will affect each other, which is not conducive to flexible regulation. When the length of the third metal wall 110 decreases, the coupling between the second transmission line resonator and the third transmission line resonator increases, and when the third metal wall 110 does not exist, the coupling between the second transmission line resonator and the third transmission line resonator reaches the maximum under the condition that the width of the fifth gap 505 is unchanged. The magnetic coupling between the third transmission line resonator and the fourth transmission line resonator is realized by the third transmission line resonator, the fourth transmission line resonator and the first gap 501 inside the metal shell 101, and the cross-coupling between the second transmission line resonator and the fifth transmission line resonator is realized by the gap between the open end of the second transmission line resonator and the fifth transmission line resonator and the third gap 503 on the first metal wall 108. Because of the symmetry, the realization of the magnetic coupling between the fourth transmission line resonator and the fifth transmission line resonator is the same as the realization of the magnetic coupling between the second transmission line resonator and the third transmission line resonator, and the realization of the magnetic coupling between the fifth transmission line resonator and the sixth transmission line resonator is the same as the realization of the magnetic coupling between the first transmission line resonator and the second transmission line resonator.

[0078] The overall size of the filter in the specific embodiment is 4.22mm*2.829mm*0.9mm, and after simulation design experiments, as shown in the table, the 3dB passband range of the filter is 91.7GHz-96.3GHz, the minimum insertion loss in the band is 2.03dB, the return loss is better than -18dB, and there is one zero point at 84.8GHz, 90.99GHz, 97GHz and 101.7GHz respectively, which significantly improves the frequency band selectivity of the filter. Figure 7

[0079] ​Compared with existing technologies, the technology proposed in the present invention is the first to propose a filter composed of micro-coaxial line resonators with source-load coupling, introducing additional transmission zeros for the filter, and is the first to propose a resonator coupling structure suitable for narrowband applications, so that the filter has miniaturization characteristics under narrow working bandwidth.

[0080] The micro-coaxial millimeter-wave filter with source-load coupling provided by the present invention can introduce more transmission zeros in combination with source-load coupling, further improving the frequency band selectivity of the filter without excessive use of cross-coupling. It has the advantages of simple structure, small size, and good frequency band selectivity, which is conducive to system miniaturization and improved integration, and improves the reliability of the filter. It can also meet the narrow bandwidth application requirements of higher frequency bands and strict size restrictions, and can well adapt to the high integration requirements of millimeter-wave systems.

[0081] The above disclosure is only a preferred specific embodiment of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A micro-coaxial millimeter wave filter with source-load coupling, characterized in that: include: Metal housing (101); The first transmission line resonator, the second transmission line resonator, the third transmission line resonator, the fourth transmission line resonator, the fifth transmission line resonator and the sixth transmission line resonator are located in the metal shell (101) and are all quarter-wavelength transmission line resonators. The first transmission line resonator and the sixth transmission line resonator, the second transmission line resonator and the fifth transmission line resonator, and the third transmission line resonator and the fourth transmission line resonator are all symmetrically arranged relative to the center of the metal shell (101). The first transmission line resonator and the second transmission line resonator, the second transmission line resonator and the third transmission line resonator, the third transmission line resonator and the fourth transmission line resonator, the fourth transmission line resonator and the fifth transmission line resonator, and the fifth transmission line resonator and the sixth transmission line resonator are magnetically coupled, and the second transmission line resonator and the fifth transmission line resonator are electrically coupled. an input feed structure for generating an excitation signal on the first transmission line resonator; an output feeding structure for coupling a signal on the sixth transmission line resonator; A source-load coupling structure comprises a first metal wall (108) and a fourth slit (504), wherein the first metal wall (108) is arranged between the input feeding structure and the output feeding structure, the upper surface and the lower surface of the first metal wall (108) are respectively fixedly connected to the metal shell (101), and the fourth slit (504) is opened on the first metal wall (108); The first adapter structure and the second adapter structure are respectively used to connect to external equipment. The first adapter structure is connected to the input feed structure, and the second adapter structure is connected to the output feed structure.

2. The micro-coaxial millimeter wave filter with source-load coupling according to claim 1, characterized in that: The first transmission line resonator comprises a first metal inner core (201) with one end open-circuited and the other end short-circuited connected to the metal shell (101); the second transmission line resonator comprises a second metal inner core (202) with one end open-circuited and the other end short-circuited connected to the metal shell (101); the second metal inner core (202) is arranged on one side of the first metal inner core (201) and is parallel to the first metal inner core (201); the third transmission line resonator comprises a third metal inner core (203) with one end open-circuited and the other end short-circuited connected to the metal shell (101); the third metal inner core (203) is arranged on a side of the second metal inner core (202) away from the first metal inner core (201) and is parallel to the second metal inner core (202); One end of the metal inner core (203) is connected to the column to achieve a short circuit, and the upper surface and the lower surface of the column are respectively fixedly connected to the inner surface of the metal shell (101). The sixth transmission line resonator includes a sixth metal inner core (206) with one end open-circuited and the other end short-circuited connected to the metal shell (101). The fifth transmission line resonator includes a fifth metal inner core (205) with one end open-circuited and the other end short-circuited connected to the metal shell (101). The fourth transmission line resonator includes a fourth metal inner core (204) with one end open-circuited and the other end short-circuited connected to the metal shell (101). The fourth metal inner core (204) is arranged opposite to the third metal inner core (202), and one end of the fourth metal inner core (204) is fixedly connected to the middle of the column to achieve a short circuit.

3. The micro-coaxial millimeter-wave filter with source-load coupling according to claim 2, characterized in that: The two ends of the first metal wall (108) are fixedly connected to the inner wall and the column of the metal shell (101), respectively. A third slit (503) is provided in the middle of the first metal wall (108), and the third slit (503) is located on the side of the open end of the second metal inner core (202). The metal shell (101) is further provided with a second metal wall (109) and a third metal wall (110) arranged in parallel. The first metal wall (108) is provided through the second metal wall (109) and the third metal wall (110). 10) and is perpendicular to the third metal wall (110) and the second metal wall (109), and a pair of side surfaces of the first metal wall (108), the second metal wall (109) and the third metal wall (110) are respectively fixedly connected to a pair of inner surfaces of the metal shell (101), the second metal wall (109) is located between the first metal inner core (201) and the second metal inner core (202), and the third metal wall (110) is located between the second metal inner core (202) and the third metal inner core (203).

4. The micro-coaxial millimeter wave filter with source-load coupling according to claim 2, characterized in that: The input feed structure comprises: a seventh metal inner core (207) disposed on a side of the first metal inner core (201) away from the second metal inner core (202), wherein the seventh metal inner core (207) contacts the inner wall of the metal shell (101) to form a grounding structure; An eighth gap (508), used for generating excitation, is provided between the seventh metal inner core (207) and the first metal inner core (201).

5. The micro-coaxial millimeter wave filter with source-load coupling according to claim 4, characterized in that: The output feeding structure comprises: an eighth metal inner core (208) disposed on a side of the sixth metal inner core (206) away from the fifth metal inner core (205), wherein the eighth metal inner core (208) contacts the inner wall of the metal shell (101) to form a grounding structure; A ninth gap (509), used for generating excitation, is provided between the eighth metal inner core (208) and the sixth metal inner core (206).

6. The micro-coaxial millimeter-wave filter with source-load coupling according to claim 5, characterized in that: The first switching structure includes: A first epitaxial cavity (102) is provided on a side surface of the metal shell (101), wherein the height of the first epitaxial cavity (102) is lower than the height of the metal shell (101), and a first groove (506) is provided on the upper surface of the first epitaxial cavity (102); a ninth metal inner core (209) disposed in the first groove (506) and connected to the seventh metal inner core (207), wherein the upper surface of the ninth metal inner core (209) is flush with the top surface of the first epitaxial cavity (102); a first metal support block (104) disposed below an end of the ninth metal inner core (209) away from the metal shell (101), wherein the upper surface of the first metal support block (104) is fixedly connected to the ninth metal inner core (209); The first step block (105) is arranged below the first metal support block (104), and the first step block (105) is fixedly connected to the first epitaxial cavity (102).

7. The micro-coaxial millimeter wave filter with source-load coupling according to claim 6, characterized in that: The second switching structure includes: a second epitaxial cavity (103) disposed on another opposite side of the metal shell (101); the height of the second epitaxial cavity (103) is lower than the height of the metal shell (101) and is flush with the first epitaxial cavity (102); and a second groove (507) is formed on the upper surface of the second epitaxial cavity (103); a tenth metal inner core (210) disposed in the second groove (507) and connected to the eighth metal inner core (208), wherein the upper surface of the tenth metal inner core (210) is flush with the top surface of the second epitaxial cavity (103); a second metal support block (106) disposed below an end of the tenth metal inner core (210) away from the metal shell (101), wherein the upper surface of the second metal support block (106) is fixedly connected to the tenth metal inner core (210); The second step block (107) is arranged below the second metal support block (106), and the second step block (107) is fixedly connected to the second epitaxial cavity (103).

8. The micro-coaxial millimeter wave filter with source-load coupling according to claim 7, characterized in that: The first metal inner core (201), the second metal inner core (202), the third metal inner core (203), the fourth metal inner core (204), the fifth metal inner core (205), the sixth metal inner core (206), the seventh metal inner core (207), the eighth metal inner core (208), the ninth metal inner core (209) and the tenth metal inner core (210) are respectively provided with dielectric support strips.

9. The micro-coaxial millimeter-wave filter with source-load coupling according to any one of claims 1 to 8, characterized in that: A plurality of release holes (301) are provided on the surface of the metal shell (101), and the release holes (301) are used for releasing photoresist.

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