Trapezoidal tap interdigital filter

Abstract

The utility model relates to a trapezoidal tap interdigital filter, and particularly relates to the technical field of filters, the trapezoidal tap interdigital filter comprises a shell, the top of the shell is connected with a cover plate through a bolt, the shell is matched with the cover plate, a substrate is arranged in the middle between the shell and the cover plate, one end of the shell is provided with an input interface, and the other end of the shell is provided with an output interface. An input interface is formed in the shell, an output interface is formed in the side, away from the input interface, of the shell, the input interface and the output interface are located on the same straight line, resonators are arranged in the middle of the substrate, ground holes are formed in the ends of the resonators, and the input interface and the output interface are connected with the resonators on the two sides through tap structures. The tap structure comprises an external connection part, a transition part and a connection part. The mode of optimizing the tap structure is utilized to ensure that key performance indexes such as frequency selectivity, insertion loss, retardation inhibition and the like meet high-standard requirements, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of filter technology, and in particular to a trapezoidal tapped interdigital filter. Background Technology

[0002] A filter is an electronic device or circuit whose main function is to selectively allow certain frequencies to pass through an electrical signal while suppressing others. Its working principle is similar to a sieve, but it targets electrical signals rather than physical objects.

[0003] A search revealed an existing patent (publication number: CN117543173A) that discloses a filter, including a housing, a fixing block, and a transmission component. The housing has a connector groove, a resonant groove, a transmission groove, and a limiting groove. The transmission groove passes through the limiting groove, with one end connected to the connector groove and the other end connected to the resonant groove. The transmission groove is divided into a first groove region and a second groove region that are interconnected along its depth direction. The opening of the transmission groove is located on the side of the first groove region opposite to the second groove region. The width of the first groove region is smaller than the width of the second groove region. The fixing block is inserted into the limiting groove and has a mounting channel. The transmission component is disposed in the second groove region and passes through the mounting channel. Supported by the fixing block, the transmission component is spaced apart from the bottom and walls of the transmission groove. In this invention, the first and second groove regions of the transmission groove form a T-shaped groove. While ensuring that the second groove region can accommodate the transmission component, the volume of the transmission groove is effectively reduced, and the anti-interference capability is improved. During the development of this application, the inventors discovered the following problems with the existing technology:

[0004] Currently, the taps of interdigital filters with microstrip line structures used in the market are generally rectangular taps. They are simple in structure and widely used. However, when the performance requirements are high or the quality factor Q is large, traditional rectangular tap interdigital filters may not be able to meet the requirements. Using high-performance materials and special processes to improve the performance of interdigital filters may result in costs exceeding expectations. Utility Model Content

[0005] The purpose of this application is to provide a trapezoidal tapped interdigital filter.

[0006] Firstly, the trapezoidal tapped interdigital filter provided in this application adopts the following technical solution:

[0007] A trapezoidal tapped interdigital filter includes a housing, a cover plate bolted to the top of the housing, the housing and the cover plate being matched, a sealing gasket being provided at the connection between the housing and the cover plate, a substrate being provided in the middle between the housing and the cover plate, an input interface being provided at one end of the housing, an output interface being provided on the side of the housing away from the input interface, the input interface and the output interface being on the same straight line, seven sets of resonators being arranged in the middle of the substrate, the resonators being arranged in an alternating manner, ground holes being provided at the ends of multiple sets of resonators, and both the input interface and the output interface being connected to the resonators on both sides through a tapped structure.

[0008] By adopting the above technical solution, the housing plays a protective and electromagnetic shielding role. The housing has a multi-layer structure, with the outer layer using metal to provide shielding and the cover plate serving as a cover. The housing and cover plate work together to seal and fix the substrate. The electromagnetic coupling between multiple sets of resonators forms multiple resonant units, realizing the frequency selection function. The interdigital structure is compact and suitable for miniaturization design. The input and output interfaces serve to connect to external lines, and the ground hole ensures a good connection between the filter and the system ground.

[0009] The tap structure includes an outer part, a transition part, and a connecting part. One side of the outer part is connected to the transition part, and one side of the transition part is connected to the connecting part. The widths of the outer part, the transition part, and the connecting part decrease sequentially. The transition part is inclined, and the overall shape of the tap structure is a trapezoidal structure.

[0010] By adopting the above technical solution, due to the different impedances of the external part and the connection part, the step-type direct connection will result in a large return loss at the port. According to transmission line theory, a transition part can be added between the two to improve the return loss at the port. The smoother the transition, the smaller the return loss at the port. The connection part can be optimized with different widths and lengths according to the specifications, which increases the optimization space. The closer the tap structure is to the ground terminal, the smaller the quality factor Q of the filter. Therefore, when the relative positions of the tap structures are consistent, the trapezoidal tap interdigital filter has a smaller quality factor Q.

[0011] The width of the external portion corresponds to a 50Ω system impedance. When connected to the outside, the higher the proportion of its length in the entire tap, the smaller the quality factor Q. The impedance values ​​of the external portion and the connection portion are different.

[0012] By adopting the above technical solution, the tap structure composed of the external part, the transition part and the connection part improves the performance parameters of the interdigital filter of the same order, especially the return loss, which is conducive to cost saving and avoids the waste of cost due to high-performance materials or special processes.

[0013] The transition section is a progressive trapezoidal shape, and the connecting section is specifically optimized with different widths and lengths according to the indicators.

[0014] By adopting the above technical solution, and appropriately optimizing the three parts of the trapezoidal interdigital filter tap according to the performance requirements in practical applications, the system performance can be greatly improved. Compared with the common rectangular tap filter, the trapezoidal tap interdigital filter has advantages in both return loss and out-of-band suppression.

[0015] The passband bandwidth of the substrate and resonator is 20-27.5GHz, the relative bandwidth is 30%, the in-band flatness is less than 0.5dB, the passband insertion loss is less than 1.2dB, the return loss is greater than 20dB, the substrate material is RO4003, and the cavity depth is 6mm.

[0016] By adopting the above technical solution, specifically a seventh-order interdigital filter, excellent filtering performance can be achieved through reasonable design of electrode size, selection of dielectric substrate and optimization of tap form.

[0017] The bottom of the housing has a heat-conducting plate, and heat sinks are arranged and connected to the outer wall of the heat-conducting plate.

[0018] By adopting the above technical solution, the heat-conducting sheet plays a role in heat conduction, which can absorb the heat generated during the operation of the device and release the heat through the heat sink, thereby improving the heat dissipation performance of the device. This can effectively reduce the temperature rise of the seventh-order interdigital filter and improve its reliability and stability in high-power applications.

[0019] In summary, this application includes at least one of the following beneficial technical effects:

[0020] 1. The tapped structure, consisting of an external section, a transition section, and a connecting section, improves the performance parameters of interdigital filters of the same order. Due to the different impedances of the external section and the connecting section, a direct step connection will result in a large return loss at the port. According to transmission line theory, a transition section can be added between the two to improve the return loss at the port. The smoother the transition, the smaller the return loss at the port. The connecting section can be optimized with different widths and lengths according to the specifications, increasing the optimization space. The closer the tapped structure is to the ground terminal, the smaller the quality factor Q of the filter. Therefore, when the relative positions of the tapped structures are consistent, the trapezoidal tapped interdigital filter has a smaller quality factor Q. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall connection structure of an embodiment of this application;

[0022] Figure 2This is a schematic diagram of the substrate connection structure according to an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of the connection structure between the tap structure and the resonator in an embodiment of this application;

[0024] Figure 4 This is a comparative structural diagram of two tap types in an embodiment of this application;

[0025] Figure 5 This is a schematic diagram comparing the S-parameters of two tapped interdigital filters according to embodiments of this application;

[0026] Figure 6 This is a schematic diagram of the structure of the housing, cover plate, heat-conducting plate and heat sink in an embodiment of this application.

[0027] Explanation of reference numerals in the attached drawings: 1. Housing; 2. Cover plate; 3. Sealing gasket; 4. Base plate; 5. Input interface; 6. Output interface; 7. Resonator; 8. Ground hole; 9. Tap structure; 10. External part; 11. Transition part; 12. Connection part; 13. Heat-conducting plate; 14. Heat sink. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1 - Appendix Figure 6 This application will be described in further detail below.

[0029] Example: A trapezoidal tapped interdigital filter includes a housing 1, with a cover plate 2 bolted to the top of the housing 1. The housing 1 and the cover plate 2 are fitted together, and a sealing gasket 3 is provided at the connection between the housing 1 and the cover plate 2. A substrate 4 is provided in the middle between the housing 1 and the cover plate 2. An input interface 5 is provided at one end of the housing 1, and an output interface 6 is provided on the side of the housing 1 away from the input interface 5. The input interface 5 and the output interface 6 are on the same straight line. Resonators 7 are arranged in the middle of the substrate 4. There are seven sets of resonators 7, and the resonators 7 are arranged alternately. The ends of multiple sets of resonators 7 are all provided with... The filter has a ground hole 8. The input interface 5 and the output interface 6 are both connected to the resonators 7 on both sides through the tap structure 9. The housing 1 provides protection and electromagnetic shielding. The housing 1 has a multi-layer structure. The outer layer uses metal to provide shielding. The cover plate 2 acts as a cover. The housing 1 and the cover plate 2 work together to seal and fix the substrate 4. The electromagnetic coupling between multiple sets of resonators 7 forms multiple resonant units to achieve frequency selection. The interdigital structure is compact and suitable for miniaturization design. The input interface 5 and the output interface 6 are used to connect external lines. The ground hole 8 can ensure a good connection between the filter and the system ground.

[0030] The tap structure 9 includes an external portion 10, a transition portion 11, and a connecting portion 12. One side of the external portion 10 is connected to the transition portion 11, and one side of the transition portion 11 is connected to the connecting portion 12. The widths of the external portion 10, the transition portion 11, and the connecting portion 12 decrease sequentially, and the transition portion 11 is inclined. The overall shape of the tap structure 9 is trapezoidal. The tap structure 9 is used to achieve impedance matching between the filter's input and output ports and external circuits (such as transmission lines and antennas). Impedance matching can reduce signal reflection and improve transmission efficiency. By adjusting the position and width of the taps, the equivalent impedance of the input and output ports can be changed. To improve the impedance matching with the external circuit, since the impedances of the external part 10 and the connection part 12 are different, the step connection will result in a large return loss at the port. According to transmission line theory, a transition part 11 can be added between the two to improve the return loss at the port. The smoother the transition, the smaller the return loss at the port. The connection part 12 can be optimized to different widths and lengths according to the specifications, which increases the optimization space. The closer the tap structure 9 is to the ground terminal, the smaller the quality factor Q of the filter. Therefore, when the relative positions of the tap structures 9 are consistent, the trapezoidal tap interdigital filter has a smaller quality factor Q.

[0031] The width of the external portion 10 corresponds to a 50Ω system impedance and is connected to the outside. The higher the proportion of its length in the entire tap, the smaller the quality factor Q. The impedance values ​​between the external portion 10 and the connection portion 12 are different. The external portion 10, the transition portion 11 and the connection portion 12 form the tap structure 9, which improves the performance parameters of the interdigital filter of the same order, especially in terms of return loss. This helps to save costs and avoids the waste of costs due to high-performance materials or special processes.

[0032] The transition section 11 is a progressive trapezoidal shape, and the connecting section 12 is optimized with different widths and lengths according to the specifications. In practical applications, the three parts of the trapezoidal interdigital filter tap can be appropriately optimized according to the specifications to improve the system performance. Compared with the common rectangular tap filter, the trapezoidal tap interdigital filter has advantages in both return loss and out-of-band suppression.

[0033] The passband bandwidth of substrate 4 and resonator 7 is 20-27.5GHz, with a relative bandwidth of 30%, in-band flatness of less than 0.5dB, passband insertion loss of less than 1.2dB, and return loss of greater than 20dB. The substrate 4 is made of RO4003 material and has a cavity depth of 6mm. It is a seventh-order interdigital filter. By reasonably designing the electrode size, selecting the dielectric substrate 4, and optimizing the tap form, excellent filtering performance can be achieved.

[0034] The bottom of the housing 1 has a heat-conducting plate 13, and heat sinks 14 are arranged and connected to the outer wall of the heat-conducting plate 13. The heat-conducting plate 13 plays the role of heat conduction, which can absorb the heat generated when the device is working and release the heat through the heat sink 14, thereby improving the heat dissipation performance of the device. It can effectively reduce the temperature rise of the seventh-order interdigital filter and improve its reliability and stability in high-power applications.

[0035] The implementation principle of this application embodiment is as follows: First, the housing 1 serves as protection and electromagnetic shielding. The housing 1 and the cover plate 2 cooperate to seal and fix the substrate 4. The electromagnetic coupling between multiple sets of resonators 7 forms multiple resonant units, realizing the frequency selection function. The interdigital structure is compact and suitable for miniaturization design. The input interface 5 and the output interface 6 serve to connect external lines. The ground hole 8 can ensure a good connection between the filter and the system ground. Since the impedance of the external part 10 and the connection part 12 is different, the step connection will result in a large return loss at the port. According to transmission line theory, a transition part 11 can be added between the two to improve the return loss at the port. The smoother the transition, the smaller the return loss at the port. The connection part 12 can be optimized to different widths according to the specifications. The length increases the optimization space. The closer the tap structure 9 is to the ground terminal, the smaller the quality factor Q of the filter. Therefore, when the relative positions of the tap structures 9 are consistent, the trapezoidal tap interdigital filter has a smaller quality factor Q. The tap structure 9, composed of the external part 10, the transition part 11 and the connecting part 12, improves the performance parameters of the interdigital filter of the same order, especially in terms of return loss. This helps to save costs and avoids the waste of costs due to high-performance materials or special processes. The heat-conducting plate 13 plays a role in heat conduction, which can absorb the heat generated during the operation of the device and release the heat through the heat sink 14, thereby improving the heat dissipation performance of the device. This can effectively reduce the temperature rise of the seventh-order interdigital filter and improve its reliability and stability in high-power applications.

[0036] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.

Claims

1. A trapezoidal tapped interdigital filter, comprising a housing (1), characterized in that: The top of the housing (1) is bolted to a cover plate (2), the housing (1) and the cover plate (2) are matched, a sealing gasket (3) is provided at the connection between the housing (1) and the cover plate (2), a base plate (4) is provided in the middle between the housing (1) and the cover plate (2), an input interface (5) is provided at one end of the housing (1), an output interface (6) is provided on the side of the housing (1) away from the input interface (5), the input interface (5) and the output interface (6) are on the same straight line, a resonator (7) is arranged in the middle of the base plate (4), there are seven sets of resonators (7), and the resonators (7) are arranged alternately in sequence, and ground holes (8) are provided at the ends of multiple sets of resonators (7), and the input interface (5) and the output interface (6) are connected to the resonators (7) on both sides through a tap structure (9).

2. A trapezoidal tapped interdigital filter according to claim 1, characterized in that: The tap structure (9) includes an outer part (10), a transition part (11) and a connecting part (12). The outer part (10) is connected to the transition part (11) on one side, and the transition part (11) is connected to the connecting part (12) on one side. The widths of the outer part (10), the transition part (11) and the connecting part (12) decrease sequentially, and the transition part (11) is inclined. The overall shape of the tap structure (9) is a trapezoidal structure.

3. A trapezoidal tapped interdigital filter according to claim 2, characterized in that: The width of the external portion (10) corresponds to a 50Ω system impedance and is connected to the outside. The higher its length accounts for a proportion of the entire tap, the smaller the quality factor Q. The impedance values ​​between the external portion (10) and the connection portion (12) are different.

4. A trapezoidal tapped interdigital filter according to claim 3, characterized in that: The transition part (11) is a progressive trapezoidal shape, and the connecting part (12) is specifically optimized to different widths and lengths according to the indicators.

5. A trapezoidal tapped interdigital filter according to claim 1, characterized in that: The passband bandwidth of the substrate (4) and the resonator (7) is 20-27.5GHz, the relative bandwidth is 30%, the in-band flatness is less than 0.5dB, the passband insertion loss is less than 1.2dB, the return loss is greater than 20dB, the substrate (4) is made of RO4003 material, and the cavity depth is 6mm.

6. A trapezoidal tapped interdigital filter according to claim 1, characterized in that: The bottom of the housing (1) has a heat-conducting plate (13), and heat sinks (14) are arranged and connected to the outer wall of the heat-conducting plate (13).

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