Band-pass filter

Abstract

According to the band-pass filter provided by the invention, a first metal layer of a quarter-mode substrate integrated waveguide comprises a circular quarter-mode waveguide pattern which is used for forming artificial surface plasmon polaritons; the first surface of the dielectric substrate is also provided with an input structure and an output structure which are symmetrically arranged, and a first transition structure and a second transition structure which are symmetrically arranged, and the first transition structure is connected between the input structure and the circular quarter-mode waveguide pattern. The first transition structure is connected between the input structure and the circular quarter-mode waveguide pattern to enable smooth transition between the input structure and the circular quarter-mode waveguide pattern, and the second transition structure is connected between the output structure and the circular quarter-mode waveguide pattern to enable smooth transition between the input structure and the circular quarter-mode waveguide pattern. And the first transition structure and the second transition structure are matched with the artificial surface plasmon polaritons. The SSPP band-pass filter is realized in the quarter-mode substrate integrated waveguide, and has the advantages of ultra-wide stop band, easy integration, compact structure and low cost.

Description

Technical Field

[0001] The disclosed embodiments of the present application relate to the field of wireless communication technology, and more specifically, to a bandpass filter. Background Art

[0002] In recent years, with the rapid development of wireless communication technology, the performance and functional requirements of RF circuits have been continuously improved. As a key component of the communication system, RF circuits need to achieve higher performance and more diverse functions to meet the various communication needs of various industries. Among them, bandpass filters, as a frequency selection device, are widely used in various communications, radars, and test systems. They play an important role in selecting the required frequency signal while filtering out interference signals of other frequencies. The performance of the filter directly affects the performance of the entire wireless communication system.

[0003] In addition, with the emergence of new wireless communication systems such as 6G communication, various design requirements of filters have brought unprecedented challenges. On the premise of ensuring high performance, how to achieve the miniaturization of filters to reduce costs, improve passband frequency selectivity, widen the filter stopband bandwidth and enhance anti-interference ability has become a hot spot in current filter research and design. Summary of the invention

[0004] According to an embodiment of the present application, the present application proposes a bandpass filter to solve the above-mentioned problem.

[0005] According to aspects of the present application, an exemplary bandpass filter is disclosed, comprising a dielectric substrate, on which a quarter-mode substrate integrated waveguide is disposed, the quarter-mode substrate integrated waveguide comprising: a first metal layer, disposed on a first surface of the dielectric substrate, comprising a circular quarter-mode waveguide pattern, wherein the circular quarter-mode waveguide pattern is used to form an artificial surface plasmon; a second metal layer, disposed on a second surface of the dielectric substrate, wherein the second surface is disposed opposite to the first surface; and a metal through hole, connected to the first metal layer and the second metal layer; wherein a symmetrically disposed input structure and an output structure and a symmetrically disposed first transition structure and a second transition structure are also disposed on the first surface of the dielectric substrate, wherein the first transition structure is connected between the input structure and the circular quarter-mode waveguide pattern to enable a smooth transition between the input structure and the circular quarter-mode waveguide pattern, and the second transition structure is connected between the output structure and the circular quarter-mode waveguide pattern to enable a smooth transition between the input structure and the circular quarter-mode waveguide pattern, and the first transition structure and the second transition structure are adapted to the artificial surface plasmon.

[0006] In some embodiments, the circular quarter-mode waveguide pattern includes: a first part, wherein the metal through hole is arranged at a circular edge of the first part; a second part, connected to the first part, and the second part is provided with a plurality of grooves along the symmetric direction of the input structure and the output structure or the first transition structure and the second transition structure to form the artificial surface plasmon.

[0007] In some embodiments, the second portion is provided with a plurality of first rectangular slots along the symmetry direction, and the plurality of first rectangular slots are arranged at equal intervals along a direction perpendicular to the symmetry direction to form the artificial surface plasmons.

[0008] In some embodiments, the lengths of the plurality of first rectangular slots along the symmetry direction are the same, and the widths of the plurality of first rectangular slots along a direction perpendicular to the symmetry direction are the same.

[0009] In some embodiments, the circular quarter mode waveguide pattern is symmetrically arranged along the symmetry direction, wherein the first portion and the second portion are both symmetrically arranged along the symmetry direction.

[0010] In some embodiments, the first transition structure is connected to the first portion and the second portion, and the second transition structure is connected to the first portion and the second portion, wherein the first transition structure and the second transition structure are both trapezoidal transition structures, so that the first transition structure is respectively adapted to the circular quarter-mode waveguide pattern along the symmetry direction and a direction perpendicular to the symmetry direction, and the second transition structure is respectively adapted to the circular quarter-mode waveguide pattern along the symmetry direction and a direction perpendicular to the symmetry direction.

[0011] In some embodiments, the first transition structure is provided with a plurality of second rectangular grooves along the symmetry direction, and the plurality of second rectangular grooves are arranged at equal intervals along a direction perpendicular to the symmetry direction, so that the first transition structure is adapted to the second portion of the circular quarter-mode waveguide pattern along the direction perpendicular to the symmetry direction; the second transition structure is provided with a plurality of second rectangular grooves along the symmetry direction, and the plurality of second rectangular grooves are arranged at equal intervals along a direction perpendicular to the symmetry direction, so that the second transition structure is adapted to the second portion of the circular quarter-mode waveguide pattern along the direction perpendicular to the symmetry direction; wherein the second rectangular grooves of the first transition structure and the second rectangular grooves of the second transition structure are symmetrically arranged along the symmetry direction.

[0012] In some embodiments, the lengths of the plurality of the second rectangular grooves of the first transition structure along the symmetry direction increase successively from the input structure or the output structure to the second part, and the widths along the direction perpendicular to the symmetry direction are the same, so that the first transition structure is adapted to the second part along the symmetry direction; the lengths of the plurality of the second rectangular grooves of the second transition structure along the symmetry direction increase successively from the input structure or the output structure to the second part, and the widths along the direction perpendicular to the symmetry direction are the same, so that the second transition structure is adapted to the second part along the symmetry direction.

[0013] In some embodiments, the input structure includes an input feeder and an input loading structure, wherein the input feeder is arranged vertically to the input loading structure; the output structure includes an output feeder and an output loading structure, wherein the output feeder is arranged vertically to the output loading structure; wherein the input feeder is symmetrically arranged to the output feeder, and the input loading structure is symmetrically arranged to the output loading structure.

[0014] In some embodiments, the input loading structure and the output loading structure are both step impedance microstrip lines, including a first microstrip line and a second microstrip line, the first microstrip line is vertically arranged with the input feeder line or the output feeder line, the second microstrip line is connected to the first microstrip line and is horizontally arranged, and the characteristic impedance of the first microstrip line is greater than the characteristic impedance of the second microstrip line.

[0015] The beneficial effects of the present application are as follows: in a bandpass filter, the first metal layer through a quarter-mode substrate integrated waveguide includes a circular quarter-mode waveguide pattern, the circular quarter-mode waveguide pattern is used to form an artificial surface plasmon, and a symmetrically arranged input structure and an output structure and a symmetrically arranged first transition structure and a second transition structure are also arranged on the first surface of the dielectric substrate, wherein the first transition structure is connected between the input structure and the circular quarter-mode waveguide pattern to enable a smooth transition between the input structure and the circular quarter-mode waveguide pattern, the second transition structure is connected between the output structure and the circular quarter-mode waveguide pattern to enable a smooth transition between the input structure and the circular quarter-mode waveguide pattern, and the first transition structure and the second transition structure are adapted to the artificial surface plasmon, so as to realize a bandpass filter that realizes SSPP in a quarter-mode substrate integrated waveguide, and has an ultra-wide stopband, is easy to integrate, has a compact structure, and is low in cost.

[0016] These and other objects of the present application will no doubt become apparent to those skilled in the art after reading the following detailed description of the preferred embodiments illustrated in the figures and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1a is a schematic top view of a bandpass filter according to an embodiment of the present application.

[0018] Figure 1b is a side perspective schematic diagram of a bandpass filter according to an embodiment of the present application.

[0019] Figure 1c is a bottom view schematic diagram of a bandpass filter according to an embodiment of the present application.

[0020] Figure 2a Schematic diagram 1 of the design dimensions of a bandpass filter according to an embodiment of the present application.

[0021] Figure 2b Schematic diagram 2 of the design dimensions of the bandpass filter according to an embodiment of the present application.

[0022] Figure 3a 1 is a scattering parameter curve diagram of the bandpass filter according to an embodiment of the present application.

[0023] Figure 3b Graph 2 of the scattering parameter of the bandpass filter according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The scheme of the embodiment of the present application is described in detail below in conjunction with the drawings of the specification.

[0025] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0026] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the objects associated before and after are in an "or" relationship. In addition, "many" in this article means two or more than two. In addition, the term "at least one" in this article means any combination of at least two of any one or more of a plurality of, for example, including at least one of A, B, and C, can mean including any one or more elements selected from the set consisting of A, B, and C.

[0027] Artificial surface plasmon polaritons (SSPPs) have gradually become a research hotspot due to their strong confinement and slow-wave characteristics. The substrate integrated waveguide (SIW) can realize bandpass filtering function by combining with SSPP with its high-pass characteristics and low-loss characteristics. At present, some typical structures and design methods have been proposed for SSPP bandpass filters based on SIW, such as integrating SSPP structure on SIW to realize bandpass filter, for example, integrating SSPP structure on slotted full-mode SIW, half-mode SIW, and ridged SIW. This structure and design method mainly focuses on the improvement of longitudinal size by reducing lateral size, but this improvement is limited and it is difficult to meet the needs of higher integration.

[0028] like Figure 1a-Figure 1c As shown, it is a schematic diagram of the structure of a bandpass filter 100 according to an embodiment of the present application. The bandpass filter 100 includes a dielectric substrate Su, on which a quarter-mode substrate integrated waveguide (Quarter-Mode SIW, QMSIW) 110 is arranged, and the quarter-mode substrate integrated waveguide 110 includes a first metal layer 111, a second metal layer 112 and a metal through hole 113. The first metal layer 111 is arranged on the first surface of the dielectric substrate Su, including a circular quarter-mode waveguide pattern 1111, wherein the circular quarter-mode waveguide pattern 1111 is used to form an artificial surface plasmon. The second metal layer 112 is arranged on the second surface of the dielectric substrate Su, wherein the second surface is arranged opposite to the first surface. The metal through hole 113 is connected to the first metal layer 111 and the second metal layer 112.

[0029] The quarter-mode substrate integrated waveguide 110 is a substrate integrated waveguide (SIW) whose size, such as its width and length, is reduced to one-fourth of that of a conventional SIW. The quarter-mode substrate integrated waveguide 110 has a circular quarter-mode waveguide pattern 1111, so the quarter-mode substrate integrated waveguide 110 can also be called a circular quarter-mode substrate integrated waveguide. The circular quarter-mode waveguide pattern 1111 on the quarter-mode substrate integrated waveguide 110 is used to form artificial surface plasmon polaritons (SSPPs) and has the low-pass characteristic of SSPP. Moreover, the circular quarter-mode waveguide pattern 1111 on the quarter-mode substrate integrated waveguide 110 itself is used to realize a quarter-mode waveguide and has a high-pass characteristic. In other words, SSPP is realized inside the quarter-mode substrate integrated waveguide 110, rather than being integrated with SSPP outside the quarter-mode substrate integrated waveguide 110. The circular quarter-mode waveguide pattern 1111 may also be referred to as a circular quarter-mode waveguide structure, ie, a waveguide structure on the quarter-mode substrate integrated waveguide 110 .

[0030] The first surface of the dielectric substrate Su may be the upper surface of the dielectric substrate Su, and the second surface of the dielectric substrate Su may be the lower surface of the dielectric substrate Su. The metal material of the first surface and the second surface of the dielectric substrate Su may be copper, and the copper thickness may be determined according to the actual situation of the specific dielectric substrate Su, for example, it may be 0.035 mm. The first metal layer 111 may also be called a patch metal layer to realize the circular quarter-mode waveguide pattern 1111, and the second metal layer 112 may also be a metal grounding layer to realize grounding. The metal through hole 113 is a conductive metal injected into the through hole, for example, copper, etc. The number of the metal through holes 113 may be determined according to the actual size of the circular quarter-mode waveguide pattern 1111. For example, the diameter d of the metal through hole 113 may be 0.3 mm. Thus, the number of the metal through holes 113 may be determined according to the actual size of the circular quarter-mode waveguide pattern 1111 and the diameter of the metal through hole 113.

[0031] The circular quarter-mode waveguide pattern 1111 uses a portion of a circular metal patch, namely a metal patch in a sector shape.

[0032] Among them, a symmetrically arranged input structure P1 and output structure P2 and a symmetrically arranged first transition structure 120 and a second transition structure 130 are also arranged on the first surface of the dielectric substrate Su, wherein the first transition structure 120 is connected between the input structure P1 and the circular quarter-mode waveguide pattern 1111 to make a smooth transition between the input structure P1 and the circular quarter-mode waveguide pattern 1111, and the second transition structure 130 is connected between the output structure P2 and the circular quarter-mode waveguide pattern 1111 to make a smooth transition between the input structure P1 and the circular quarter-mode waveguide pattern 1111, and the first transition structure 120 and the second transition structure 130 are adapted to artificial surface plasmons.

[0033] The input structure P1 and the output structure P2 are used to provide electromagnetic excitation. The quarter-mode substrate integrated waveguide 110 forms a passband under the action of electromagnetic excitation. Since the circular quarter-mode waveguide pattern 1111 is used to form SSPP, the ultra-wide stopband of the bandpass filter 100 is achieved through the strong confinement and low-pass characteristics of SSPP.

[0034] The input structure P1 and the output structure P2 are symmetrically arranged, and the first transition structure 120 and the second transition structure 130 are symmetrically arranged, wherein the symmetric direction of the symmetrical arrangement of the input structure P1 and the output structure P2 is the same as the symmetric direction of the symmetrical arrangement of the first transition structure 120 and the second transition structure 130. For example, Figure 1a-Figure 1c In the embodiment, the symmetry direction is the vertical direction. Of course, the symmetry direction can also be other directions, such as the horizontal direction, which is determined according to the actual design setting of the bandpass filter 100.

[0035] The first transition structure 120 is connected between the input structure P1 and the circular quarter-mode waveguide pattern 1111, that is, one end of the first transition structure 120 is connected to the input structure P1, and the other end is connected to the circular quarter-mode waveguide pattern 1111, so that a smooth transition is made between the input structure P1 and the circular quarter-mode waveguide pattern 1111. The second transition structure 130 is connected between the output structure P2 and the circular quarter-mode waveguide pattern 1111, that is, one end of the second transition structure 130 is connected to the output structure P2, and the other end is connected to the circular quarter-mode waveguide pattern 1111, so that a smooth transition is made between the output structure P2 and the circular quarter-mode waveguide pattern 1111.

[0036] The first transition structure 120 allows a smooth transition between the input structure P1 and the circular quarter-mode waveguide pattern 1111, so that the first transition structure 120 achieves impedance matching between the input structure P1 and the circular quarter-mode waveguide pattern 1111, and the first transition structure 120 is adapted to the artificial surface plasmon, so that the impedance matching between the first transition structure 120 and the SSPP is achieved. The second transition structure 130 allows a smooth transition between the output structure P2 and the circular quarter-mode waveguide pattern 1111, so that the second transition structure 130 achieves impedance matching between the input structure P1 and the circular quarter-mode waveguide pattern 1111, and the second transition structure 130 is adapted to the artificial surface plasmon, so that the impedance matching between the second transition structure 130 and the SSPP is achieved.

[0037] It should be noted that the first transition structure 120 and the second transition structure 130 may be expressed interchangeably, that is, the first transition structure 120 may also be the second transition structure 130 , and the second transition structure 130 may also be the first transition structure 120 .

[0038] In this embodiment, in the bandpass filter 100, the first metal layer 111 of the quarter-mode substrate integrated waveguide 110 includes a circular quarter-mode waveguide pattern 1111, and the circular quarter-mode waveguide pattern 1111 is used to form an artificial surface plasmon. A symmetrically arranged input structure P1 and an output structure P2 and a symmetrically arranged first transition structure 120 and a second transition structure 130 are also arranged on the first surface of the dielectric substrate Su, wherein the first transition structure 120 is connected between the input structure P1 and the circular quarter-mode waveguide pattern 1111, so that A smooth transition is obtained between the input structure P1 and the circular quarter-mode waveguide pattern 1111, and the second transition structure 130 is connected between the output structure P2 and the circular quarter-mode waveguide pattern 1111, so that a smooth transition is obtained between the input structure P1 and the circular quarter-mode waveguide pattern 1111, and the first transition structure 120 and the second transition structure 130 are adapted to the artificial surface plasmon polaritons, so as to realize the bandpass filter 100 of SSPP in the quarter-mode substrate integrated waveguide 110, which has an ultra-wide stopband, is easy to integrate, has a compact and miniaturized structure, and is low in cost.

[0039] As described above, the first metal layer 111 includes a circular quarter-mode waveguide pattern 1111. In some embodiments, the circular quarter-mode waveguide pattern 1111 includes: a first portion 1111a, wherein a metal through hole 113 is disposed at a circular edge of the first portion 1111a; a second portion 1111b, connected to the first portion 1111a, and the second portion 1111b is provided with a plurality of grooves g1 along the symmetric direction of the input structure P1 and the output structure P2 or the first transition structure 120 and the second transition structure 130 to form artificial surface plasmons.

[0040] The first portion 1111a of the circular quarter mode waveguide pattern 1111 is approximately fan-shaped, and the second portion 1111b is approximately rectangular. The first portion 1111a and the second portion 1111b are connected to form a fan-shaped shape, wherein the second portion 1111b is located below the first portion 1111a and close to the center of the fan-shaped shape.

[0041] The second portion 1111b is provided with a plurality of slots g1, which extend along a symmetric direction to form artificial surface plasmons. The number of the slots g1 is Figure 1a-Figure 1c In the embodiment, there are 3 slots g1. Of course, in other embodiments, the number of slots g1 can be set according to actual design requirements.

[0042] The shapes and sizes of the grooves g1 can be the same. For example, all the grooves g1 can have the same shape and size, or the shapes and sizes of the grooves g1 symmetrically arranged about the symmetry direction can be the same. In other words, the shapes and sizes of the symmetrically arranged grooves g1 are the same, and if there are remaining grooves g1, the shapes and sizes of the remaining grooves g1 are different from those of the symmetrically arranged grooves g1.

[0043] Furthermore, in some embodiments, the second portion 1111b is provided with a plurality of first rectangular slots g1 along a symmetric direction, and the plurality of first rectangular slots g1 are arranged at equal intervals along a direction perpendicular to the symmetric direction to form artificial surface plasmons.

[0044] The first rectangular slot g1 extends along the symmetry direction. In the example where the symmetry direction is the vertical direction, as shown in FIG. Figure 1a-Figure 1c As shown, each first rectangular slot g1 extends along the vertical direction, and a plurality of first rectangular slots g1 are arranged at equal intervals along the horizontal direction to form artificial surface plasmons. For example, the intervals between the plurality of first rectangular slots g1 along the horizontal direction can be set to 1.2 mm.

[0045] In some embodiments, the lengths of the plurality of first rectangular slots g1 along the symmetry direction are the same, and the widths along the direction perpendicular to the symmetry direction are the same.

[0046] That is to say, all the first rectangular slots g1 have the same shape, ie, a rectangle, and the same size.

[0047] In some embodiments, continuing as Figure 1a-1c As shown, the circular quarter mode waveguide pattern 1111 is symmetrically arranged along the symmetry direction, wherein the first portion 1111a and the second portion 1111b are both symmetrically arranged along the symmetry direction.

[0048] In the example where the symmetry direction is the vertical direction, the circular quarter mode waveguide pattern 1111 is a symmetrical structure along the vertical direction, wherein the first portion 1111a and the second portion 1111b are both symmetrical structures, that is, the first portion 1111a and the second portion 1111b are symmetrical about the vertical direction.

[0049] The circular quarter mode waveguide pattern 1111 is symmetrically arranged along the symmetry direction, the input structure P1 and the output structure P2 are symmetrically arranged along the symmetry direction, and the first transition structure 120 and the second transition structure 130 are symmetrically arranged along the symmetry direction, thereby indicating that the bandpass filter 100 is symmetrical about the symmetry direction.

[0050] In some embodiments, Figure 1a-Figure 1c As shown, the first transition structure 120 is connected to the first part 1111a and the second part 1111b, and the second transition structure 130 is connected to the first part 1111a and the second part 1111b, wherein the first transition structure 120 and the second transition structure 130 are both trapezoidal transition structures, so that the first transition structure 120 is respectively adapted to the circular quarter-mode waveguide pattern 1111 along the symmetric direction and the direction perpendicular to the symmetric direction, and the second transition structure 130 is respectively adapted to the circular quarter-mode waveguide pattern 1111 along the symmetric direction and the direction perpendicular to the symmetric direction.

[0051] like Figure 1a-Figure 1c As shown, both the first transition structure 120 and the second transition structure 130 are trapezoidal transition structures, which are trapezoidal in shape and have two right angles, and the two right angles are located in the same symmetric direction. The first transition structure 120 is connected to the first part 1111a through a right angle side of the upper right angle, and the other right angle side is connected to the second part 1111b. Similarly, the second transition structure 130 is connected to the first part 1111a through a right angle side of the upper right angle, and the other right angle side is connected to the second part 1111b.

[0052] The first transition structure 120 is connected to the first portion 1111a via one right-angled side of an upper right angle, and the other right-angled side is connected to the second portion 1111b, so that the first transition structure 120 is adapted to the circular quarter-mode waveguide pattern 1111 along the symmetric direction and the direction perpendicular to the symmetric direction, respectively. That is, the first transition structure 120 achieves matching with the first portion 1111a of the circular quarter-mode waveguide pattern 1111 and matching with the second portion 1111b of the circular quarter-mode waveguide pattern 1111. The second transition structure 130 is connected to the first portion 1111a via one right-angled side of an upper right angle, and the other right-angled side is connected to the second portion 1111b, so that the second transition structure 130 is adapted to the circular quarter-mode waveguide pattern 1111 along the symmetric direction and the direction perpendicular to the symmetric direction, respectively. That is, the second transition structure 130 achieves matching with the first portion 1111a of the circular quarter-mode waveguide pattern 1111 and matching with the second portion 1111b of the circular quarter-mode waveguide pattern 1111.

[0053] As described above, the first transition structure 120 is adapted to the circular quarter-mode waveguide pattern 1111 along the direction perpendicular to the symmetry direction, and the second transition structure 130 is adapted to the circular quarter-mode waveguide pattern 1111 along the direction perpendicular to the symmetry direction. In some embodiments, the first transition structure 120 is provided with a plurality of second rectangular slots g2 along the symmetry direction, and the plurality of second rectangular slots g2 are arranged at equal intervals along the direction perpendicular to the symmetry direction, so that the first transition structure 120 is adapted to the second portion 1111b of the circular quarter-mode waveguide pattern 1111 along the direction perpendicular to the symmetry direction; the second transition structure 130 is provided with a plurality of second rectangular slots g2 along the symmetry direction, and the plurality of second rectangular slots g2 are arranged at equal intervals along the direction perpendicular to the symmetry direction, so that the second transition structure 130 is adapted to the second portion 1111b of the circular quarter-mode waveguide pattern 1111 along the direction perpendicular to the symmetry direction; wherein the second rectangular slots g2 of the first transition structure 120 and the second rectangular slots g2 of the second transition structure 130 are arranged symmetrically along the symmetry direction.

[0054] The second rectangular slot g2 extends along the symmetric direction. Figure 1a-Figure 1cAs shown, in an example where the symmetric direction is the vertical direction, on the first transition structure 120, each second rectangular slot g2 extends along the vertical direction, and a plurality of second rectangular slots g2 are arranged at equal intervals along the horizontal direction, so that the first transition structure 120 is adapted to the second portion 1111b of the circular quarter-mode waveguide pattern 1111 along the horizontal direction, that is, the second rectangular slot g2 makes the first transition structure 120 match the second portion 1111b. On the second transition structure 130, each second rectangular slot g2 extends along the vertical direction, and a plurality of second rectangular slots g2 are arranged at equal intervals along the horizontal direction, so that the second transition structure 130 is adapted to the second portion 1111b of the circular quarter-mode waveguide pattern 1111 along the horizontal direction, that is, the second rectangular slot g2 makes the second transition structure 130 match the second portion 1111b.

[0055] The intervals between the plurality of second rectangular slots g2 along the horizontal direction are the same as the intervals between the plurality of first rectangular slots g1 along the horizontal direction. For example, the intervals between the plurality of first rectangular slots g1 along the horizontal direction can be set to 1.2 mm, and the intervals between the plurality of first rectangular slots g1 along the horizontal direction can also be set to 1.2 mm.

[0056] As described above, the first transition structure 120 is adapted to the circular quarter-mode waveguide pattern 1111 along the symmetric direction, and the second transition structure 130 is adapted to the circular quarter-mode waveguide pattern 1111 along the symmetric direction. In some embodiments, the lengths of the plurality of second rectangular slots g2 of the first transition structure 120 along the symmetric direction increase sequentially from the input structure P1 or the output structure P2 to the second portion 1111b, and the widths along the direction perpendicular to the symmetric direction are the same, so that the first transition structure 120 is adapted to the second portion 1111b along the symmetric direction; the lengths of the plurality of second rectangular slots g2 of the second transition structure 130 along the symmetric direction increase sequentially from the input structure P1 or the output structure P2 to the second portion 1111b, and the widths along the direction perpendicular to the symmetric direction are the same, so that the second transition structure 130 is adapted to the second portion 1111b along the symmetric direction.

[0057] As shown in Figure 1- Figure 1c As shown, in an example where the symmetric direction is the vertical direction, on the first transition structure 120, the length of the second rectangular slot g2 along the symmetric direction increases sequentially. For example, the length of the second rectangular slot g2 along the symmetric direction is from the input structure P1 to the second part 1111b, that is, from left to right in the horizontal direction, from h 1 =1mm to h 5 =3mm, step length is 0.5mm, width w 2The length of the second rectangular slot g2 along the symmetric direction increases in sequence on the second transition structure 130. For example, the length of the second rectangular slot g2 along the symmetric direction increases from the output structure P2 to the second part 1111b, that is, from right to left in the horizontal direction, from h 1 =1mm to h 5 =3mm, step length is 0.5mm, width w 2 The second rectangular grooves g2 are 3.5 mm, and the second transition structure 130 is matched with the second portion 1111 b.

[0058] In some embodiments, Figure 1a-1c As shown, the input structure P1 includes an input feeder P11 and an input loading structure P12, wherein the input feeder P11 and the input loading structure P12 are vertically arranged; the output structure P2 includes an output feeder P21 and an output loading structure P22, wherein the output feeder P21 and the output loading structure P22 are vertically arranged; wherein the input feeder P11 and the output feeder P21 are symmetrically arranged, and the input loading structure P12 and the output loading structure P22 are symmetrically arranged.

[0059] The input loading structure P12 and the output loading structure P22 are quarter-wavelength microstrip lines. The input loading structure P12 is set on the input feeder P11, that is, the input loading structure P12 is loaded on the input feeder P11, and the output loading structure P22 is set on the output feeder P21, that is, the output loading structure P22 is loaded on the output feeder P21, which can generate a transmission zero point at the lower cutoff frequency of the passband, thereby improving the frequency selectivity of the passband.

[0060] Furthermore, in some embodiments, Figure 1a-Figure 1c As shown, the input loading structure P12 and the output loading structure P22 are both step impedance microstrip lines, including a first microstrip line P121 or P221 and a second microstrip line P122 or P222, the first microstrip line P121 or P221 is vertically arranged with the input feeder line P11 or the output feeder line P21, the second microstrip line P122 or P222 is connected to the first microstrip line P121 or P221 and is horizontally arranged, and the characteristic impedance of the first microstrip line P121 or P221 is greater than the characteristic impedance of the second microstrip line P122 or P222.

[0061] The input loading structure P12 includes a first microstrip line P121 and a second microstrip line P122, wherein the first microstrip line P121 is vertically arranged with the input feed line P11, and the second microstrip line P122 of the input loading structure P12 is connected with the first microstrip line P121 and is horizontally arranged, and the characteristic impedance of the first microstrip line P121 is greater than the characteristic impedance of the second microstrip line P122. Since the characteristic impedance of the first microstrip line P121 of the input loading structure P12 is greater than the characteristic impedance of the second microstrip line P122, the physical width of the first microstrip line P121 is less than the physical width of the second microstrip line P122.

[0062] The output loading structure P22 includes a first microstrip line P221 and a second microstrip line P222, wherein the first microstrip line P221 is vertically arranged with the output feeder line P21, the second microstrip line P222 of the output loading structure P22 is connected with the first microstrip line P221 and is horizontally arranged, and the characteristic impedance of the first microstrip line P221 is greater than the characteristic impedance of the second microstrip line P222. Since the characteristic impedance of the first microstrip line P221 of the output loading structure P22 is greater than the characteristic impedance of the second microstrip line P222, the physical width of the first microstrip line P221 of the output loading structure P22 is less than the physical width of the second microstrip line P222.

[0063] The characteristic impedance of the first microstrip line P121 of the input loading structure P12 is greater than the characteristic impedance of the second microstrip line P122, and the characteristic impedance of the first microstrip line P221 of the output loading structure P22 is greater than the characteristic impedance of the second microstrip line P222. By adjusting the impedance ratio of the first microstrip line P121 or P221 to the second microstrip line P122 or P222 of the input loading structure P12 and the output loading structure P22, the spurious frequencies of the input loading structure P12 and the output loading structure P22 can be kept away from the passband, thereby improving the upper stopband suppression performance of the bandpass filter 100.

[0064] The bandpass filter 100 of the present application is described below using a design example.

[0065] like Figure 2a-2b As shown, in the bandpass filter 100, the material of the dielectric substrate Su is Rogers 4350, and the relative dielectric constant ε r =3.66, dielectric loss tangent tanδ=0.007, the metal material of the first metal layer 111 and the second metal layer 112 is copper, and its thickness is 0.035 mm.

[0066] The length L of the dielectric substrate Su is 28.84 mm, the width W is 15 mm, and the thickness h t The length l of the input feeder line P11 and the output feeder line P21 on the upper surface 111 of the dielectric substrate Su, that is, on the first metal layer 111, is 1The width w is 4.69 mm. 1 The length of the first transition structure 120 and the second transition structure 130 is l 2 8mm, width w 2 3.5 mm, and five second rectangular slots g2 are provided on the first transition structure 120 and the second transition structure 130, the length of which is from h 1 =1mm to h 5 =3mm, the step length is 0.5mm. The radius R of the circular quarter mode waveguide pattern 1111 is 8mm, the diameter d of the metal through hole 113 is 0.3mm, and three first rectangular slots g1 are arranged on the second part 1111b of the circular quarter mode waveguide pattern 1111, each of which has a width a of 0.4mm and a period p of 1.2mm, that is, an interval p of 1.2mm.

[0067] The first microstrip line w of the input loading structure P12 b 0.4mm, length l 6 is 5 mm, and the width of the second microstrip line w a The diameter is 2.2mm and the length is 2.2mm.

[0068] The upper surface 112 of the dielectric substrate Su, ie, the first metal layer 112, has a length L of 28.84 mm and a width W of 15 mm.

[0069] like Figure 3a and Figure 3b As shown, described Figure 3a-Figure 3b The electromagnetic simulation results of the bandpass filter 100 are shown. It can be seen that the center frequency of the bandpass filter 100 is 8.95 GHz, the operating frequency range is 5.5 to 12.4 GHz, the stopband bandwidth of the bandpass filter 100 reaches 150 GHz, the stopband suppression level is better than -20 dB, and an ultra-wide stopband characteristic is achieved. At the same time, there is a transmission zero point at the lower cutoff frequency of the passband, achieving high selectivity of the passband.

[0070] It is easy for a person skilled in the art to know that many modifications and changes can be made to the device and method while maintaining the teaching content of the present application. Therefore, the above disclosure should be considered as limited only by the scope of the appended claims.

Claims

1. A bandpass filter, characterized in that: The invention comprises a dielectric substrate, on which a quarter-mode substrate integrated waveguide is arranged, and the quarter-mode substrate integrated waveguide comprises: A first metal layer is disposed on the first surface of the dielectric substrate and includes a circular quarter-mode waveguide pattern, wherein the circular quarter-mode waveguide pattern is used to form an artificial surface plasmon; A second metal layer is disposed on a second surface of the dielectric substrate, wherein the second surface is disposed opposite to the first surface; and A metal through hole connected to the first metal layer and the second metal layer; In which, a symmetrically arranged input structure and output structure and a symmetrically arranged first transition structure and second transition structure are also arranged on the first surface of the dielectric substrate, wherein the first transition structure is connected between the input structure and the circular quarter-mode waveguide pattern to enable a smooth transition between the input structure and the circular quarter-mode waveguide pattern, and the second transition structure is connected between the output structure and the circular quarter-mode waveguide pattern to enable a smooth transition between the input structure and the circular quarter-mode waveguide pattern, and the first transition structure and the second transition structure are adapted to the artificial surface plasmon.

2. The bandpass filter according to claim 1, characterized in that The circular quarter mode waveguide pattern comprises: a first portion, wherein the metal via is disposed at a circular edge of the first portion; The second part is connected to the first part, and the second part is provided with a plurality of slots along the symmetric direction of the input structure and the output structure or the first transition structure and the second transition structure to form the artificial surface plasmon.

3. The bandpass filter according to claim 2, characterized in that The second portion is provided with a plurality of first rectangular slots along the symmetry direction, and the plurality of first rectangular slots are arranged at equal intervals along a direction perpendicular to the symmetry direction to form the artificial surface plasmons.

4. The bandpass filter according to claim 3, characterized in that: The lengths of the plurality of first rectangular slots along the symmetry direction are the same, and the widths of the plurality of first rectangular slots along a direction perpendicular to the symmetry direction are the same.

5. The bandpass filter according to claim 2, characterized in that: The circular quarter mode waveguide pattern is symmetrically arranged along the symmetry direction, wherein the first portion and the second portion are both symmetrically arranged along the symmetry direction.

6. The bandpass filter according to any one of claims 2 to 5, characterized in that: The first transition structure is connected to the first part and the second part, and the second transition structure is connected to the first part and the second part, wherein the first transition structure and the second transition structure are both trapezoidal transition structures, so that the first transition structure is respectively adapted to the circular quarter-mode waveguide pattern along the symmetry direction and a direction perpendicular to the symmetry direction, and the second transition structure is respectively adapted to the circular quarter-mode waveguide pattern along the symmetry direction and a direction perpendicular to the symmetry direction.

7. The bandpass filter according to claim 6, characterized in that The first transition structure is provided with a plurality of second rectangular slots along the symmetric direction, and the plurality of second rectangular slots are arranged at equal intervals along a direction perpendicular to the symmetric direction, so that the first transition structure is adapted to the second portion of the circular quarter mode waveguide pattern along a direction perpendicular to the symmetric direction; The second transition structure is provided with a plurality of second rectangular slots along the symmetry direction, and the plurality of second rectangular slots are arranged at equal intervals along a direction perpendicular to the symmetry direction, so that the second transition structure is adapted to the second portion of the circular quarter mode waveguide pattern along a direction perpendicular to the symmetry direction; The second rectangular slot of the first transition structure and the second rectangular slot of the second transition structure are symmetrically arranged along the symmetry direction.

8. The bandpass filter according to claim 7, characterized in that: The lengths of the plurality of second rectangular slots of the first transition structure along the symmetry direction increase sequentially from the input structure or the output structure to the second portion, and the widths of the plurality of second rectangular slots along the direction perpendicular to the symmetry direction are the same, so that the first transition structure is adapted to the second portion along the symmetry direction; The lengths of the plurality of second rectangular slots of the second transition structure along the symmetry direction increase successively from the input structure or the output structure to the second part, and the widths along the direction perpendicular to the symmetry direction are the same, so that the second transition structure is adapted to the second part along the symmetry direction.

9. The bandpass filter according to any one of claims 1 to 5, characterized in that: The input structure comprises an input feeder and an input loading structure, wherein the input feeder is arranged vertically to the input loading structure; The output structure comprises an output feeder and an output loading structure, wherein the output feeder is arranged vertically to the output loading structure; The input feeder and the output feeder are symmetrically arranged, and the input loading structure and the output loading structure are symmetrically arranged.

10. The bandpass filter according to claim 9, characterized in that: The input loading structure and the output loading structure are both step impedance microstrip lines, including a first microstrip line and a second microstrip line, the first microstrip line is vertically arranged with the input feeder line or the output feeder line, the second microstrip line is connected with the first microstrip line and is horizontally arranged, and the characteristic impedance of the first microstrip line is greater than the characteristic impedance of the second microstrip line.

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