CN212908003U

CN212908003U - Cavity filter suitable for planar circuit integration

Info

Publication number: CN212908003U
Application number: CN202022192573.2U
Authority: CN
Inventors: 马长春; 袁海斌
Original assignee: Hangzhou Yongxie Technology Co ltd
Current assignee: Hangzhou Yongxie Technology Co ltd
Priority date: 2020-09-29
Filing date: 2020-09-29
Publication date: 2021-04-06
Anticipated expiration: 2030-09-29

Abstract

The utility model discloses a cavity filter suitable for planar circuit integration, which comprises a metal bottom plate, a circuit board and a cavity shell, wherein the upper end surface of the metal bottom plate is provided with two reflecting cavities which are symmetrically arranged, the circuit board is positioned at the upper end of the metal bottom plate, and is fixedly connected with the metal bottom plate, the cavity body shell is positioned above the circuit board, an air cavity is arranged in the cavity body shell, the air cavity comprises a plurality of resonant cavities and two conducting cavities, a plurality of clapboards are fixedly arranged in the air cavity, the length of the clapboards is different, the resonant cavities are positioned between two adjacent clapboards, the conducting cavities are symmetrically positioned at two ends of the resonant cavities, one side of the lower end surface of the conducting cavity penetrates through the lower end surface of the cavity body shell, and be located directly over the reflection chamber, the utility model discloses rational in infrastructure, the size is little, and space occupancy is low, and the performance is high, makes things convenient for some miniaturized and the equipment that integrates to use.

Description

Cavity filter suitable for planar circuit integration

Technical Field

The utility model relates to a 5G millimeter wave communication device field, in particular to cavity filter suitable for planar circuit is integrated.

Background

In the field of 5G millimeter wave communication equipment, due to the requirements of high data throughput, signal bandwidth, low delay and the like, the requirements on the integration level, miniaturization and the like of the communication equipment are high. In the manufacturing process of the communication device, the cavity filter is a three-dimensional device, the circuit board in the radio frequency front-end device is designed by adopting a planar circuit, meanwhile, the millimeter wave signal transmitted by the cavity filter is a TE mode, a signal port of the millimeter wave signal is a waveguide port or a coaxial port converted by other devices, and the millimeter wave signal transmitted by the circuit board of the radio frequency front-end device is a TEM mode or a quasi-TEM mode, so that an additional adapter and a radio frequency cable are often required to be added to connect the radio frequency circuit board and the cavity filter. This results in an increase in the overall size of the rf front-end equipment, as well as some additional signal loss due to the introduction of connectors and rf cables.

However, the existing cavity filter has a complex filtering structure, so that the shape of the cavity filter is large, the space occupancy rate of the cavity filter is also large, the miniaturization and the centralization of equipment are not facilitated, and the small-sized cavity filter has insufficient out-of-band rejection capability and high signal loss. In view of the above problems, a solution is proposed as follows.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a cavity filter suitable for planar circuit is integrated has and can directly paste the dress on the circuit board of radio frequency front end equipment, is favorable to the miniaturization of radio frequency front end equipment and integrates, reduces signal loss simultaneously, satisfies 5G millimeter wave communication's high performance requirement's advantage.

The above technical purpose of the present invention can be achieved by the following technical solutions:

the utility model provides a cavity filter suitable for planar circuit is integrated, includes metal soleplate, circuit board and cavity shell, metal soleplate's up end is equipped with two reflection chambeies, two the reflection chamber is the symmetry and sets up, the circuit board is located metal soleplate's upper end, and with metal soleplate fixed connection, the cavity shell is located the top of circuit board, be equipped with the air chamber in the cavity shell, the transmission range of air chamber restriction signal ripples, a plurality of baffles have set firmly in the air chamber, and is a plurality of the length of baffle is different, baffle length is used for filtering high mode signal, and is a plurality of interval between the baffle is different, interval between the baffle is used for filtering low mode signal.

By adopting the technical scheme, the two ends of the circuit board are respectively connected with external circuits, the signal mode conversion circuit can convert signals into modes capable of being transmitted in the cavity, the spacing width among the plurality of clapboards determines the lower limit of signal frequency capable of passing through the clapboard, the signals with the frequency lower than the lower limit are filtered, and the distance between the lower ends of the clapboards and the bottom surface of the air cavity can filter high-order mode signals and signals with the working frequency higher than the working frequency, so that the output signals are the required working signal frequency.

Preferably, the reflection cavity is rectangular, and four corners of the reflection cavity are arc-shaped.

By adopting the technical scheme, the metal base is made of metal, so that the bottom surface of the reflection cavity can reflect signal waves, and the reflection cavity with the depth of a quarter wavelength can counteract the interference of working waves, thereby obtaining a stable signal.

Preferably, one side of the two outermost partition plates is a conduction cavity, signal waves can be transmitted in the conduction cavity, caulking grooves are symmetrically formed in two ends of the cavity shell, a through groove is formed in the lower end of the caulking groove, the through groove penetrates through the side wall of the cavity shell and is communicated with one side of the conduction cavity, and part of the signal mode conversion circuit enters the inside of the conduction cavity through the through groove.

By adopting the technical scheme, the two ends of the cavity shell are communicated with the outside through the two through grooves, so that signals on an external circuit can enter the cavity shell in a lossless manner, and are transmitted out of the cavity shell in a lossless manner after being processed, and the signals are transmitted more stably.

Preferably, a resonant cavity is arranged between two adjacent partition plates, the widths of the resonant cavities are different, the width of the resonant cavity in the middle is the smallest, and the widths of the resonant cavities on the side edges are sequentially increased and are bilaterally symmetrical.

By adopting the technical scheme, the wider the width of the resonant cavity is, the lower the frequency of the wave which can be inhibited is, and the width of the resonant cavity is gradually reduced, so that the lowest frequency of the wave which can be conducted is gradually increased, and the low frequency of the wave which is conducted is the same as the low frequency of a required signal.

Preferably, the plurality of the partition plates are bilaterally symmetrical, and the lengths of the plurality of the partition plates are sequentially reduced from the middle to two sides.

By adopting the technical scheme, the longer the partition plate is, the smaller the gap between the lower end of the partition plate and the bottom surface of the air cavity is, the larger the coupling gap is, the higher the frequency of the signal wave passing through the gap is, the gradually reduced coupling gap can inhibit the highest frequency of the signal wave passing through the gap, so that the signal wave lower than the highest frequency can pass through the gap, and the coupling gap and the width of the resonant cavity jointly act to form a band-pass filter, so that the frequency of the signal wave finally transmitted is the required frequency.

Preferably, the cavity housing is fixedly connected with the circuit board in a welding mode, and the metal bottom plate is fixedly connected with the lower end of the circuit board in a welding mode.

By adopting the technical scheme, the cavity shell, the circuit board and the metal bottom plate are fixed in an electric glue welding mode in sequence, so that the three parts can not be separated, and the signals can be better processed.

Preferably, the side wall of the bottom plate is fixedly provided with a plurality of fixing pieces, and the fixing pieces are provided with fixing holes.

By adopting the technical scheme, one end of the external fasteners such as the screws can penetrate through the fixing holes, so that the fixing sheet can be fixed in an external circuit, and the filter is fixed.

By adopting the technical scheme, the micro-strip-to-waveguide circuit can convert a quasi-TEM mode transmitted by a planar circuit into a TE mode, so that the quasi-TEM mode can be transmitted in the cavity, and meanwhile, the length of the signal is effectively controlled, so that the circuit structure can only transmit a required working frequency signal.

Preferably, two connection sockets are symmetrically and fixedly arranged on two sides of the upper end surface of the circuit board, and the two connection sockets are electrically connected with two connection ends of the microstrip-to-waveguide circuit respectively.

By adopting the technical scheme, the external lead is inserted into the connecting seat, so that the communication between an external circuit and the microstrip-to-waveguide circuit can be realized, and the connection efficiency of the circuit is improved.

Preferably, the upper end face of the circuit board is provided with a plurality of circuit partitions, and the microstrip-to-waveguide circuit is located in one of the circuit partitions.

By adopting the technical scheme, the millimeter wave circuit can be designed in each circuit partition, so that all circuits can be concentrated on one circuit board, and the miniaturization and integration of equipment are realized.

This scheme adopts the integrated form design, filters the signal wave through simple structure, makes the product realize integrating and the miniaturization, and the installation of the product of being convenient for on the small-size equipment is used.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment;

fig. 2 is a sectional view of the embodiment.

Reference numerals: 1. a metal base plate; 2. a circuit board; 3. a cavity housing; 4. a reflective cavity; 5. a resonant cavity; 6. a communicating cavity; 7. a partition plate; 8. caulking grooves; 9. a through groove; 10. a fixing sheet; 11. a fixing hole; 12. and connecting the socket.

Detailed Description

The following is only the preferred embodiment of the present invention, the protection scope is not limited to this embodiment, and all technical solutions belonging to the idea of the present invention should belong to the protection scope of the present invention. It should also be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and such modifications and decorations should also be regarded as the protection scope of the present invention.

As shown in fig. 1 and 2, a cavity filter suitable for planar circuit integration includes a metal base plate 1, a circuit board 2, and a cavity housing 3. The cavity shell 3, the circuit board 2 and the metal bottom plate 1 are fixedly connected in sequence in an electric glue welding mode, and the three cannot be separated.

The upper end face of the circuit board 2 is provided with a plurality of circuit subareas, one of the circuit subareas is internally provided with a microstrip-to-waveguide circuit, and the circuit can convert a quasi-TEM mode transmitted by a planar circuit into a TE mode transmitted in the cavity, so that signals can be transmitted in the cavity shell 3.

Be equipped with the air chamber in cavity shell 3, the air chamber includes a plurality of resonant cavities 5 and two lead to chamber 6, and the signal wave gets into from a lead to chamber 6, through a plurality of resonant cavities 5 to spread from another lead to chamber 6 department. The signal waves are processed by several resonator cavities 5.

The widths of the resonant cavities 5 are different, the resonant cavities 5 with different widths can filter low-frequency signals of signal waves, and the larger the width of the resonant cavity 5 is, the smaller the frequency of the filtered low-frequency signals is. The width of the resonant cavity 5 positioned in the middle is the smallest, and the widths of the resonant cavities 5 positioned on the side edges are sequentially increased and are symmetrical left and right. When signal waves enter the resonant cavity 5 from one side and are transmitted towards the other side of the resonant cavity 5, the resonant cavities 5 can gradually filter the low-frequency mode segment of the signal waves, so that the lowest frequency which can be transmitted by the signal waves gradually rises in the transmission process of the signal waves until the low frequency of the signal waves is equal to the low frequency of the required signal, and the filtering of the low-frequency band of the signal is completed.

A plurality of clapboards 7 are fixedly arranged in the air cavity, the clapboards 7 are symmetrical left and right, and the lengths of the clapboards 7 are gradually reduced from the middle to two sides. The spacers 7 of different lengths have different gaps between their lower ends and the air cavity, which are called coupling gaps. The high-frequency mode segments of the signal wave passing through the coupling gap are filtered. The larger the coupling gap, the higher the highest frequency of the signal wave that can pass through the coupling gap. The gradually reduced coupling gap can gradually filter the high-frequency mode section of the signal wave, so that the filtering of the high-frequency mode section of the signal wave is completed.

A resonant cavity 5 is arranged between two adjacent partition plates 7, when a signal wave passes through the resonant cavity 5, the resonant cavity 5 and the partition plates 7 act together to filter the high frequency band and the low frequency band of the signal wave simultaneously, and therefore the frequency of the finally transmitted signal is the required frequency band.

The conducting cavity 6 is symmetrically arranged at two ends of the resonant cavities 5, the upper end face of the metal bottom plate 1 is symmetrically provided with two reflecting cavities 4, and the conducting cavity 6 is arranged right above the reflecting cavities 4. The microstrip to waveguide circuit on the circuit board 2 has an operating signal. The depth of the reflective cavity 4 is one quarter of the wavelength of the operating signal. When the signal wave starts to transmit, the reflection cavity 4 reflects the signal wave to reduce interference of the signal wave, so that the signal wave is more stable during transmission.

The both ends of cavity shell 3 are symmetrical is equipped with caulking groove 8, and logical groove 9 has been seted up to the lower extreme of caulking groove 8, and logical groove 9 communicates with each other with the one side that switches on chamber 6. Both ends of the microstrip-to-waveguide circuit are provided with a connecting end, and part of the two connecting ends penetrate through the through groove 9 and are communicated with the outside. Signals on an external circuit can enter the cavity shell 3 through the through groove 9, and the cavity shell 3 is prevented from influencing the transmission of signal waves. Two connecting sockets 12 are symmetrically and fixedly arranged on the upper end face of the circuit board 2, and the two connecting sockets 12 are electrically connected with two connecting ends of the microstrip-to-waveguide circuit respectively. The two connection sockets 12 can conveniently connect the microstrip waveguide circuit with an external circuit, can be disassembled and assembled, and are convenient for connecting the circuit.

The side wall of the bottom plate is fixedly provided with a plurality of fixing pieces 10, and the fixing pieces 10 are provided with fixing holes 11. One end of a fastener such as a screw is inserted through the fixing hole 11 and fixed with an external device, thereby completing the installation and fixation of the filter.

The working principle is as follows: the working frequency band of the filter is set to be 20-25GHz, and the depth of the reflecting cavity 4 is set to be 1.546 mm. The external equipment is connected with the microstrip-to-waveguide circuit, the external equipment generates a signal wave, and the microstrip-to-waveguide circuit couples the signal wave to the microstrip planar circuit and transmits the signal wave in the cavity shell 3. When the signal wave passes through the resonant cavity 5, the coupling width between the resonant cavities 5 is smaller than the width of the waveguide, and the signal transmission below 20GHz is inhibited. The height of the coupling gap is sequentially reduced, and the coupling gap is symmetrical left and right, so that transmission of a high-order mode and transmission of signals larger than 25GHZz are restrained. Thereby forming a 20-25GHz band-pass filter.

Claims

1. A cavity filter suitable for planar circuit integration comprises a metal base plate (1), a circuit board (2) and a cavity shell (3), it is characterized in that the upper end surface of the metal bottom plate (1) is provided with two reflecting cavities (4), the two reflecting cavities (4) are symmetrically arranged, the circuit board (2) is positioned at the upper end of the metal bottom plate (1), and is fixedly connected with the metal bottom plate (1), the cavity shell (3) is positioned above the circuit board (2), an air cavity is arranged in the cavity shell (3) and limits the transmission range of signal waves, a plurality of clapboards (7) are fixedly arranged in the air cavity, the length of the clapboards (7) is different, the length of the partition boards (7) is used for filtering high-mode signals, the intervals among the partition boards (7) are different, and the intervals among the partition boards (7) are used for filtering low-mode signals.

2. The cavity filter for planar circuit integration according to claim 1, wherein the reflective cavity (4) is rectangular, and four corners of the reflective cavity (4) are curved.

3. The cavity filter suitable for planar circuit integration according to claim 2, wherein one side of the two outermost partition plates is a conducting cavity (6), the conducting cavity (6) can transmit signal waves, caulking grooves (8) are symmetrically arranged at two ends of the cavity housing (3), a through groove (9) is formed at the lower end of the caulking groove (8), and the through groove (9) penetrates through the side wall of the cavity housing (3) and is communicated with one side of the conducting cavity (6).

4. The cavity filter for planar circuit integration according to claim 3, wherein a resonant cavity (5) is disposed between two adjacent partition plates (7), the resonant cavity (5) is capable of filtering low-frequency signal waves, a plurality of the resonant cavities (5) have different widths, the resonant cavity (5) located at a middle position has a smallest width, and the resonant cavities (5) located at lateral sides have successively larger widths and are bilaterally symmetric.

5. The cavity filter for planar circuit integration according to claim 4, wherein a plurality of the partitions (7) are symmetrical left and right, and the lengths of the partitions (7) decrease from the middle to both sides.

6. The cavity filter suitable for planar circuit integration according to claim 5, wherein the cavity housing (3) is fixedly connected with the circuit board (2) by welding, and the metal base plate (1) is fixedly connected with the lower end of the circuit board (2) by welding.

7. The cavity filter suitable for planar circuit integration according to claim 6, wherein a plurality of fixing pieces (10) are fixedly arranged on the side wall of the bottom plate, and fixing holes (11) are formed on the fixing pieces (10).

8. The cavity filter for planar circuit integration according to claim 7, wherein two connection sockets (12) are symmetrically and fixedly arranged on both sides of the upper end surface of the circuit board (2).

9. The cavity filter for planar circuit integration according to claim 8, wherein the upper end surface of the circuit board (2) is provided with a plurality of circuit partitions.