阅读说明：本技术 一种叉指结构加载的基片集成波导滤波器 (Substrate integrated waveguide filter loaded by interdigital structure ) 是由 董元旦 朱谊龙 杨涛 于 2020-08-21 设计创作，主要内容包括：本发明涉及波导技术领域,是一种叉指结构加载的基片集成波导滤波器,包括输入端口、输出端口、叉指结构和基片集成波导谐振腔结构；所述基片集成波导谐振腔结构设置在所述输入端口和输出端口之间；所述基片集成波导谐振腔结构包括顶层金属、底层金属和介质板层,所述介质板层上设置有阵列的金属化过孔,所述金属化过孔连通所述顶层金属和底层金属,以形成基片集成波导谐振腔；设置有至少两个所述基片集成波导谐振腔结构：相邻所述谐振腔之间设置有感性耦合窗；所述叉指结构设置在所述输入端口、输出端口和感性耦合窗中的一个或多个位置,减小滤波器尺寸,并且提高滤波器的选择性。(The invention relates to the technical field of waveguides, in particular to a substrate integrated waveguide filter loaded with an interdigital structure, which comprises an input port, an output port, the interdigital structure and a substrate integrated waveguide resonant cavity structure; the substrate integrated waveguide resonant cavity structure is arranged between the input port and the output port; the substrate integrated waveguide resonant cavity structure comprises a top layer metal, a bottom layer metal and a dielectric slab layer, wherein the dielectric slab layer is provided with an array of metallized through holes, and the metallized through holes are communicated with the top layer metal and the bottom layer metal to form a substrate integrated waveguide resonant cavity; at least two substrate integrated waveguide resonant cavity structures are arranged: an inductive coupling window is arranged between the adjacent resonant cavities; the interdigital structures are disposed at one or more locations within the input port, output port, and inductive coupling window, reducing filter size and increasing filter selectivity.)

1. A substrate integrated waveguide filter loaded with an interdigital structure is characterized by comprising an input port, an output port, the interdigital structure and a substrate integrated waveguide resonant cavity structure;

the substrate integrated waveguide resonant cavity structure is arranged between the input port and the output port;

the substrate integrated waveguide resonant cavity structure comprises a top layer metal, a bottom layer metal and a dielectric slab layer, wherein the dielectric slab layer is provided with an array of metallized through holes, and the metallized through holes are communicated with the top layer metal and the bottom layer metal to form a substrate integrated waveguide resonant cavity;

at least two substrate integrated waveguide resonant cavity structures are arranged:

an inductive coupling window is arranged between the adjacent substrate integrated waveguide resonant cavities;

the interdigital structures are disposed at one or more locations within the input port, output port, and inductive coupling window.

2. The filter of claim 1, wherein the resonance frequency of the interdigital structure coincides with the resonance frequency of the substrate-integrated waveguide resonator.

3. The filter of claim 2, wherein the interdigital structure is disposed at the inductive coupling window to form a third order filter.

4. The filter of claim 3, wherein the interdigital structure-loaded substrate integrated waveguide filter is provided with symmetrically reserved inductive coupling windows at two sides.

5. The substrate-integrated waveguide filter with the loaded interdigital structure according to claim 4, wherein the reserved inductive coupling window is internally provided with metal via holes arranged transversely.

6. The filter of claim 1, wherein the interdigital structures are disposed on the input port and the output port to form a fourth order filter.

7. The filter of claim 1, wherein the interdigital structure comprises three pairs of interdigital fingers.

Technical Field

The invention relates to the technical field of waveguides, in particular to a substrate integrated waveguide filter with an interdigital structure loaded.

Background

Substrate Integrated Waveguide (SIW) has the characteristics of a general cavity Waveguide, such as high power capacity and low insertion loss, and at the same time, it has the advantage of easy integration of a general planar circuit, and has received extensive attention from both academic and industrial fields. Filters based on the substrate integrated waveguide technology have been extensively studied and applied over the past decades, and various different types, filter responses, multi-pass bands, and reconfigurable substrate integrated waveguide filters have been widely studied. Despite its significant advantages, the substrate integrated waveguide filter has a significant disadvantage, namely its large size. Compared with the conventional microstrip filter or lumped parameter filter, the substrate integrated waveguide filter is much larger in lateral area. With the continuous development of modern wireless communication technology, miniaturization is a trend of communication systems, and therefore miniaturization of filters is also important.

At present, the miniaturization method of the substrate integrated waveguide filter mainly comprises a multilayer folding technology, a 1/n die cutting technology and a loading technology. The miniaturization method of the substrate integrated waveguide filter based on the multilayer folding technology is to vertically stack a plurality of resonant cavities, reduce the transverse area of the filter, and greatly reduce the volume of the filter under the condition of only slightly increasing the section height of the filter, but the method has the defects of complex processing and high price. The 1/n-mode die cutting technology is that the substrate integrated waveguide resonant cavity is cut into n parts along the center of the substrate integrated waveguide resonant cavity in a rotational symmetry mode, each 1/n-mode resonant cavity keeps the resonance characteristic of the original full-mode cavity, but because the cut cavity is not a totally-enclosed structure, certain electromagnetic energy leakage exists, and the quality factor of the cavity is reduced; the miniaturization method of the substrate integrated waveguide filter based on the loading technology is to increase the capacitance or the inductance of the resonant cavity by loading the metal or metamaterial structure, so that the frequency of the resonant cavity of the cavity is reduced, and the miniaturization is realized.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a substrate integrated waveguide filter loaded with an interdigital structure, which comprises an input port, an output port, the interdigital structure and a substrate integrated waveguide resonant cavity structure;

the substrate integrated waveguide resonant cavity structure is arranged between the input port and the output port;

the substrate integrated waveguide resonant cavity structure comprises a top layer metal, a bottom layer metal and a dielectric slab layer, wherein the dielectric slab layer is provided with an array of metallized through holes, and the metallized through holes are communicated with the top layer metal and the bottom layer metal to form a substrate integrated waveguide resonant cavity;

at least two substrate integrated waveguide resonant cavity structures are arranged:

an inductive coupling window is arranged between the adjacent substrate integrated waveguide resonant cavities;

the interdigital structures are disposed at one or more locations within the input port, output port, and inductive coupling window.

Further, the resonant frequency of the interdigital structure is consistent with the resonant frequency of the substrate integrated waveguide resonant cavity.

Further, the interdigital structure is disposed at the inductive coupling window to form a third order filter.

Furthermore, two sides of the interdigital structure are provided with symmetrical reserved inductive coupling windows.

Furthermore, metal through holes which are transversely arranged are arranged in the reserved inductive coupling window.

Further, the interdigital structures are arranged on the input port and the output port to form a fourth-order filter.

Further, the interdigital structure is composed of three pairs of interdigital fingers.

The invention has the beneficial effects that: the interdigital structure is used as a resonator and is designed to be mixed with the substrate integrated waveguide resonant cavity, and under the same frequency, the interdigital resonant structure has a smaller physical size than the substrate integrated waveguide resonant cavity, so that the filter has a compact structure; the interdigital capacitor of the interdigital structure is equivalent to that electric coupling is added on a transmission path, cross coupling between substrate integrated waveguide resonant cavities is introduced, a transmission zero point is generated on one side of a passband, and the selectivity of the filter is improved.

Drawings

The invention is further illustrated by the attached drawings, the examples of which are not to be construed as limiting the invention in any way.

FIG. 1 is a schematic diagram of a planar structure of a third-order filter according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of simulated S-parameters of a third order filter according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a planar structure of a fourth-order filter according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating simulated S parameters of a fourth order filter according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a layered structure of a resonant structure in an embodiment of the present invention.

1-an interdigitated structure; 2-substrate integrated waveguide resonant cavity; 3-metallizing the via hole; 4-reserving an inductive coupling window; 10-top metal; 20-a dielectric slab layer; 30-bottom layer metal.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples, which are preferred embodiments of the present invention.

As shown in fig. 1-5

The substrate integrated waveguide filter with the interdigital structure 1 loaded comprises an input port, an output port, the interdigital structure 1 and a substrate integrated waveguide resonant cavity 2 structure;

the substrate integrated waveguide resonant cavity 2 is structurally arranged between the input port and the output port;

the substrate integrated waveguide resonant cavity 2 structurally comprises a top layer metal 10, a bottom layer metal 30 and a dielectric slab layer 20, wherein the dielectric slab layer 20 is provided with an array of metallized through holes 3, and the metallized through holes 3 are communicated with the top layer metal 10 and the bottom layer metal 30 to form a substrate integrated waveguide resonant cavity 2;

at least two structures of the substrate integrated waveguide resonant cavity 2 are arranged:

an inductive coupling window is arranged between the adjacent substrate integrated waveguide resonant cavities 2;

the interdigital structure 1 is disposed at one or more of the input port, the output port, and the inductive coupling window.

The interdigital structure 1 can be equivalently regarded as a composite left-hand and right-hand transmission line structure, a resonator based on the composite left-hand and right-hand transmission line structure has unique characteristics different from a traditional right-hand transmission line structure resonator due to unique phase characteristics, has smaller physical size than the traditional right-hand transmission line structure resonator, and has smaller size compared with a substrate integrated waveguide transmission line, the interdigital capacitor of the composite left-hand and right-hand transmission line resonator realized by the interdigital structure 1 can be used for representing left-hand capacitance, and via holes with two grounded ends can be used for representing left-hand inductance;

preferably, the resonance frequency of the interdigital structure 1 is consistent with the resonance frequency of the substrate integrated waveguide resonant cavity 2, so that the electromagnetic signals generate resonance among different resonant cavities and then propagate.

Preferably, the interdigital structure 1 is disposed at the inductive coupling window to form a third order filter.

One implementation of this scheme: a standard PCB processing technology is adopted, a circuit substrate adopts a Rogers5880 substrate, the thickness is 0.508mm, the dielectric constant is 2.2, the loss tangent is 0.0009, the upper surface and the lower surface of the substrate are 0.018mm of metal copper, an input/output port is a coplanar waveguide structure with the characteristic impedance of 50 ohms, the coplanar waveguide structure is respectively connected with two substrate integrated waveguide resonant cavities 2, an interdigital structure 1 resonator is cascaded between the two substrate integrated waveguide resonant cavities 2, the substrate integrated waveguide resonant cavities 2 are surrounded by metallized through holes 3 to form a rectangular resonant cavity, the metallized through holes 3 are connected with the upper surface and the lower surface of metal, the diameter of the metal is 0.6mm, the distance between the through holes is smaller than 1mm, the interdigital structure 1 is cascaded at the center of a filter, the metallized through holes 3 with the diameter of 0.4mm are arranged on two sides, the total six through holes are arranged, two symmetrical reserved inductive coupling windows 4 are arranged between the two substrate, cross coupling between two substrate integrated waveguide resonant cavities 2 is provided, the working mode of the substrate integrated waveguide resonant cavities 2 is a TE101 mode, and an interdigital structure 1 works on the resonance frequency of a main mode and is consistent with the working frequency of the substrate integrated waveguide resonant cavities 2, so that three resonators form a triple-pole band-pass response;

the main path coupling is from the substrate integrated waveguide resonant cavity 2 to the interdigital structure 1, and then from the interdigital structure 1 to the other substrate integrated waveguide resonant cavity 2, two inductive coupling windows are reserved between the two substrate integrated waveguide resonant cavities 2, so that the two resonant cavities generate magnetic coupling, and a transmission zero point is generated on the left side of a pass band due to the cross coupling effect between the non-adjacent resonant cavities;

the designed center frequency is 10GHz and the 3dB bandwidth is 1.19GHz, and the structural parameters are shown in the following table, where the parameters are the dimensions, units (mm), noted in fig. 1:

l1	w1	wm	ls	ws	p1
						14.6	13.65	1.57	2.4	1.9	<1
d1	m1	n1	g1	r1
						0.6	2.88	0.2	0.2	0.4

as can be seen from the simulated S parameters of the third-order filter, a transmission zero is generated on the left side of the filter passband due to the cross coupling between the two substrate integrated waveguide resonant cavities 2, the filter has wider stopband rejection performance, and the out-of-band rejection exceeds 20dB within the range of 20 GHz.

Preferably, the interdigital structure 1 is disposed at the input port and the output port to form a fourth order filter.

The standard PCB processing technology is adopted, the circuit substrate is a Rogers5880 substrate, the thickness is 0.508mm, the dielectric constant is 2.2, the loss tangent is 0.0009, the upper surface and the lower surface of the substrate are 0.018mm of metal copper, the input and output ports of the filter are of a 50-ohm microstrip feed line structure, the two interdigital resonators are respectively located at the input and output ports, one end of each interdigital resonator is directly connected with 50-ohm microstrip feed, and the other end of each interdigital resonator is connected with the substrate integrated waveguide resonant cavity 2. The interdigital structure 1 resonator is composed of three pairs of interdigital parts, the periphery of the substrate integrated waveguide resonant cavity 2 is surrounded by the metallized through holes 3 to form a rectangular resonant cavity, a closed structure is formed, the diameter of the through holes is 0.6mm, and the distance between the through holes is smaller than 1 mm. An inductive coupling window is reserved between the two substrate integrated waveguide resonant cavities 2, the width of the window can control the coupling coefficient between the two resonant cavities, the two substrate integrated waveguide resonant cavities 2 work in a TE101 mode, the two interdigital resonators work in a main resonance mode of the interdigital resonators, the resonance frequency of the interdigital resonators is the same as the frequency of the substrate integrated waveguide resonant cavities 2, and when proper coupling coefficients are formed among the four resonators, four-pole passband response can be formed;

the designed center frequency is 10GHz and the 3dB bandwidth is 1.19GHz, and the structural parameters are shown in the following table, where the parameters are the dimensions, units (mm), noted in fig. 3:

l2	w2	wm	vx	vy	p1
						14.45	13.5	1.57	0.8	1.7	<1
d1	ws	g2	m2	n2	dy
						0.6	6.35	0.2	2.77	0.2	1.5

as can be seen from the simulation S parameter of the fourth-order filter, a transmission zero is generated on the left side and the right side of the passband, the out-of-band rejection effect is excellent, and the selectivity is good.

It can be understood that the interdigital structure 1 is cascaded at two adjacent substrate integrated waveguide resonant cavities 2 as a resonant cavity or is arranged at an input/output port, for a substrate integrated waveguide filter, a plurality of resonant cavities can be integrated, and the performance of the filter can be improved and the size of the filter can be reduced as much as possible by combining the interdigital structure 1 resonant cavities.

In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "center", "top", "bottom", "top", "root", "inner", "outer", "peripheral", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, only for the purpose of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Where "inside" refers to an interior or enclosed area or space. "periphery" refers to an area around a particular component or a particular area.

In the description of the embodiments of the present invention, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", "third", "fourth" may explicitly or implicitly include one or more of the features. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "assembled" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description of the embodiments of the invention, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

In the description of the embodiments of the present invention, it is to be understood that "-" and "-" denote ranges of two numerical values, and the ranges include endpoints. For example, "A-B" means a range greater than or equal to A and less than or equal to B. "A to B" represents a range of A or more and B or less.

In the description of the embodiments of the present invention, the term "and/or" herein is only one kind of association relationship describing an associated object, and means that there may be three kinds of relationships, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.