Miniaturized dual coaxial cavity filter, control method and application

Abstract

The application belongs to the technical field of filters, and discloses a miniaturized double-coaxial cavity filter, a control method and application, which comprises a metal cavity, a cover plate, supporting medium, a slot-shaped resonant column, a feeder and two SMA-K type joints; the metal cavity is composed of three miniaturized single resonant cavities in cascade, the single resonant cavity is composed of one cavity and two slot-shaped resonant columns with different sizes, the two slot-shaped resonant columns are nested and multiplexed, the wall thickness of the slot-shaped resonant column in the resonant cavity at both ends is 0.6 mm, the wall thickness of the slot-shaped resonant column inside and outside the middle resonant cavity is 1.7 mm, and a three-order miniaturized coaxial filter symmetrical to the middle cavity is formed. The application is provided with a single-column slot structure facilitating multiplexing of multiple resonant columns, multiple resonant columns are loaded by a single cavity, the space structure is more compact, and the cavity utilization rate is improved. The application solves the problem of miniaturization of the all-metal cavity, and the single-cavity miniaturization mode can be used for other transmission line structures.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of filters, and particularly relates to a miniaturized double-coaxial cavity filter, a control method and application. BACKGROUND

[0002] At present, along with the expansion of mobile communication demand, the use amount of communication equipment and infrastructure has increased sharply. Cavity filters have become indispensable radio frequency devices for mobile communication base stations and high-power communication systems due to high Q value, high power capacity and low cost. Cavity filters usually use multiple resonant cavities to realize cascaded coupling, but the inherent characteristics of resonating by relying on the internal cavity structure make the volume of the filter relatively large, and the lower the working frequency, the longer the wavelength, and the larger the cavity volume. Current coaxial cavity miniaturization technologies include (1) loading a capacitor structure, but the circuit structure is complex, and the resonant frequency is reduced at the cost of Q value; (2) using cross-coupling to generate transmission zeros to reduce the filter order, but the topology structure is complex, and the debugging difficulty is increased; (3) multi-mode technology, which reduces the number of resonant cavities, but brings certain insertion loss, etc. Each miniaturization technology has its own limitations, and often needs to be used in combination. Therefore, in the development process of the communication system radio frequency front-end filter circuit towards low loss, small size and light weight, simply and effectively realizing miniaturization and high performance of the cavity filter is still a problem to be solved in the exploration of resonant cavity miniaturization technology.

[0003] The patent "A miniaturized low-frequency cavity filter" (CN 214477826U) designs a miniaturized low-frequency cavity filter, which uses a loaded microwave dielectric block to form a loaded capacitor, so that the cavity filter works at low frequency without increasing the volume. Introducing dielectric is a kind of method, but in the miniaturization of medium and high frequency cavity filters, the dielectric material is limited. Moreover, the tuning screw needs to pass through the dielectric block and insert into the resonant rod, and the connection structure is complex, and the processing and debugging are prone to deviation.

[0004] The document "Wang X, Jang G, Lee B, et al. Compact quad-mode bandpass filter using modified coaxial cavity resonator with improved Q-factor[J]. IEEE Transactions on Microwave Theory and Techniques, 2015, 63(3): 965-975." proposes a new four-mode coaxial cavity composed of four conductive columns in a single cavity, which realizes a new four-mode resonant mode for a bandpass filter and improves the space utilization of a single cavity. However, the size of only two cavities is 43mm*21mm*15.5mm.

[0005] The document "Zhang Z C, Wong S W, Yu X, et al. Compact Quadruple-Mode Wideband Bandpass Filter Using L-Shaped Feed-Line in a Single Cavity [J]. IEEE Microwave and Wireless Components Letters, 2021, 31(10): 1111-1114." designs a four-mode wideband bandpass filter. The single cavity is composed of a pair of symmetrical conductive columns and an L-shaped feed line. The L-shaped feed line not only controls the external coupling, but also is used as a reactance load to reduce the TE mode resonance frequency. To some extent, the volume of the low frequency is reduced, but the adjustment amount introduced is limited, and the volume of the single cavity is only 28mm*28mm*24mm.

[0006] The realization of the small size of the cavity is usually to introduce various complex structures or to use dielectric, and the frequency range and Q value are limited. The research on high-quality factor, low-loss all-metal small-size cavity filter still needs new ideas and new schemes.

[0007] Through the above analysis, the problems and defects of the prior art are that the volume of the existing cavity filter is large, and the lower the working frequency, the longer the wavelength, and the larger the cavity volume. SUMMARY

[0008] In view of the problems existing in the prior art, the present application provides a small-size double coaxial cavity filter, a control method and an application.

[0009] The present application is realized in the following way. A small-size double coaxial cavity filter comprises:

[0010] A metal cavity, a cover plate, a support medium, a slot-shaped resonant column, a feed line, and two SMA-K connectors; the metal cavity is composed of three small single resonant cavities in cascade, and the cover plate is located at the top of the metal cavity, so that the metal cavity forms a closed space and reduces radiation loss; wherein the single resonant cavity is composed of a cavity and two slot-shaped resonant columns with different sizes, and the two slot-shaped resonant columns are nested and multiplexed; the support medium is located between the inner and outer resonant columns and plays a wrapping and supporting role for the inner resonant column. The input feed line is fed into the outer slot-shaped resonant column in the first resonant cavity, and the output feed line is connected to the outer slot-shaped resonant column in the third resonant cavity to output energy; the SMA-K tap contains input and output feed lines and is located at the input and output ends of the metal cavity, and is connected with an external circuit. The metal cavity is composed of three small single resonant cavities in cascade, and the single resonant cavity is composed of a cavity and two slot-shaped resonant columns with different sizes, and the two slot-shaped resonant columns are nested and multiplexed.

[0011] Further, in the single cavity, the nested double-conductor post is located in the center of the cavity, and the whole cavity is symmetrical with the slot-shaped post.

[0012] Further, the thickness of the bottom of the two slot-shaped posts is 2mm, the side wall of the nested post is separated by 0.6mm, and the bottom is separated by 3mm.

[0013] Further, the Q value is 2057.

[0014] Further, in the single resonant cavity, a support medium is injected between the two slot-shaped posts, which can wrap the bottom of the inner slot-shaped post, so that the structure of the two nested posts is stable.

[0015] Further, the support medium is a Teflon (tm) resin medium material with a relative dielectric constant of 2.1, and the dielectric constant of the medium material needs to be close to or higher than the original air medium, which has good electrical insulation and reduces the influence on the resonant circuit, and is only used as a support medium.

[0016] Further, in the design of a three-order coaxial filter based on the nested structure, the slot-shaped posts in the resonant cavities at both ends adopt the initial size of the single cavity, the wall thickness of the outer slot-shaped post of the middle resonant cavity is 1.7mm, and the wall thickness of the inner resonant post is still 0.6mm, forming a three-order miniaturized coaxial filter symmetrical to the middle cavity.

[0017] Further, the tap feeds the outer slot-shaped post in the adjacent cavity, and the tap probe is higher than the bottom of the inner slot-shaped post.

[0018] Further, the SMA-K type joint is placed on both sides of the input and output ends of the filter, and the cavity filter is connected to the external circuit and matched with the external circuit through the SMA-K type joint and the 50Ω characteristic impedance transmission line.

[0019] Another object of the present application is to provide a control method of a miniaturized double-coaxial cavity filter, which comprises:

[0020] Step one, nested multiplexing single cavity design.

[0021] The coaxial transmission line is adopted / 4 coaxial transmission line, wherein The wavelength is corresponding to the working frequency; the slot resonant column has electromagnetic field distribution of general coaxial transmission line. The slot depth and wall thickness affect the working frequency and quality factor Q of single resonant cavity. When multiplexing one resonant column, the resonant frequency decreases, but the Q value decreases and the insertion loss value increases when the single cavity structure size is unchanged. Therefore, the single cavity size parameters need to be determined according to the center frequency and appropriate Q value.

[0022] Step two, determination of the coupling coefficient between the multiplexed single cavities.

[0023] In the design of a three-order coaxial cavity filter, the inter-cavity coupling coefficient matrix is calculated by filter synthesis software according to the design index, and the theoretical value of the inter-cavity coupling coefficient is determined as m 12 =0.0226, m 23 =0.017. In actual electromagnetic simulation, the two eigenfrequencies of the cavity coupled resonator can be extracted by using the eigenmode solution mode of HFSS. The actual inter-cavity coupling coefficient is calculated, the inter-cavity coupling distance is adjusted to an appropriate position with reference to the theoretical value.

[0024] Another object of the present application is to provide a communication device provided with the miniaturized double coaxial cavity filter.

[0025] In combination with the above technical solutions and the technical problems solved, the technical solutions of the present application have the following advantages and positive effects:

[0026] First, in view of the technical problems existing in the prior art and the difficulty in solving the problems, the technical solutions of the present application are closely combined with the results and data obtained during the research and development process, and the technical problems solved by the technical solutions are analyzed in detail and deeply. Some creative technical effects brought about after solving the problems are described as follows:

[0027] The present application is provided with a single-column slot structure convenient for multiplexing a plurality of resonant columns, and a plurality of resonant columns are loaded in a single cavity to make the space structure more compact and improve the utilization rate of the cavity. The present application solves the problem of miniaturization of the all-metal cavity filter, and this single-cavity miniaturization method can be used for other transmission line structures.

[0028] The filter in the present application has a return loss S 11 of less than -26dB and an insertion loss S12 of greater than -0.2dB within 1.15-1.54GHz.

[0029] The filter in the present application realizes a transmission zero point at 2.13GHz, improving the passband selectivity.

[0030] ​The cavity filter in the application has excellent structural characteristics, simple and compact structure, and overall size is only , and miniaturization is realized.

[0031] Secondly, the technical scheme is regarded as a whole or from the product point of view, the technical effects and advantages of the technical scheme to be protected by the application are described as follows:

[0032] The application realizes low loss, good passband selectivity, and quality factor guarantee, and further realizes miniaturization of the cavity filter to meet the requirements of lightness, compactness and integrability of the radio frequency element of the communication network.

[0033] In the design of the miniaturized coaxial cavity filter, the technical effects and advantages of the application are as follows: first, compared with the traditional resonant cavity cascade type cavity arrangement, the resonant column unit is multiplexed in a nested manner to form a new miniaturized resonant single cavity, the resonant frequency is reduced, and the size of the low-frequency cavity filter is reduced. Second, the resonant column unit is designed as a slot type, which is convenient for the use of the nested structure and the realization of the miniaturized single cavity. The wall thickness and slot depth of the slot type resonant column greatly affect the working frequency and Q value of the single cavity. The smaller the wall thickness, the greater the resonant column height, the lower the frequency, the greater the Q value, and the smaller the insertion loss. However, due to the limitation of machining precision, the minimum wall thickness is 0.6mm. Third, the output coaxial line structure and the adjacent resonant cavity based on the nested multiplexing structure produce cross coupling, which produces transmission zeros in the out-of-band, greatly improving the out-of-band suppression degree. Third, as the creative auxiliary evidence of the claims of the application, it is also reflected in the following important aspects:

[0034] (1) The expected income and commercial value of the technical scheme of the application after transformation are:

[0035] Two resonant units are multiplexed in a nested manner, so that the low-frequency single resonant cavity structure is compact, and the Q value reaches 2000. Compared with the method of increasing the electrical size of the cavity filter by loading other complex circuit structures, the structure is simple, easy to assemble, and low in cost on the basis of maintaining good filtering performance.

[0036] (2) The technical scheme of the application solves the technical problems that people have been eager to solve but have failed to succeed:

[0037] The nested mode often appears in the design of planar filters such as microstrip line, and the nesting of resonant loops. The present application uses the nested mode between resonant units for miniaturization of three-dimensional metal cavity filters, and uses groove-type resonant columns in combination with the nested multiplexing mode. Compared with dielectric cavity filters, the high Q value of metal cavity filters is retained, reaching about 2000. Compared with single-cavity miniaturization technologies such as loading capacitors and multi-mode technology, the structure is simple and the insertion loss is low. For the problem that it is difficult to use cross-coupling to generate transmission zeros for straight-line cavity filters, the special double-resonant-column nested multiplexing mode generates cross-coupling with the output feed line, generating a transmission zero at 2.13 GHz outside the band, and improving the out-of-band selectivity. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a top view schematic diagram of a miniaturized double-coaxial cavity filter provided by an embodiment of the present application.

[0039] In the figure, R1, R2, and R3 are miniaturized resonant single cavities using the nested mode.

[0040] Figure 2 is a schematic diagram of resonant column multiplexing structure in a single cavity provided by an embodiment of the present application; in groove-type resonant columns 1 and 2, d=3mm is the nesting interval, and n_h1=2mm is the thickness of the bottom of the groove-type resonant column.

[0041] Figure 3 is a schematic diagram of a support medium position provided by an embodiment of the present application; 3 is a dielectric ring column.

[0042] Figure 4 is a schematic diagram of a support medium structure provided by an embodiment of the present application.

[0043] Figure 5 is a cross-sectional view of a support medium provided by an embodiment of the present application; the height of the medium is 4.5mm.

[0044] Figure 6 is an S 11 , S 12 curve diagram of a miniaturized double-coaxial cavity filter provided by an embodiment of the present application; in the passband of 1.15-1.54GHz, the return loss S 11 is less than -26dB, and the insertion loss S 12 is greater than -0.2dB. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0046] I. Embodiment Explanation. In order for those skilled in the art to fully understand how the present application is specifically implemented, this part is an embodiment explanation of the technical solution of the claims.

[0047] As shown in Figures 1 to 6 The miniaturized dual-coaxial cavity filter provided by the embodiment of the present application is composed of a metal cavity formed by cascading three miniaturized single cavities, a cover plate, a support medium, a slot-shaped resonant column, a feed line, and two SMA-K connectors. The metal cavity is formed by cascading three miniaturized single cavities, and the cover plate is located at the top of the metal cavity, so that the metal cavity forms a closed space and reduces radiation loss. The single cavity is composed of a cavity and two slot-shaped resonant columns with different sizes, and the two slot-shaped resonant columns are nested and multiplexed. The support medium is located between the inner and outer resonant columns and plays a wrapping and supporting role on the inner resonant column. The input feed line is fed into the outer slot-shaped resonant column in the first resonant cavity, and the output feed line is connected to the outer slot-shaped resonant column in the third resonant cavity to output energy. The SMA-K tap contains input and output feed lines and is connected to the input and output ends on both sides of the metal cavity.

[0048] The single cavity is composed of a cavity and two resonant columns with different sizes, and the two resonant columns are nested and multiplexed.

[0049] The single metal column has a specific slot depth and wall thickness according to the frequency of the resonant cavity, which facilitates the insertion of the inner resonant column with the same structure. The thickness of the slot bottom of the inner and outer resonant columns is 2 mm.

[0050] The wall thickness of the inner resonant column at both ends is 0.6 mm, and the wall thickness of the outer resonant column in the middle is 1.7 mm, forming a three-order miniaturized coaxial filter symmetrically with the middle cavity.

[0051] In the single cavity, the support medium that can wrap the bottom of the inner resonant column is injected between the two metal ring columns, making the structure stable.

[0052] The support medium is Teflon (tm) with a relative dielectric constant of 2.1.

[0053] The tap probe is fed into the outer resonant column in the adjacent cavity, and the tap height is higher than the bottom of the inner resonant column.

[0054] The electric field changes back and forth in the gap between the inner and outer resonant columns, and the electric field is strongest at the intersection of the top of the two resonant columns.

[0055] 1. The present application solves the problem of miniaturization of all-metal cavities, and this single-cavity miniaturization method can be used for other transmission line structures.

[0056] 2. The resonant frequency of the filter is 1.41 GHz, and the return loss S 11 is less than -26 dB, and the insertion loss S12 greater than -0.2 dB.

[0057] 3. A transmission zero point is achieved at 2.13 GHz, improving the passband selectivity.

[0058] 4. The cavity filter has excellent structural characteristics and simple and compact structure.

[0059] 5. The overall size of the filter is only .

[0060] 6. Miniaturization is achieved.

[0061] II. Application Examples. In order to prove the creativity and technical value of the technical solutions of the present application, this part is an application example of the technical solutions of the claims on specific products or related technologies.

[0062] The resonant unit multiplexing structure in the embodiment of the present application can be applied to other transmission line structures, and the miniaturized filter can be applied to communication equipment in the same frequency band.

[0063] In the specific product design, the groove depth of the resonant column and the height of the medium are adjusted according to the machining precision, so that the cutter can be cut. The center frequency is 1.5 GHz, the filter has S 11 <-40dB, S 21 >-0.2dB in the passband range of 1.42GHz-1.72GHz. The out-of-band suppression at 2.3GHz is more than 35dB, the standing wave ratio is less than 1.5, the out-of-band transmission zero point is located at 2.52GHz, and the design index requirements are met.

[0064] In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0065] III. Evidence of the effects of the embodiments. The embodiments of the present application have achieved some positive effects in the research and development or use process, and indeed have great advantages compared with the prior art. The following content is described in combination with the data and graphs of the test process.

[0066] Compared with other small-sized coaxial cavity filters in the medium and low frequency band, the electrical size comparison is as follows:

[0067] References f 0 (GHz) ​ Cavity Q value Electrical dimensions [1] 0.8859 4463 0.177λg*0.177λg*0.112λg [2] 2.45 - 0.103λg*0.898λg*0.221λg [3] 2.55 1700 0.366λg*0.179λg*0.132λg [4] 2.2 1820 0.27λg*0.27λg*0.16λg [5] 3.5 - 0.198λg*0.35λg*0.17λg [6] 1.8 - 0.156λg*0.156λg*0.072λg [7] 3.5 - 0.198λg*0.175λg*0.151λg Sectional filter 1.5 1962 0.075λg*0.147λg*0.094λg

[0068] [1] Yang Yongxia, Liu Fangfang, Guo Liang. Study and Design of bandpass filter for Coaxial cavity [J]. Proceedings of Xi'an Polytechnic University, 2015,35(07):521-526. DOI:10.16185 / j.jxatu.edu.

[0069] [2] Shi Zhixiong, Li Simin, Qin Mi, Ye Jincai, Wang Guofu. Study design of 2.45 GHz [J]. Piezoelectric and acoustic light,2021,43 (02): 161-164.

[0070] [3] Z. -C. Zhang, S. -W. Wong, X. Yu, B. Zhao, D. Wang and R. Chen, "Compact Quadruple-Mode Wideband Bandpass Filter Using L-Shaped Feed-Line in a Single Cavity," in IEEE Microwave and Wireless Components Letters, vol. 31, no. 10, pp. 1111-1114, Oct. 2021, doi: 10.1109 / LMWC.2021.3107952.

[0071] [4] Lei Guang, Wang Peizhang, Xu Zhou. Design of S-band capacitive loading coaxial cavity filter [J]. Military communication technology, 2010, 3.

[0072] [5] Li S, Wang X, Li Y, et al. Design of compact coaxial cavity bandpass filter with high selectivity[C] / / 2019IEEE MTT-S International Microwave Biomedical Conference (IMBioC). IEEE, 2019, 1: 1-4.

[0073] [6] Zhang Z C, Yang J P, Li Q Y, et al. Design of miniaturized bandpass filter using modified coaxial cavity resonator[C] / / 2019International Conference on Microwave and Millimeter Wave Technology (ICMMT). IEEE, 2019: 1-3.

[0074] [7] Y. Chen and K. -L. Wu, "An All-metal Capacitive Coupling Structurefor Coaxial Cavity Filters," 2020 IEEE / MTT-S International Microwave Symposium (IMS), 2020, pp. 583-586, doi:10.1109 / IMS30576.2020.9223932.

[0075] From the table, it can be seen that the small size advantage of the small size coaxial cavity filter based on the nested multiplexing mode.

[0076] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement within the technical range disclosed by the present application, which is within the spirit and principle of the present application, should be covered within the protection scope of the present application.

Claims

1. A miniaturized dual coaxial cavity filter, characterized in that, The small-sized double coaxial cavity filter is provided with: The metal cavity, the cover plate, the support medium, the slot-shaped resonant column, the feeder, and the two SMA-K connectors; the metal cavity is composed of three small-sized single resonant cavities in cascade, and the cover plate is located at the top of the metal cavity; wherein the single resonant cavity is composed of a cavity and slot-shaped inner and outer resonant columns with different sizes, the two slot-shaped resonant columns are nested and multiplexed, the support medium is located between the inner and outer resonant columns, and plays a wrapping and supporting role on the inner resonant column; the input feeder is fed into the outer slot-shaped resonant column in the first resonant cavity, and the output feeder is connected to the outer slot-shaped resonant column in the third resonant cavity to output energy; the SMA-K tap includes input and output feeders, and is located at the input and output ends of the metal cavity and connected with external circuits.

2. The miniaturized dual coaxial cavity filter of claim 1, wherein, The double conductor columns nested and multiplexed in the single cavity are located at the center of the cavity, and the entire cavity is symmetrical to the slot-shaped ring column; The initial dimensions at a center frequency of 1.45 GHz are as follows: the wall thickness of the outer slot-shaped resonant column is 1.2 mm, the slot depth is 17 mm, the wall thickness of the inner slot-shaped resonant column is 0.6 mm, and the slot depth is 14 mm.

3. The miniaturized dual coaxial cavity filter of claim 2, wherein, The thicknesses of the bottoms of the two slot-shaped resonant columns are both 2 mm, the side wall interval of the nested resonant columns is 0.6 mm, and the bottom interval is 3 mm.

4. The miniaturized dual coaxial cavity filter of claim 2, wherein, In the single resonant cavity, the support medium is injected between the two slot-shaped resonant columns to wrap the bottom of the inner slot-shaped resonant column.

5. The miniaturized dual coaxial cavity filter of claim 1, wherein, The support medium is a Teflon resin medium material with a relative dielectric constant of 2.

1.

6. The miniaturized dual coaxial cavity filter of claim 1, wherein, The slot-shaped resonant columns in the resonant cavities at both ends adopt the initial dimensions of the single cavity, the wall thickness of the outer slot-shaped resonant column in the middle resonant cavity is 1.7 mm, and the wall thickness of the inner resonant column is still 0.6 mm, thereby forming a three-order small-sized coaxial filter symmetrical to the middle cavity.

7. The miniaturized dual coaxial cavity filter of claim 1, wherein, The feeder in the tap is fed into the outer slot-shaped resonant column in the adjacent cavity, is short-circuited with the inner wall of the outer resonant column, and the height of the tap probe is higher than the bottom of the inner slot-shaped resonant column.

8. The miniaturized dual coaxial cavity filter of claim 1, wherein, The SMA-K connector is located at the two sides of the input and output ends of the filter, and the cavity filter is connected to the external circuit and matched with the external circuit through the SMA-K connector and the 50Ω characteristic impedance transmission line.

9. A control method of the miniaturized dual coaxial cavity filter according to any one of claims 1 to 8, characterized by, The control method of the small-sized double coaxial cavity filter comprises: Step one, nested and multiplexed single cavity design Using λ g / 4 coaxial transmission line, slot resonant column has electromagnetic field distribution of general coaxial transmission line; its slot depth and wall thickness affect the working frequency and quality factor Q of single resonant cavity; when the single cavity structure size is unchanged, the resonant frequency decreases, but the Q value decreases and the insertion loss value increases with each multiplexing resonant column; therefore, the single cavity size parameters need to be determined according to the center frequency and appropriate Q value, wherein Step two, determination of the coupling coefficient between the multiplexed single cavities g The wavelength is the wavelength of the corresponding working frequency; The communication device is provided with the small-sized double coaxial cavity filter according to any one of claims 1 to 8. In the design of the third-order coaxial cavity filter, the cavity coupling coefficient matrix is calculated according to the design index by using filter synthesis software, and the theoretical value of the cavity coupling coefficient is determined as m 12 =0.0226, m 23 =0.017; in actual electromagnetic simulation, the actual cavity coupling coefficient is calculated according to the double-mode extraction method , the cavity coupling distance is adjusted to the appropriate position according to the theoretical value, wherein are the two eigenfrequencies of the resonator after the cavity coupling.

10. A communication device, characterized by ​

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