CN111600103A - A filter based on printed ridge-gap waveguide - Google Patents

Abstract

An embodiment of the present invention provides a filter based on a printed ridge gap waveguide, which is characterized by comprising: a ground layer 113, a dielectric substrate 114, an air layer plate 115 and a metal parallel plate 116; wherein: the dielectric substrate 114 includes a filter The microstrip line structure 117 and the mushroom bed array 118, the mushroom bed array 118 includes a plurality of metal units 121, the dielectric substrate 114 is located between the ground layer 113 and the air layer plate 115; the ground layer 113 includes an input port 111 and an output port 112. The port 111 is connected to the metal parallel plate 116 through the feeding conductor passing through the dielectric substrate 114, and the output port 112 is connected to the metal parallel plate 116 through the feeding conductor passing through the dielectric substrate 114; the air layer plate 115 is a through hole with a preset shape The air layer plate 115 is located between the metal parallel plate 116 and the dielectric substrate 114 .

Description

A filter based on printed ridge-gap waveguide

technical field

The present invention relates to the technical field of millimeter wave radio frequency, in particular to a filter based on a printed ridge gap waveguide.

Background technique

Millimeter-wave wireless communication technology is an extension of microwave wireless communication technology to higher frequency bands. The main reasons why millimeter-wave wireless communication technology has received widespread attention and attention in recent years include: the corresponding spectrum resources of millimeter-wave and the good transmission characteristics of millimeter-wave itself. Millimeter wave communication technology has become the development need of many emerging technologies. For example, at the 2019 World Wireless Telecommunications Conference, a new topic of 1.13 was established for the 5th generation mobile networks (5G) system, and the available frequency band was found above 6GHz, and the frequency range of the study was 24.25-86GHz. Facing the new requirements of the 5th generation mobile networks (5G) system, it is urgent to research and design matching millimeter wave devices.

As an important part of a radio frequency (RF) wireless communication system, a filter has the function of dividing and extracting signal frequencies, and its performance directly determines the communication quality of the entire communication system. The traditional microstrip filter directly connects the microstrip line structure on the dielectric substrate through the input port, and then connects the output port through the microstrip line structure, so that the current is transmitted in the microstrip line to realize the filtering function. However, when high-frequency electromagnetic waves are filtered, the current in the microstrip line structure is high, that is, the current in the dielectric substrate is high, and when the current in the dielectric substrate is high, a high transmission loss will occur, making the traditional The insertion loss of the microstrip filter is high.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a filter based on a printed ridge gap waveguide, so as to reduce the insertion loss of the filter. The specific technical solutions are as follows:

A filter based on a printed ridge gap waveguide, comprising: a ground layer 113, a dielectric substrate 114, an air layer plate 115 and a metal parallel plate 116; wherein:

The dielectric substrate includes a filter microstrip line structure 117 and a mushroom bed array 118. The mushroom bed array 118 includes a plurality of metal units 121, and each metal unit 121 includes a metal patch and a metal patch located under the metal patch. The metal through holes 130 connected to the chips, the metal through holes 130 included in the metal unit 121 are connected to the ground layer 113, and the dielectric substrate 114 is located between the ground layer 113 and the air layer plate 115;

The ground layer 113 includes an input port 111 and an output port 112, the input port 111 is connected to the metal parallel plate 116 through a feed conductor passing through the dielectric substrate 114, and the output port 112 passes through the dielectric substrate The feed conductor of 114 is connected to the metal parallel plate 116;

The air layer plate 115 is a substrate with a preset shape through hole, and the air layer plate 115 is located between the metal parallel plate 116 and the dielectric substrate 114 ;

The medium between the mushroom bed array 118 and the metal parallel plate 116 is air, and the distance between the mushroom bed array 118 and the metal parallel plate 116 is less than a quarter wavelength of the electromagnetic wave to be filtered.

Optionally, the mushroom bed array 118 is located around the filter microstrip line structure 117 , and the distance between every two adjacent metal units 121 included in the mushroom bed array 118 is the same.

Optionally, the filter microstrip line structure 117 includes: a coaxial to ridge line transition line, an open-circuit coupling line and a stepped impedance open-circuit branch, and the coaxial to ridge line transition line is connected to the open-circuit coupling line, so The open-circuit coupling line is connected to the stepped impedance open-circuit branch.

Optionally, the coaxial to ridge line transition line includes a first microstrip feed line 124 and a second microstrip feed line 125, the open-circuit coupling line includes a first open-circuit coupling line 1261 and a second open-circuit coupling line 1262, The first microstrip feed line 124 is connected to the first open-circuit coupling line 1261 , and the second microstrip feed line 125 is connected to the second open-circuit coupling line 1262 .

Optionally, the first microstrip feed line 124 and the second microstrip feed line 125 include metal through holes 131 connected to the ground layer 113 .

Optionally, the distance between two adjacent metal through holes 131 included in the first microstrip feed line 124 is the same as the distance between two adjacent metal units 121 included in the mushroom bed array 118 , The distance between two adjacent metal through holes 131 included in the second microstrip feed line 125 is the same as the distance between two adjacent metal units 121 included in the mushroom bed array 115 .

Optionally, the stepped impedance open-circuit branch includes a first sub-branch 127, a second sub-branch 128 and a third sub-branch 129, the first sub-branch 127 is connected to the first open-circuit coupling line 1261 and the second sub-branch 1261. Open coupled lines 1262 are connected.

Optionally, the first sub-branch 127 and the second sub-branch 128 have different impedances, and the second sub-branch 128 and the third sub-branch 129 have the same impedance.

Optionally, the line where the second sub-branch 128 and the third sub-branch 129 are located is parallel to the line where the open-circuit coupling line is located.

Optionally, the first sub-branch 127 includes a metal through hole 131 connected to the ground layer 113 .

The embodiment of the present invention has at least the following beneficial effects: since the medium between the mushroom bed array and the parallel metal plate is air, and the distance between the mushroom bed array and the parallel metal plate is less than a quarter wavelength of the electromagnetic wave to be filtered, the mushroom bed array and the parallel metal plate are made of air. The bed array and the parallel metal plates form an electromagnetic bandgap structure, so the transmission of electromagnetic waves between the mushroom bed array and the parallel metal plates is hindered. The input port is connected to the parallel metal plate, and the filter microstrip line structure is not connected to the input port, so that the electromagnetic waves radiated by the parallel metal plate can be transmitted in the air between the filter microstrip line structure and the parallel metal plate. Since electromagnetic waves are transmitted in the air without being transmitted in a dielectric substrate, the embodiment of the present invention reduces the transmission loss during filtering and reduces the insertion loss of the filter.

Of course, it is not necessary for any product or method of the present invention to achieve all of the advantages described above at the same time.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic structural diagram of a filter according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a dielectric substrate according to an embodiment of the present invention;

3 is a schematic structural diagram of a coaxial to ridge line transition line provided by an embodiment of the present invention;

4 is a schematic structural diagram of a metal unit according to an embodiment of the present invention;

5 is an equivalent circuit diagram of a filter provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of an S-parameter simulation result of a filter provided by an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to provide a filter with low insertion loss, as shown in FIG. 1 , an embodiment of the present invention provides a filter based on a printed ridge gap waveguide, the filter includes: a ground layer 113 , a dielectric substrate 114 , an air Laminates 115 and metal parallel plates 116; where:

The dielectric substrate 114 includes a filter microstrip line structure 117 and a mushroom bed array 118. As shown in FIG. 2, the mushroom bed array 118 includes a plurality of metal units 121, and each metal unit 121 includes a metal patch and is located under the metal patch The metal through hole 130 connected to the metal patch, the metal through hole 130 included in the metal unit 121 is connected to the ground layer 113, and the dielectric substrate 114 is located between the ground layer 113 and the air layer plate 115;

The ground layer 113 includes an input port 111 and an output port 112. The input port 111 is connected to the metal parallel plate 116 through a feed conductor passing through the dielectric substrate 114, and the output port 112 is connected to the metal parallel plate 116 through a feed conductor passing through the dielectric substrate 114. connected;

The air layer plate 115 is a substrate with a preset shape through hole, and the air layer plate 115 is located between the metal parallel plate 116 and the dielectric substrate 114;

The medium between the mushroom bed array 118 and the metal parallel plate 116 is air, and the distance between the mushroom bed array 118 and the metal parallel plate 116 is less than a quarter wavelength of the electromagnetic wave to be filtered.

It should be noted that the mushroom bed array 118 in FIG. 1 includes a plurality of metal units 121 with the same shape. In FIG. 1 , the metal vias 130 included in the metal units 121 are not shown to be connected to the gold ground layer 113 . In fact, the metal vias 130 included in each metal unit 121 are connected to the ground layer 113 . In addition, on the ground layer 113, the white dot on the left side represents the input port 111, and the white point on the right side represents the output port 112. In FIG. 1, the input port 111 is not shown connected to the metal parallel plate 116 through the feeding conductor, and the output port 112 The input port 111 is connected to the metal parallel plate 116 through the feed conductor, and the output port 112 is actually connected to the metal parallel plate 116 through the feed conductor.

The embodiment of the present invention has at least the following beneficial effects: since the medium between the mushroom bed array and the parallel metal plate is air, and the distance between the mushroom bed array and the parallel metal plate is less than a quarter wavelength of the electromagnetic wave to be filtered, the mushroom bed array and the parallel metal plate are made of air. The bed array and the parallel metal plates form an electromagnetic bandgap structure, so the transmission of electromagnetic waves between the mushroom bed array and the parallel metal plates is hindered. The input port is connected to the parallel metal plate, and the filter microstrip line structure is not connected to the input port, so that the electromagnetic waves radiated by the parallel metal plate can be transmitted in the air between the filter microstrip line structure and the parallel metal plate. Since electromagnetic waves are transmitted in the air without being transmitted in a dielectric substrate, the embodiment of the present invention reduces the transmission loss during filtering and reduces the insertion loss of the filter.

In the embodiment of the present invention, the electromagnetic wave to be filtered is an electromagnetic wave that is filtered by using the filter provided in the embodiment of the present invention, and the wavelength (λ) of the electromagnetic wave to be filtered is the wave speed (c)/operating frequency (f), where the wave speed c is the speed of light, and the operating frequency f can be set according to actual needs, for example, the operating frequency f is 35GHZ.

In the embodiment of the present invention, the ground layer 113 , the metal parallel plate 116 , the filter microstrip line structure 117 and the metal unit 121 are all conductive metals. Alternatively, the conductive metal may be brass.

Optionally, as shown in FIG. 1 , the air layer board 115 may be a printed circuit board (Printed Circuit Board, PCB) having through holes in a preset shape, so that the hollowed out middle part of the air layer board 115 includes an air gap. For example, the preset shape may be a rectangle with an area no smaller than the area occupied by the array of mushroom beds 118 .

1 , in the embodiment of the present invention, the metal parallel plates 116 and the periodic mushroom bed array 118 form an electromagnetic band gap structure, since electromagnetic waves can propagate in the air, and the electromagnetic band gap structure prevents the electromagnetic waves from traveling in the mushroom bed array 118 and the metal parallel plate 116 , so that the electromagnetic wave propagates in the air gap between the filter microstrip line structure 117 and the metal parallel plate 116 . The periodicity of the mushroom bed array 118 is embodied in that the distance between every two adjacent metal units 121 included in the mushroom bed array 118 is the same.

In one embodiment, referring to FIG. 1 , the ground layer 113 includes an input port 111 and an output port 112 . In this embodiment of the present invention, a coaxial feeding technology is used, so the input port 111 and the output port 112 are SMA connectors. Among them, the SMA connector is a coaxial connector, and the connector of the connector is 2.4 millimeters (mm). The SMA connector includes an outer conductor and an inner conductor, the outer conductor is connected to the ground layer 113 , the inner conductor is the feed conductor described above, and an insulating layer exists between the outer conductor and the inner conductor. Alternatively, the feed conductors may be electrical wires, such as copper wires.

Optionally, the model of the dielectric substrate 114 may be Roger RT6002, the dielectric constant is 2.94, the thickness is 0.762 mm, and the dielectric loss is 0.0012.

In the embodiment of the present invention, the filter microstrip line structure 117 can be printed on the dielectric substrate 114 by means of a printed circuit board, so that the dielectric substrate 114 of the embodiment of the present invention has a light structure, low cost, and better loss performance than traditional ones. Microstrip waveguides and other advantages have broad application prospects.

In one embodiment, the filter microstrip line structure 117 includes: a coaxial to ridge line transition line, an open-circuit coupling line, and a stepped impedance open-circuit branch, wherein the coaxial-to-ridge line transition line is connected to the open-circuit coupling line, and the open-circuit coupling The line is connected to the stepped impedance open stub.

Specifically, referring to FIG. 2, the coaxial to ridge line transition line includes a first microstrip feed line 124 and a second microstrip feed line 125, and the open-circuit coupling line includes a first open-circuit coupling line 1261 and a second open-circuit coupling line 1262. A microstrip feed line 124 is connected to the first open-circuit coupling line 1261 , and a second microstrip feed line 125 is connected to the second open-circuit coupling line 1262 .

In the embodiment of the present invention, a feed conductor (not shown in FIG. 1 ) is connected between the input port 111 included in the ground layer 113 in FIG. 1 and the metal parallel plate 116 , and the output port 112 included in the ground layer 113 A feed conductor (not shown in FIG. 1 ) is also connected between the metal parallel plate 116 . The feeding conductor passes through the dielectric substrate 114 and the air layer plate 115 , that is, the feeding conductor is not connected to the dielectric substrate 114 .

In the embodiment of the present invention, coaxial to ridgeline transition feed lines, namely the first microstrip feed line 124 and the second microstrip feed line 125, are designed at the feed of the dielectric substrate 114, which can achieve good impedance matching at the input end.

Referring to FIG. 3 , FIG. 3 is a structural diagram of the first microstrip feed line 124 . In FIG. 3 , the first microstrip feed line 124 includes a circular through hole with R _in as the radius, and the feed conductor can pass through the circular through hole with R _in to connect the input port 111 and the metal parallel plate 116 .

The structure of the second microstrip feeder 125 is similar to that of the first microstrip feeder 124. The second microstrip feeder 125 includes a circular through hole through which a feed conductor can pass through to connect the output port 112 and metal parallel plates 116.

The size of the transition line from the coaxial to the ridge line can be set according to actual needs, which is not specifically limited in the embodiment of the present invention. For example, _Wline = _1.38mm , _Lline = _4.3mm , _Wm =1.8mm, _Lm =2.2mm, Rout=0.85mm, Rin=0.59mm.

In one embodiment, referring to FIG. 2 , the first microstrip feed line 124 and the second microstrip feed line 125 include metal vias 131 connected to the ground layer 113 . For example, the first microstrip feed line 124 in FIG. 2 includes two metal through holes 131 , and the second microstrip feed line 125 includes two metal through holes 131 .

It should be noted that, for the convenience of reading, each metal through hole 131 is not shown connected to the ground layer 113 in FIG. 1 , but actually the metal through hole 131 is connected to the ground layer 113 .

In a possible embodiment, referring to FIG. 4 , a basic constituent unit of the printed ridge gap waveguide is a quasi-periodic mushroom-shaped bandgap unit, that is, a metal unit 121 . The metal unit 121 together with the metal parallel plate 116 forms an electromagnetic bandgap structure. By introducing the filter microstrip line structure 117 in the center of the electromagnetic bandgap structure, the propagation of the quasi-transverse electromagnetic wave (Transverse Electromagnetic Wave, TEM) mode is supported.

In the embodiment of the present invention, the mushroom bed array 118 is located around the filter microstrip line structure 117, and the distance between every two adjacent metal units 121 included in the mushroom bed array 117 is the same. For example, referring to FIG. 4 , the distance between every two adjacent metal units 121 included in the mushroom bed array is a=1.7 mm.

In a possible embodiment, the distance between two adjacent metal through holes 131 included in the first microstrip feed line 124 is the same as the distance between two adjacent metal units 121 included in the mushroom bed array 118 , the distance between the two adjacent metal through holes 131 included in the second microstrip feed line 125 is the same as the distance between the two adjacent metal units 121 included in the mushroom bed array 118 , which can more efficiently suppress the electromagnetic waves in The propagation between the mushroom bed array 118 and the parallel metal plates 116 can also prevent electromagnetic waves from propagating in the substrate below the filter microstrip line structure 117 , that is, preventing electromagnetic waves from propagating between the dielectric substrate 114 and the ground layer 113 .

It should be noted that the distance between the adjacent metal through holes 131 included in the microstrip feed line refers to the distance between the center points of the adjacent metal through holes 131; the distance between the adjacent metal units 121 , which refers to the distance between the center points of adjacent metal units 121 .

Referring to FIG. 4 , the diameter d _via of the metal through hole 130 is 0.39 mm, the diameter d _cap of the circular metal patch is 1.5 mm, and the height h of the air layer is 0.289 mm. The size of the mushroom bed array is only an example provided by the embodiment of the present invention, and the size of the mushroom bed array can also be determined according to actual needs, which is not specifically limited in the embodiment of the present invention. The height of the air layer refers to the distance between the mushroom bed array 118 and the parallel metal plate 116 , and also the distance between the circular metal patch in the mushroom bed array and the parallel metal plate 116 .

The embodiments of the present invention can also bring the following beneficial effects: using a periodic mushroom bed array to form an artificial magnetic conductor, the mushroom bed array combined with the filter microstrip line structure can greatly improve the propagation loss and anti-interference ability of the microstrip line transmission. Compared with the microstrip line, it has smaller insertion loss, and has the characteristics of self-encapsulation, miniaturization and integration. It also overcomes the shortcomings of the large size and heavy weight of the metal waveguide structure, and has the advantages of small size, compact structure and easy processing. , Easy to integrate, low cost and wide range of applications.

In one embodiment, referring to FIG. 2 , the stepped impedance open branch includes a first sub-branch 127 , a second sub-branch 128 and a third sub-branch 129 , the first sub-branch 127 is coupled to the first open circuit 124 and the second open circuit Coupling lines 125 are connected.

In one embodiment, the impedances of the first sub-branch 127 and the second sub-branch 128 are different, and the impedances of the second sub-branch 128 and the third sub-branch 129 are the same.

In one embodiment, referring to FIG. 2 , the line where the second sub-branch 128 and the third sub-branch 129 are located is parallel to the line where the open-circuit coupling line is located. Since the distance between the adjacent metal units 121 included in the mushroom bed array 118 is the same, the line where the second sub-branch 128 and the third sub-branch 129 are arranged is parallel to the line where the open-circuit coupling line is arranged, so that the mushroom bed array 118 can be arranged more conveniently. the position of each metal unit 121 .

In the embodiment of the present invention, the size of the filter microstrip line structure 117 may be set according to actual requirements, which is not specifically limited in the embodiment of the present invention.

Exemplarily, in a possible embodiment, the line width of the transmission line of the first sub-branch 127 may be larger than that of the second sub-branch 128 and the third sub-branch 129 . For example, the line width of the transmission line of the first sub-branch is 2.4mm, the line length is 1.35mm, the line width of the transmission line of the second sub-branch is 0.3mm, the line length is 1.62mm, the line width of the transmission line of the third sub-branch is 0.3mm, The wire length is 1.62mm.

In one embodiment, the first sub-section 127 includes a metal via 131 connected to the ground layer 113 . For example, as shown in FIG. 2 , the first subsection 127 includes one metal through hole 131 .

Optionally, the first sub-branch 127 may include a plurality of metal through holes 131 . When the first sub-branch 127 includes a plurality of metal through holes 131 , the gaps between adjacent metal through holes 131 included in the first sub-branch 127 The distance is the same as the distance between two adjacent metal units 121 included in the mushroom bed array 118 .

The embodiment of the present invention also has the following beneficial effects: the stepped impedance open-circuit branch in the filter in the embodiment of the present invention includes three sub-branchs, forming an impedance ladder T-shaped structure circuit, which has additional advantages compared to the traditional T-shaped structure filter. Two transmission zeros, better shielding and suppressing out-of-band interference. The T-shaped structure circuit includes two parallel coupling lines and three impedance branches, which are combined with the electromagnetic bandgap structure formed by the periodic mushroom bed array. Since the filter of the embodiment of the present invention has two additional transmission zeros, the filter The operating frequency band selectivity of the filter is higher, and the filtering characteristics of the filter are better.

Although the traditional microstrip filter has the advantages of low production cost, small size and light weight, it also has high insertion loss, especially in the millimeter wave band, its performance is far inferior to that in the low frequency band. However, the metal waveguide structure is bulky, heavy, and expensive. Since millimeter-wave devices based on PCB technology have low cost and are easy to integrate with other devices and chips on the PCB, it is more necessary to study millimeter-wave devices based on PCB technology to better meet user needs.

Based on this, the periodic mushroom bed array 118 , the filter microstrip line structure 117 , the air layer plate 115 and the metal parallel plate 116 in the embodiment of the present invention form a ridge-gap waveguide structure. The ridge-gap waveguide structure in the embodiment of the present invention is realized based on the traditional PCB technology, and the design method is flexible and simple, and is extremely easy to process. 2, in the embodiment of the present invention, the periodic mushroom bed array 118 is located around the filter microstrip line structure 117 (for example, four rows of periodic metal units 121 are formed), surrounding the filter microstrip line structure 117, the periodic mushroom The bed array 118 and the metal parallel plate 116 form an electromagnetic band gap structure, so that the electromagnetic waves radiated by the parallel metal plate 116 can be transmitted in the air between the filter microstrip line structure 117 and the parallel metal plate 116 without contacting the dielectric substrate, so that the The filter circuit structure can realize the broadband electromagnetic shielding effect without direct physical contact. Therefore, when the filter is integrated with other devices or chips, compared with the traditional microstrip line filter, the embodiment of the present invention does not need to add additional shielding cases and isolation components, and does not need to consider the influence of resonance caused by adding additional components.

In addition, in the embodiments of the present invention, air is used as the propagation medium of electromagnetic waves, which saves the loss of dielectric materials to a large extent.

By using the ridge-gap waveguide embodiment provided by the embodiment of the present invention, the filter can be operated in the required millimeter wave frequency band. For example, the working frequency band of the filter provided by the embodiment of the present invention includes 31.6 GHz (Giga Hertz, GHz)-41.6 GHz, which is one of the widely used millimeter wave bands in the 5G technology, so that the embodiment of the present invention provides The filter is applied in 5G communication system.

The circuit structure of the filter in the high-selectivity and low-insertion-loss millimeter-wave filter based on the printed ridge-gap waveguide provided by the embodiment of the present invention is shown in FIG. 5 , where Port1 represents the input port, Port2 represents the output port, and Z represents the impedance , θ represents the impedance phase.

In the embodiment of the present invention, the impedance of the second sub-branch 128 and the impedance of the third sub-branch 129 are the same as Z ₂ ; the impedance of the first sub-branch 127 is Z ₁ ; the open-circuit coupling line impedances are Z _e1 and Z _o1 . The impedances of the first microstrip feed line 124 and the second microstrip feed line 125 are the same, and both are Z ₀ .

The impedance and impedance phase of the filter microstrip line structure 117 may be set according to actual needs, which are not specifically limited in this embodiment of the present invention. For example, Z _e1 =138Ω, Z _o1 =31Ω, Z ₁ =91Ω, Z ₂ =104Ω, Z ₀ =50Ω, θ=π/2.

In order to demonstrate the filtering effect of the filter provided by the embodiment of the present invention, refer to FIG. 6 , which is a schematic diagram of the simulation result of the S-parameter of the filter provided by the embodiment of the present invention, wherein the S-parameter includes return loss (S ₁₁ ) and Transmission coefficient (S ₂₁ ), in FIG. 6 , the line segment with squares represents S ₁₁ of the filter provided by the embodiment of the present invention, and the line segment with triangles represents S ₂₁ of the filter provided by the embodiment of the present invention. The abscissa in FIG. 6 represents the frequency, and the ordinate represents the value of the S parameter.

In the embodiment of the present invention, the passband bandwidth (S ₁₁ ≤-10dB) of the filter is 31.6GHz-40.6GHz, and the relative bandwidth is 24.9%. It can be seen from FIG. 6 that the filter provided by the embodiment of the present invention has two transmission zeros at 29.8 GHz and 41.5 GHz. Therefore, the filter provided by the embodiment of the present invention has better isolation to the millimeter-wave band outside the passband, and achieves stronger suppression of out-of-band interference. In addition, the bandpass filter provided by the embodiment of the present invention adopts the technology based on the printed ridge-gap waveguide, and has the advantages of low insertion loss, high selectivity and good impedance matching in the passband.

In the embodiment of the present invention, a bandpass filter with a stepped impedance T-shaped structure is designed in the printed ridge gap waveguide technology, and the position of the transmission zero point is adjusted by adjusting the impedance ratio of the stepped impedance branch, thereby realizing high selectivity of the filter operating frequency. The periodic mushroom bed array surrounds the filter microstrip line structure to form a new type of electromagnetic transmission structure, and the filter microstrip line structure can realize the broadband electromagnetic shielding effect without direct physical contact. In addition, the embodiments of the present invention use air as the propagation medium, which largely avoids the loss of dielectric materials. The millimeter wave filter of the invention has the advantages of self-encapsulation, light structure, low cost, better loss performance than traditional microstrip devices, and the like. In addition, compared with traditional waveguides, ridge-gap waveguides have the characteristics of lower cost, low loss, and easy heat dissipation, and are more suitable for scenarios with higher operating frequencies and higher power capacity density.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

Each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for other embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference may be made to some descriptions of the method embodiments for related parts.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A filter based on a printed ridge gap waveguide, characterized by comprising: a ground layer (113), a dielectric substrate (114), an air layer plate (115) and a metal parallel plate (116); wherein: The dielectric substrate (114) includes a filter microstrip line structure (117) and a mushroom bed array (118), the mushroom bed array (118) includes a plurality of metal units (121), and each metal unit (121) includes A metal patch and a metal through hole (130) located under the metal patch and connected to the metal patch, the metal through hole (130) included in the metal unit (121) is connected to the ground layer (113), and the A dielectric substrate (114) is located between the ground layer (113) and the air layer plate (115); The ground layer (113) includes an input port (111) and an output port (112), the input port (111) is connected to the metal parallel plate (116) through a feed conductor passing through the dielectric substrate (114) connected, the output port (112) is connected to the metal parallel plate (116) through a feed conductor passing through the dielectric substrate (114); The air layer plate (115) is a substrate with a preset shape through hole, and the air layer plate (115) is located between the metal parallel plate (116) and the dielectric substrate (114); The medium between the mushroom bed array (118) and the parallel metal plate (116) is air, and the distance between the mushroom bed array (118) and the parallel metal plate (116) is smaller than the electromagnetic wave to be filtered. quarter wavelength. 2. The filter according to claim 1, wherein the mushroom bed array (118) is located around the filter microstrip line structure (117), and the mushroom bed array (118) includes a phase The distance between every two adjacent metal units (121) is the same. 3. The filter according to claim 1, wherein the filter microstrip line structure (117) comprises: a coaxial to ridge line transition line, an open-circuit coupling line and a stepped impedance open-circuit branch, the coaxial line A transition line to the ridge line is connected to the open-circuit coupling line, and the open-circuit coupling line is connected to the stepped impedance open-circuit branch. 4. The filter of claim 3, wherein the coaxial to ridge transition line comprises a first microstrip feeder (124) and a second microstrip feeder (125), the open-circuit coupling The line includes a first open-circuit coupled line (1261) and a second open-circuit coupled line (1262), the first microstrip feed line (124) is connected to the first open-circuit coupled line (1261), the second microstrip feed line (1261) A feeder line (125) is connected to the second open-circuit coupling line (1262). 5. The filter according to claim 4, characterized in that, the first microstrip feed line (124) and the second microstrip feed line (125) comprise metal through holes ( 131). 6 . The filter according to claim 5 , wherein the distance between two adjacent metal through holes ( 131 ) included in the first microstrip feed line ( 124 ) is the same as the distance between the mushroom bed arrays. 7 . The distance between two adjacent metal units (121) included in (118) is the same, and the distance between two adjacent metal through holes (131) included in the second microstrip feed line (125) is the same as the distance between the two adjacent metal through holes (131) included in the second microstrip feed line (125). The distance between two adjacent metal units (121) included in the mushroom bed array (115) is the same. 7. The filter according to claim 4, wherein the stepped impedance open-circuit branch comprises a first sub-branch (127), a second sub-branch (128) and a third sub-branch (129), the A sub-branch (127) is connected to the first open coupling line (1261) and the second open coupling line (1262). 8. The filter according to claim 7, wherein the impedance of the first sub-branch (127) and the second sub-branch (128) are different, and the second sub-branch (128) and the The impedance of the third sub-branch (129) is the same. 9 . The filter according to claim 7 , wherein a straight line where the second sub-branch ( 128 ) and the third sub-branch ( 129 ) are located is parallel to a straight line where the open-circuit coupling line is located. 10 . 10. The filter according to claim 7, wherein the first sub-branch (127) comprises a metal through hole (131) connected to the ground layer (113).

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