CN117638437B - Waveguide bandpass filter and electrical equipment - Google Patents

Abstract

The invention provides a waveguide bandpass filter and an electrical device. The filter provided by the invention comprises an input waveguide cavity, a first resonant cavity, an output waveguide cavity and a second resonant cavity; a first common wall is arranged between the input waveguide cavity and the output waveguide cavity, and a second common wall is arranged between the first resonant cavity and the second resonant cavity; the input waveguide cavity is isolated from the first resonant cavity by a first metal diaphragm, and the output waveguide cavity is isolated from the second resonant cavity by a second metal diaphragm; a first gap is formed in the middle of the second public wall, and the length of the first gap is equal to one half of the free space wavelength corresponding to the center frequency of the filter; the first metal diaphragm is provided with a first coupling window which is communicated with the input waveguide cavity and the first resonant cavity, and the second metal diaphragm is provided with a second coupling window which is communicated with the output waveguide cavity and the second resonant cavity. The invention provides a waveguide band-pass filter and electrical equipment, wherein three-order band-pass filter response can be realized by two waveguide resonant cavities, and the size of the filter is reduced.

Description

Waveguide bandpass filter and electrical equipment

Technical Field

The present invention relates to the field of filters, and in particular to a waveguide bandpass filter and electrical equipment.

Background technique

A filter is a frequency-selective device that allows specific frequency components in a signal to pass through while greatly attenuating other frequency components. By utilizing this frequency-selective function of the filter, interference noise can be filtered out or spectrum analysis can be performed.

At present, with the rapid development of broadband communication and carrier aggregation technology, research in the field of broadband communication is becoming increasingly active. For waveguide bandpass filters, broadband design is mainly achieved by cascading multi-stage single-mode resonant cavities.

However, the existing cascade design requires N (N is a positive integer) waveguide resonant cavities to achieve an N-order bandpass filter response, and as the order of the cascade increases, the volume of the filter increases significantly.

Summary of the invention

In order to solve at least one of the problems mentioned in the background technology, the present invention provides a waveguide bandpass filter and an electrical device, which can achieve a third-order bandpass filter response by using only two waveguide resonant cavities, thereby reducing the size of the filter.

In order to achieve the above object, the present invention provides the following technical solutions:

In a first aspect, the present invention provides a waveguide bandpass filter, comprising a first waveguide cavity and a second waveguide cavity, wherein the first waveguide cavity comprises an input waveguide cavity and a first resonant cavity, and the second waveguide cavity comprises an output waveguide cavity and a second resonant cavity; a first common wall is provided between the input waveguide cavity and the output waveguide cavity, so that the input waveguide cavity and the output waveguide cavity are adjacent to each other along a first direction, and a second common wall is provided between the first resonant cavity and the second resonant cavity, so that the first resonant cavity and the second resonant cavity are adjacent to each other along the first direction;

In the second direction, the input waveguide cavity and the first resonant cavity are isolated by the first metal diaphragm, and the output waveguide cavity and the second resonant cavity are isolated by the second metal diaphragm;

A first slot extending along a third direction is formed in the middle of the second common wall, the first slot connects the first resonant cavity and the second resonant cavity, and the length of the first slot along the third direction is equal to half of the free space wavelength corresponding to the center frequency of the filter;

The first metal diaphragm has a first coupling window connecting the input waveguide cavity and the first resonant cavity, and the second metal diaphragm has a second coupling window connecting the output waveguide cavity and the second resonant cavity;

The cavity wall of the input waveguide cavity opposite to the first metal diaphragm serves as the input end of the filter, and the cavity wall of the output waveguide cavity opposite to the second metal diaphragm serves as the output end of the filter. The first direction, the second direction and the third direction are perpendicular to each other.

As an optional embodiment, a second slit connecting the first resonant cavity and the second resonant cavity is also opened on the second common wall, the second slit extends along the third direction, the second slit is spaced apart from the first slit along the second direction, and the length of the second slit along the third direction is less than the length of the first slit along the third direction.

As an optional implementation, the second gap is located between the first gap and the first metal diaphragm.

As an optional implementation manner, the first metal diaphragm and the second metal diaphragm are symmetrically arranged with respect to the first common wall.

As an optional implementation manner, the first coupling window and the second coupling window are symmetrically arranged with respect to the first common wall.

As an optional implementation, the first common wall and the second common wall are located in the same plane.

As an optional implementation, the first coupling window is located in the middle of the first metal diaphragm along the third direction, and the second coupling window is located in the middle of the second metal diaphragm along the third direction.

As an optional implementation, the length of the second common wall along the second direction is greater than the length of the first common wall along the second direction, and the length of the second common wall along the third direction is less than half the waveguide wavelength corresponding to the center frequency of the filter.

As an optional implementation, the waveguide bandpass filter is in a rectangular parallelepiped shape.

In a second aspect, the present invention further provides an electrical device, comprising the waveguide bandpass filter in any one of the first aspects.

The waveguide bandpass filter provided by the present invention comprises a first waveguide cavity and a second waveguide cavity, wherein the first waveguide cavity comprises an input waveguide cavity and a first resonant cavity, and the second waveguide cavity comprises an output waveguide cavity and a second resonant cavity; a first common wall is provided between the input waveguide cavity and the output waveguide cavity so that the input waveguide cavity and the output waveguide cavity are adjacent to each other along a first direction, and a second common wall is provided between the first resonant cavity and the second resonant cavity so that the first resonant cavity and the second resonant cavity are adjacent to each other along the first direction; in the second direction, the input waveguide cavity and the first resonant cavity are isolated by a first metal diaphragm, and the output waveguide cavity and the second resonant cavity are isolated by a second metal diaphragm; the middle of the second common wall is A first slot extending along a third direction is provided in the middle of the second common wall, the first slot connects the first resonant cavity and the second resonant cavity, and the length of the first slot along the third direction is equal to half of the free space wavelength corresponding to the center frequency of the filter; a first coupling window connecting the input waveguide cavity and the first resonant cavity is provided on the first metal diaphragm, and a second coupling window connecting the output waveguide cavity and the second resonant cavity is provided on the second metal diaphragm; wherein the cavity wall of the input waveguide cavity opposite to the first metal diaphragm serves as the input end of the filter, and the cavity wall of the output waveguide cavity opposite to the second metal diaphragm serves as the output end of the filter, and the first direction, the second direction and the third direction are perpendicular to each other. The waveguide bandpass filter provided by the present invention is provided with a first slot in the middle of the second common wall, and the first slot can not only couple the first resonant cavity and the second resonant cavity, but also can be used as a first-order resonator. Therefore, compared with the traditional three-cavity three-order cascade waveguide bandpass filter, the waveguide bandpass filter provided by the present invention only needs to use two resonant cavities to achieve the response and function of the third-order bandpass filter, reducing the use of the first-order resonant cavity, making the structure of the filter more compact.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a schematic diagram of the overall structure of a waveguide bandpass filter provided by an embodiment of the present invention;

FIG2 is a front view of FIG1 ;

FIG3 is a top view of FIG1 ;

FIG4 is a side view of FIG1 ;

FIG5 is a schematic diagram of a coupling path of a waveguide bandpass filter provided in an embodiment of the present invention;

6 is a graph showing changes in transmission coefficient and reflection coefficient of a waveguide bandpass filter with a first slot at different frequencies provided by an embodiment of the present invention;

FIG7 is a graph showing changes in transmission coefficient and reflection coefficient of a waveguide bandpass filter with a first slot and a second slot at different frequencies provided by an embodiment of the present invention.

Description of reference numerals:

100 - filter;

110-first waveguide cavity;

111-input waveguide cavity;

112-first resonant cavity;

120-second waveguide cavity;

121-output waveguide cavity;

122-second resonant cavity;

130- first common wall;

140 - second common wall;

141-First gap;

142-Second gap;

150-first metal diaphragm;

151-first coupling window;

160- second metal diaphragm;

161-second coupling window;

170-input terminal;

180- output terminal;

Y-first direction;

Z-second direction;

X-third direction.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the application, the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

The current waveguide bandpass filter mainly realizes broadband design by cascading multiple single-mode resonant cavities. However, the existing cascade design will greatly increase the volume of the filter as the order of the filter cascade increases.

In view of this, the present invention provides a waveguide bandpass filter, including a first waveguide cavity and a second waveguide cavity, the first waveguide cavity including an input waveguide cavity and a first resonant cavity, the second waveguide cavity including an output waveguide cavity and a second resonant cavity; a first common wall is provided between the input waveguide cavity and the output waveguide cavity, so that the input waveguide cavity and the output waveguide cavity are adjacent to each other along a first direction, a second common wall is provided between the first resonant cavity and the second resonant cavity, so that the first resonant cavity and the second resonant cavity are adjacent to each other along the first direction; in the second direction, the input waveguide cavity and the first resonant cavity are isolated by a first metal diaphragm, and the output waveguide cavity and the second resonant cavity are isolated by a second metal diaphragm. The first common wall is isolated by a metal diaphragm; the middle part of the second common wall is provided with a first slit extending along the third direction, the first slit connects the first resonant cavity and the second resonant cavity, and the length of the first slit along the third direction is equal to half of the free space wavelength corresponding to the center frequency of the filter; the first metal diaphragm is provided with a first coupling window connecting the input waveguide cavity and the first resonant cavity, and the second metal diaphragm is provided with a second coupling window connecting the output waveguide cavity and the second resonant cavity; wherein the cavity wall of the input waveguide cavity opposite to the first metal diaphragm serves as the input end of the filter, and the cavity wall of the output waveguide cavity opposite to the second metal diaphragm serves as the output end of the filter. The waveguide bandpass filter provided by the present invention is provided with a first slit in the middle part of the second common wall, the first slit can not only couple the first resonant cavity and the second resonant cavity, but also can be used as a first-order resonator, thereby, only two resonant cavities are needed to realize the response and function of the third-order bandpass filter, reducing the use of the first-order resonant cavity, and making the structure of the filter more compact.

Figure 1 is a schematic diagram of the overall structure of a waveguide bandpass filter provided in an embodiment of the present invention; Figure 2 is a front view of Figure 1; Figure 3 is a top view of Figure 1; Figure 4 is a side view of Figure 1; Figure 5 is a schematic diagram of the coupling path of the waveguide bandpass filter provided in an embodiment of the present invention; Figure 6 is a diagram showing the changes in the transmission coefficient and reflection coefficient of the waveguide bandpass filter with a first slot at different frequencies provided in an embodiment of the present invention; Figure 7 is a diagram showing the changes in the transmission coefficient and reflection coefficient of the waveguide bandpass filter with a first slot and a second slot at different frequencies provided in an embodiment of the present invention. With reference to FIGS. 1 to 7 , an embodiment of the present invention provides a waveguide bandpass filter 100, comprising a first waveguide cavity 110 and a second waveguide cavity 120, wherein the first waveguide cavity 110 comprises an input waveguide cavity 111 and a first resonant cavity 112, and the second waveguide cavity 120 comprises an output waveguide cavity 121 and a second resonant cavity 122; a first common wall 130 is provided between the input waveguide cavity 111 and the output waveguide cavity 121, so that the input waveguide cavity 111 and the output waveguide cavity 121 are adjacent to each other along a first direction Y, and a second common wall 140 is provided between the first resonant cavity 112 and the second resonant cavity 122, so that the first resonant cavity 112 and the second resonant cavity 122 are adjacent to each other along the first direction Y; in the second direction Z, the input waveguide cavity 111 and the first resonant cavity 112 are isolated by a first metal diaphragm 150, and the output waveguide cavity 121 and the second resonant cavity 122 are isolated by a second metal diaphragm 160 The first common wall 140 is provided with a first slot 141 extending along the third direction X in the middle thereof, the first slot 141 connecting the first resonant cavity 112 and the second resonant cavity 122, and the length of the first slot 141 along the third direction X is equal to half of the free space wavelength corresponding to the center frequency of the filter 100; the first metal diaphragm 150 is provided with a first coupling window 151 connecting the input waveguide cavity 111 and the first resonant cavity 112, and the second metal diaphragm 160 is provided with a second coupling window 161 connecting the output waveguide cavity 121 and the second resonant cavity 122; wherein the cavity wall of the input waveguide cavity 111 opposite to the first metal diaphragm 150 serves as the input end 170 of the filter 100, and the cavity wall of the output waveguide cavity 121 opposite to the second metal diaphragm 160 serves as the output end 180 of the filter 100, and the first direction Y, the second direction Z and the third direction X are perpendicular to each other.

As shown in FIG. 1 , in the above embodiment, the waveguide bandpass filter 100 can be in the shape of a rectangular parallelepiped as a whole. It can be understood that energy can enter from the input end 170 , enter the first resonant cavity 112 through the first coupling window 151 , enter the second resonant cavity 122 from the first gap 141 , and then pass through the second coupling window 161 before being output from the output end 180 .

The first coupling window 151 and the second coupling window 161 can be symmetrically arranged about the first common wall 130, and the first coupling window 151 and the second coupling window 161 can be symmetrically arranged about the first common wall 130, and the first coupling window 151 is located in the middle of the first metal diaphragm 150 along the third direction X, and the second coupling window 161 is located in the middle of the second metal diaphragm 160 along the third direction X, so as to ensure uniform energy transmission. The sizes of the first coupling window 151 and the second coupling window 161 can be set according to actual needs. The first common wall 130 and the second common wall 140 can be located in the same plane.

The waveguide bandpass filter 100 provided in an embodiment of the present invention has a first slit 141 formed in the middle of the second common wall 140. The first slit 141 can enable coupling between the first resonant cavity 112 and the second resonant cavity 122, and the first slit 141 itself can also be used as a first-order resonator. Therefore, compared with the traditional three-cavity three-order cascade waveguide bandpass filter 100, the waveguide bandpass filter 100 provided in the present invention only needs to use two resonant cavities to achieve the response and function of third-order bandpass filtering, reducing the use of the first-order resonant cavity, making the structure of the filter 100 more compact.

In the above embodiment, a second slit 142 is further provided on the second common wall 140 to connect the first resonant cavity 112 and the second resonant cavity 122. The second slit 142 extends along the third direction X. The second slit 142 and the first slit 141 are spaced apart along the second direction Z. The length of the second slit 142 along the third direction X is less than the length of the first slit 141 along the third direction X. The second slit 142 can introduce an additional coupling path, thereby introducing an additional transmission zero point at high frequency, thereby improving the suppression level of the upper sideband. The position of the high-frequency zero point can be flexibly controlled by adjusting the length, width and distance of the second slit 142 from the first slit 141. Specifically, the second slit 142 can be provided between the first slit 141 and the second metal plate.

In the above embodiment, the length of the second common wall 140 along the second direction Z can be greater than the length of the first common wall 130 along the second direction Z, and the length of the second common wall 140 along the third direction X can be less than half the waveguide wavelength corresponding to the center frequency of the filter 100 .

The waveguide bandpass filter 100 provided in the embodiment of the present invention is obtained by etching a half-wavelength coupling slot (first slot 141) on the central wide wall of two waveguide resonant cavities that are symmetrical along the wide wall (Y-axis direction). The half-wavelength coupling slot can generate an additional resonance point in the passband while providing energy coupling between the two waveguide resonant cavities, so that a third-order bandpass filter response can be easily obtained using two waveguide resonant cavities.

As shown in FIG5 , S represents the input end 170, L represents the output end 180, 1 represents the first resonant cavity 112, 2 represents the first slot 141, 3 represents the second resonant cavity 122, _Ms1 is the normalized coupling coefficient between the input end 170 and the first resonant cavity 112, _M3L is the normalized coupling coefficient between the second resonant cavity 122 and the output end 180, _M12 is the normalized coupling coefficient between the first resonant cavity 112 and the first slot 141, _{M23 is} the normalized coupling coefficient between the first slot 141 and the second resonant cavity 122, and _{M13 is} the normalized cross-coupling coefficient between the non-adjacent first resonant cavity 112 and the second resonant cavity 122 brought by the first slot 141.

The calculation formulas for the above parameters are as follows:

In the above formula, FBW is 3 dB (3 decibel) relative bandwidth, and the specific calculation method is: 3 dB bandwidth/center frequency; k ₁₂ ( k _ii+1 when i is 1) is the coupling coefficient between the first resonant cavity 112 and the first slot 141, and k ₂₃ ( k _ii+1 when i is 2) is the coupling coefficient between the first slot 141 and the second resonant cavity 122.

It can be understood that in addition to providing coupling between the first resonant cavity 112 and the second resonant cavity 122 and being used as a primary resonator, the first slot 141 also provides an additional cross-coupling path between two non-adjacent resonant cavities; and the external quality factors of the input end 170 and the output end 180 can be controlled by changing the sizes of the first coupling window 151 and the second coupling window 161, thereby changing the values of _Ms1 and _M3L ; and the values of _M12 , _M23 and _M13 can be changed by adjusting the width of the first slot 141 and the distance between the first slot 141 and the first resonant cavity 112 along the second direction Z.

As shown in FIG6 , the abscissa is frequency (in gigahertz, GHz), and the ordinate is amplitude values (in decibels, dB) corresponding to the reflection coefficient (S ₁₁ ) and the transmission coefficient (S ₂₁ ) of the waveguide bandpass filter with the first slot 141 , wherein the curve marked with a square shape is a curve showing a change in the reflection coefficient (S ₁₁ ) with frequency, and the curve marked with a triangle shape is a curve showing a change in the transmission coefficient (S ₂₁ ) with frequency. It can be seen from the curve showing a change in the reflection coefficient (S ₁₁ ) with frequency in the figure that the waveguide bandpass filter with the first slot 141 exhibits a third-order bandpass filtering response, i.e., there are three transmission poles in the passband, and the return loss value is lower than -18 dB. It can be seen from the curve showing a change in the transmission coefficient (S ₂₁ ) with frequency in the figure that the minimum insertion loss in the passband is 0.005 dB, and there is a transmission zero in the upper sideband (about 4 GHz), and the upper sideband out-of-band suppression level is ≥28 dB.

As shown in FIG7 , the abscissa is frequency (in gigahertz, GHz), and the ordinate is amplitude values (in decibel, dB) corresponding to the reflection coefficient (S ₁₁ ) and the transmission coefficient (S ₂₁ ) of the waveguide bandpass filter with the first slot 141 and the second slot 142. The curve marked with a square is the curve of the reflection coefficient (S ₁₁ ) changing with frequency, and the curve marked with a triangle is the curve of the transmission coefficient (S ₂₁ ) changing with frequency. It can be seen from the curve of the reflection coefficient (S ₁₁ ) changing with frequency that the waveguide bandpass filter with the first slot 141 and the second slot 142 exhibits a third-order bandpass filtering response, that is, there are three transmission poles in the passband, and the return loss value is lower than -20 dB. It can be seen from the curve of the transmission coefficient (S ₂₁ ) changing with frequency that the minimum insertion loss in the passband is 0.0001 dB, compared with the transmission coefficient (S _{21 )} of the waveguide bandpass filter with the first slot 141 shown in FIG6 . ) versus frequency, it can be seen that due to the introduction of the second slot 142, an additional transmission zero point is generated in the upper sideband, so that the out-of-band suppression level of the upper sideband is improved (≥30 dB).

The waveguide bandpass filter 100 provided by the embodiment of the present invention comprises a first waveguide cavity 110 and a second waveguide cavity 120, wherein the first waveguide cavity 110 comprises an input waveguide cavity 111 and a first resonant cavity 112, and the second waveguide cavity 120 comprises an output waveguide cavity 121 and a second resonant cavity 122; a first common wall 130 is provided between the input waveguide cavity 111 and the output waveguide cavity 121, so that the input waveguide cavity 111 and the output waveguide cavity 121 are adjacent to each other along a first direction Y, and a second common wall 140 is provided between the first resonant cavity 112 and the second resonant cavity 122, so that the first resonant cavity 112 and the second resonant cavity 122 are adjacent to each other along the first direction Y; in the second direction Z, the input waveguide cavity 111 and the first resonant cavity 112 are isolated by a first metal diaphragm 150, and the output waveguide cavity 121 and the second resonant cavity 122 are isolated by a second metal diaphragm 160; the second common wall 140 is provided between the input waveguide cavity 111 and the output waveguide cavity 121 and the second resonant cavity 122 A first slot 141 extending along the third direction X is provided in the middle of the wall 140, the first slot 141 connects the first resonant cavity 112 and the second resonant cavity 122, and the length of the first slot 141 along the third direction X is equal to half of the free space wavelength corresponding to the center frequency of the filter 100; a first coupling window 151 connecting the input waveguide cavity 111 and the first resonant cavity 112 is provided on the first metal diaphragm 150, and a second coupling window 161 connecting the output waveguide cavity 121 and the second resonant cavity 122 is provided on the second metal diaphragm 160; wherein, the cavity wall of the input waveguide cavity 111 opposite to the first metal diaphragm 150 serves as the input end 170 of the filter 100, and the cavity wall of the output waveguide cavity 121 opposite to the second metal diaphragm 160 serves as the output end 180 of the filter 100, and the first direction Y, the second direction Z and the third direction X are perpendicular to each other.

The waveguide bandpass filter 100 provided in the embodiment of the present invention has a first slot 141 in the middle of the second common wall 140. The first slot 141 can not only couple the first resonant cavity 112 and the second resonant cavity 122, but also can be used as a first-order resonator. Therefore, compared with the traditional three-cavity three-order cascade waveguide bandpass filter 100, the waveguide bandpass filter 100 provided in the present invention only needs to use two resonant cavities to achieve the response and function of the third-order bandpass filter, reducing the use of the first-order resonant cavity, making the structure of the filter 100 more compact. In addition, the waveguide bandpass filter 100 provided in the embodiment of the present invention also has the performance advantages of miniaturization, low insertion loss and high selectivity. Its minimum insertion loss in the band is about 0.0001dB, the upper sideband out-of-band suppression level is ≥30dB, and the high-frequency zero point is controllable.

In addition, an embodiment of the present invention further provides an electrical device, the electrical device comprising the waveguide bandpass filter 100 of any one of the above embodiments, the waveguide bandpass filter 100 comprising a first waveguide cavity 110 and a second waveguide cavity 120, the first waveguide cavity 110 comprising an input waveguide cavity 111 and a first resonant cavity 112, the second waveguide cavity 120 comprising an output waveguide cavity 121 and a second resonant cavity 122; a first common wall 130 is provided between the input waveguide cavity 111 and the output waveguide cavity 121, so that the input waveguide cavity 111 and the output waveguide cavity 121 are adjacent to each other along a first direction Y, a second common wall 140 is provided between the first resonant cavity 112 and the second resonant cavity 122, so that the first resonant cavity 112 and the second resonant cavity 122 are adjacent to each other along the first direction Y; in the second direction Z, the input waveguide cavity 111 and the first resonant cavity 112 are isolated by a first metal diaphragm 150, and the output waveguide cavity 121 is adjacent to each other along a first direction Y. The guide cavity 121 and the second resonant cavity 122 are isolated by the second metal diaphragm 160; a first slot 141 extending along the third direction X is opened in the middle of the second common wall 140, the first slot 141 connects the first resonant cavity 112 and the second resonant cavity 122, and the length of the first slot 141 along the third direction X is equal to half of the free space wavelength corresponding to the center frequency of the filter 100; a first coupling window 151 connecting the input waveguide cavity 111 and the first resonant cavity 112 is provided on the first metal diaphragm 150, and a second coupling window 161 connecting the output waveguide cavity 121 and the second resonant cavity 122 is provided on the second metal diaphragm 160; wherein, the cavity wall of the input waveguide cavity 111 opposite to the first metal diaphragm 150 serves as the input end 170 of the filter 100, and the cavity wall of the output waveguide cavity 121 opposite to the second metal diaphragm 160 serves as the output end 180 of the filter 100.

The waveguide bandpass filter 100 has a first slot 141 in the middle of the second common wall 140. The first slot 141 can couple the first resonant cavity 112 and the second resonant cavity 122. The first slot 141 itself can also be used as a primary resonator. The waveguide bandpass filter 100 only needs to use two resonant cavities to achieve the response and function of a third-order bandpass filter, thereby reducing the use of a primary resonant cavity and making the structure of the electrical equipment more compact.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A waveguide bandpass filter, characterized in that it comprises a first waveguide cavity and a second waveguide cavity, wherein the first waveguide cavity comprises an input waveguide cavity and a first resonant cavity, and the second waveguide cavity comprises an output waveguide cavity and a second resonant cavity; a first common wall is provided between the input waveguide cavity and the output waveguide cavity so that the input waveguide cavity and the output waveguide cavity are adjacent to each other along a first direction, and a second common wall is provided between the first resonant cavity and the second resonant cavity so that the first resonant cavity and the second resonant cavity are adjacent to each other along the first direction; In the second direction, the input waveguide cavity and the first resonant cavity are isolated by a first metal diaphragm, and the output waveguide cavity and the second resonant cavity are isolated by a second metal diaphragm; A first slit extending along a third direction is formed in the middle of the second common wall, the first slit connects the first resonant cavity and the second resonant cavity, and the length of the first slit along the third direction is equal to half of the free space wavelength corresponding to the center frequency of the filter; The first metal diaphragm has a first coupling window connecting the input waveguide cavity and the first resonant cavity, and the second metal diaphragm has a second coupling window connecting the output waveguide cavity and the second resonant cavity; The cavity wall of the input waveguide cavity opposite to the first metal diaphragm serves as the input end of the filter, the cavity wall of the output waveguide cavity opposite to the second metal diaphragm serves as the output end of the filter, and the first direction, the second direction and the third direction are perpendicular to each other. 2. The waveguide bandpass filter according to claim 1 is characterized in that a second slit connecting the first resonant cavity and the second resonant cavity is also opened on the second common wall, the second slit extends along the third direction, the second slit is spaced apart from the first slit along the second direction, and the length of the second slit along the third direction is less than the length of the first slit along the third direction. 3 . The waveguide bandpass filter according to claim 2 , wherein the second gap is located between the first gap and the first metal diaphragm. 4 . The waveguide bandpass filter according to claim 3 , wherein the first metal diaphragm and the second metal diaphragm are symmetrically arranged about the first common wall. 5 . The waveguide bandpass filter according to claim 4 , wherein the first coupling window and the second coupling window are symmetrically arranged about the first common wall. 6 . The waveguide bandpass filter according to claim 5 , wherein the first common wall and the second common wall are located in the same plane. 7. The waveguide bandpass filter according to claim 6, characterized in that the first coupling window is located in the middle of the first metal diaphragm along the third direction, and the second coupling window is located in the middle of the second metal diaphragm along the third direction. 8. The waveguide bandpass filter according to claim 7 is characterized in that the length of the second common wall along the second direction is greater than the length of the first common wall along the second direction, and the length of the second common wall along the third direction is less than half the waveguide wavelength corresponding to the center frequency of the filter. 9. The waveguide bandpass filter according to any one of claims 1 to 8, characterized in that the waveguide bandpass filter is in a rectangular parallelepiped shape. 10. An electrical device, characterized by comprising the waveguide bandpass filter according to any one of claims 1 to 9.