Integrated adjustable filter

Abstract

The invention relates to the technical field of radio frequency microwaves, in particular to an integrated adjustable filter which comprises an adjustable filter body, an input strip line, an output strip line, a coupling strip line set and a YIG thin film structure set are arranged in the adjustable filter body, and the input strip line can be in signal transmission with the output strip line through the coupling strip line set and the YIG thin film structure set. Wherein the adjustable filter body is also internally provided with a plurality of layers of green ceramic medium, the plurality of layers of green ceramic medium are laminated and sintered to form a coupling cavity of the adjustable filter body, a metal circuit image can be printed on the green ceramic medium, and a resonant cavity for placing the YIG film structure group can be dug on the green ceramic medium. By arranging each functional part on the green ceramic medium and then utilizing the LTCC technology, the filter can be integrated, the assembly is simpler, additional strip line processing and the like are not needed, the green ceramic medium can be directly slotted, the fixation and position control of the YIG film structure are more accurate, and subsequent adjustment is not needed.

Description

Technical Field

[0001] The invention relates to the field of radio frequency microwave technology, and in particular to an integrated adjustable filter. Background Art

[0002] Yttrium iron garnet (YIG) is a microwave gyromagnetic material that has both insulating and gyromagnetic properties. By changing the bias magnetic field applied to the YIG material, the gyromagnetic tensor in the YIG material can be changed within an ultra-wideband frequency band, thereby affecting the electromagnetic field characteristics in the film. Therefore, the YIG material has an ultra-wideband magnetic tuning characteristic. The resonator made of YIG material can change its resonant frequency by adjusting the bias magnetic field on the YIG material. The resonator-based filter can also use the characteristics of the YIG material to design and manufacture devices with adjustable center frequencies.

[0003] YIG tuned filter (YTF) is a tunable device based on YIG gyromagnetic material, consisting of a YIG resonant circuit and a magnetic circuit. It is characterized by narrow bandwidth, high out-of-band suppression, and electrical tunability. Its working principle is that the resonant circuit composed of YIG material generates a resonant frequency under the excitation of an external magnetic field, thereby realizing the filtering function of the frequency point, and the resonant frequency of the resonator is changed by changing the magnetic field strength to achieve the tuning function.

[0004] After a lot of research work, foreign countries have developed a series of products that are widely used in military electronic equipment (electronic warfare reconnaissance reception, electronic countermeasures and electronic countermeasures) and other systems, and their YTF technology has also reached a very high level.

[0005] At present, the resonant circuit structure of YTF is mainly based on YIG ball resonators. For example, the Chinese patent with the announcement number CN108767412B discloses an ultra-wideband YIG electrically tunable filter coupled resonant structure based on LTCC. The coupling between the resonant structures is achieved through a precision-machined coupling ring structure. This structure has high requirements on machining accuracy. After assembly, the position and crystal orientation of the YIG ball need to be further adjusted, which makes the manufacturing process complicated. Summary of the invention

[0006] In view of the above problems, the present invention provides an integrated adjustable filter.

[0007] The adopted technical solution is an integrated tunable filter, including a tunable filter body, wherein the tunable filter body is provided with an input strip line, an output strip line, a coupling strip line group and a YIG thin film structure group, wherein the input strip line can transmit signals with the output strip line through the coupling strip line group and the YIG thin film structure group, wherein the tunable filter body is also provided with a multi-layer raw ceramic sheet medium, and the multi-layer raw ceramic sheet medium is stacked and sintered to form a coupling cavity of the tunable filter body, a metal circuit image can be printed on the raw ceramic sheet medium, and a resonant cavity for placing the YIG thin film structure group can be dug out on the raw ceramic sheet medium.

[0008] Optionally, five layers of raw ceramic medium are arranged in the tunable filter body, and the five layers of raw ceramic medium are, from top to bottom, a first layer of raw ceramic medium, a second layer of raw ceramic medium, a third layer of raw ceramic medium, a fourth layer of raw ceramic medium and a fifth layer of raw ceramic medium;

[0009] The first layer of green ceramic medium and the fourth layer of green ceramic medium are green ceramic medium without metal circuit patterns;

[0010] The second layer of raw ceramic sheet medium and the fifth layer of raw ceramic sheet medium are raw ceramic sheet medium printed with metal circuit patterns;

[0011] The third layer of raw ceramic sheet medium is a raw ceramic sheet medium with perforations, and the perforations are used to place the YIG thin film structure group.

[0012] Optionally, an input port and an output port are provided on the first layer of raw ceramic sheet medium, and the input port and the output port are respectively located on two sides of the first layer of raw ceramic sheet medium;

[0013] The metal circuit image printed on the second layer of raw ceramic sheet medium is an input strip line, an output strip line and a first coupling strip line group, and one end of the input strip line is connected to the input port through a metal through hole arranged between the five layers of raw ceramic sheet medium, one end of the output strip line is connected to the output port through a metal through hole arranged between the five layers of raw ceramic sheet medium, and the first coupling strip line group is located between the input strip line and the output strip line;

[0014] The metal circuit image printed on the fifth layer of green ceramic sheet medium is a second coupling strip line group.

[0015] Optionally, the input port and the output port are located on the upper surface of the first layer of green ceramic sheet medium;

[0016] The input strip line, the output strip line and the first coupling strip line group are located on the upper surface of the second layer of raw ceramic sheet medium;

[0017] The second coupling strip line group is located on the upper surface of the fifth green ceramic sheet medium.

[0018] Optionally, four through-holes are provided on the third layer of raw ceramic sheet medium, and the YIG film structure group includes four YIG film structures, which are respectively arranged in the four through-holes to form an input resonator, a second resonator, a third resonator and an output resonator in the order of signal transmission.

[0019] Optionally, the first coupling strip line group includes a first coupling strip line, and the second coupling strip line group includes a second coupling strip line and a third coupling strip line.

[0020] Optionally, the input strip line is located above the input resonator, and the terminal is grounded, and the downward projection of the input strip line can fall on the input resonator;

[0021] The output strip line is located above the output resonator, and the terminal is grounded, and the downward projection of the output strip line can fall on the output resonator;

[0022] The second coupling strip line is located below the input resonator and the second resonator, and an upward projection of the second coupling strip line can fall on the input resonator and the second resonator;

[0023] The third coupling strip line is located below the third resonator and the output resonator, and the upward projection of the second coupling strip line can fall on the third resonator and the output resonator;

[0024] The first coupling strip line is located above the second resonator and the third resonator, and a downward projection of the first coupling strip line can fall on the second resonator and the third resonator.

[0025] Optionally, the input strip line and the second coupling strip line are arranged to cross each other, and the angle between them is 45° and 90°;

[0026] The output strip line and the third coupling strip line are arranged to cross each other, and the included angle is 45° to 90°;

[0027] Two ends of the first coupling strip line are respectively arranged to cross the second coupling strip line and the third coupling strip line, and the included angle is 45° to 90°.

[0028] Optionally, the spacing between the input strip line, the output strip line, the first coupling strip line and the four YIG thin film structures is adjusted by the thickness of the second layer of raw ceramic medium;

[0029] The distances between the second coupling strip line, the third coupling strip line and the four YIG thin film structures are adjusted by the thickness of the fourth green ceramic sheet medium.

[0030] Optionally, the YIG thin film structure includes a gadolinium gallium garnet substrate and a YIG thin film covering the gadolinium gallium garnet substrate, and the YIG thin film structure is manufactured using liquid phase epitaxy technology and has a rectangular parallelepiped shape.

[0031] The beneficial effects of the present invention include at least one of the following:

[0032] 1. By placing various functional components on the raw ceramic medium and then using the LTCC process, the filter can be made into an integrated unit, and the assembly is also simpler without the need for additional processing of strip lines.

[0033] 2. Grooves can be made directly on the raw ceramic medium, which makes the fixation and position control of the YIG film structure more precise and does not require subsequent adjustments.

[0034] 3. The performance of the filter design is closely related to the coupling between resonators and the coupling between input and output and resonators. Therefore, the distance between the input and output strip lines and the coupling strip lines and the YIG resonator needs to be precisely controlled. Since the LTCC process has high flexibility in the design of the thickness of the raw ceramic strip, there are many optional thicknesses, and the thinnest can be about 5 microns. Therefore, compared with the traditional YIG filter design that requires precision processing and precision assembly to achieve, the required coupling can be achieved more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of an integrated adjustable filter;

[0036] Figure 2 It is a schematic diagram of the hierarchical structure of an integrated adjustable filter;

[0037] Figure 3 It is a schematic diagram of the internal structure of an integrated adjustable filter;

[0038] Figure 4 It is a schematic diagram of the YIG film structure;

[0039] Figure 5 It is a schematic diagram of the filter input and output port structure;

[0040] Figure 6 This is the simulation result diagram of the integrated adjustable bandpass filter.

[0041] The reference numerals are:

[0042] 1 is a first layer of raw ceramic medium, 2 is a first additional raw ceramic medium, 3 is a second additional raw ceramic medium, 4 is a second layer of raw ceramic medium, 5 is a third additional raw ceramic medium, 6 is a third layer of raw ceramic medium, 7 is a fourth layer of raw ceramic medium, 8 is a fifth layer of raw ceramic medium, 9 is a fourth additional raw ceramic medium, 11 is an input strip line, 12 is an output strip line, 13 is a first coupling strip line, 14 is a second coupling strip line, 15 is a third coupling strip line, 16 is a YIG thin film structure, 17 is a metal through hole, 18 is an input port, 19 is an output port, 20 is a gadolinium gallium garnet substrate, 21 is a YIG thin film, 23 is an adjustable filter body, 24 is an input test terminal, and 25 is an output test terminal. DETAILED DESCRIPTION

[0043] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0044] It should be noted that the illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0045] An integrated tunable filter comprises a tunable filter body 23, wherein the tunable filter body 23 is provided with an input stripline 11, an output stripline 12, a coupling stripline group and a YIG thin film structure group, wherein the input stripline 11 can transmit signals with the output stripline 12 through the coupling stripline group and the YIG thin film structure group, wherein the tunable filter body 23 is further provided with a multi-layer raw ceramic sheet medium, and the multi-layer raw ceramic sheet medium is stacked and sintered to form a coupling cavity of the tunable filter body 23, a metal circuit image can be printed on the raw ceramic sheet medium, and a resonant cavity for placing the YIG thin film structure group can be dug out on the raw ceramic sheet medium.

[0046] The purpose of this design is to make the filter integrated by placing various functional components on the raw ceramic medium and then using the LTCC process, which makes assembly simpler and does not require additional processing of strip lines, etc. Grooving can be directly performed on the raw ceramic medium, which makes the fixation and position control of the YIG film structure more precise and does not require subsequent adjustments.

[0047] This embodiment provides a five-layer raw ceramic medium structure, wherein five layers of raw ceramic medium are arranged in the tunable filter body 23, and the five layers of raw ceramic medium are, from top to bottom, a first layer of raw ceramic medium 1, a second layer of raw ceramic medium 4, a third layer of raw ceramic medium 6, a fourth layer of raw ceramic medium 7 and a fifth layer of raw ceramic medium 8;

[0048] The first layer of green ceramic medium 1 and the fourth layer of green ceramic medium 7 are green ceramic mediums without metal circuit patterns;

[0049] The second layer of green ceramic medium 4 and the fifth layer of green ceramic medium 8 are green ceramic medium printed with metal circuit patterns;

[0050] The third layer of green ceramic sheet medium 6 is a green ceramic sheet medium with holes, and the holes are used to place the YIG thin film structure group.

[0051] Meanwhile, the first layer of raw ceramic sheet medium 1 is provided with an input port 18 and an output port 19, and the input port 18 and the output port 19 are respectively located on both sides of the first layer of raw ceramic sheet medium 1;

[0052] The metal circuit image printed on the second layer of raw ceramic sheet medium 4 is an input strip line 11, an output strip line 12 and a first coupling strip line group, and one end of the input strip line 11 is connected to the input port 18 through a metal through hole 17 arranged between the five layers of raw ceramic sheet medium, and one end of the output strip line 12 is connected to the output port 19 through a metal through hole 17 arranged between the five layers of raw ceramic sheet medium, and the first coupling strip line group is located between the input strip line 11 and the output strip line 12;

[0053] The metal circuit image printed on the fifth layer of green ceramic sheet medium 8 is a second coupling strip line group.

[0054] like Figure 1 As shown, in a specific implementation, in order to control the performance of the entire filter, an input test terminal 24 and an output test terminal 25 can usually be set on both sides of the filter for connecting to an external circuit, and the input test terminal 24 is connected to the input port 18, and the output test terminal 25 is connected to the output port 19.

[0055] Furthermore, in this embodiment, if Figure 3 and Figure 5 As shown, the input port 18 and the output port 19 are located on the upper surface of the first layer of raw ceramic medium 1;

[0056] The input strip line 11, the output strip line 12 and the first coupling strip line group are located on the upper surface of the second layer of raw ceramic medium 4;

[0057] The second coupling strip line group is located on the upper surface of the fifth green ceramic sheet medium 8 .

[0058] At the same time, four through-holes are opened on the third layer of raw ceramic medium 6, and the YIG film structure group includes four YIG film structures 16, which are respectively arranged in the four through-holes to form an input resonator, a second resonator, a third resonator and an output resonator in the order of signal transmission.

[0059] Furthermore, the first coupling strip line group includes a first coupling strip line 13 , and the second coupling strip line group includes a second coupling strip line 14 and a third coupling strip line 15 .

[0060] At the same time, the input strip line 11 is located above the input resonator, and the terminal is grounded, and the downward projection of the input strip line 11 can fall on the input resonator;

[0061] The output strip line 12 is located above the output resonator, and the terminal is grounded, and the downward projection of the output strip line 12 can fall on the output resonator;

[0062] The second coupling strip line 14 is located below the input resonator and the second resonator, and the upward projection of the second coupling strip line 14 can fall on the input resonator and the second resonator;

[0063] The third coupling strip line 15 is located below the third resonator and the output resonator, and the upward projection of the second coupling strip line 14 can fall on the third resonator and the output resonator;

[0064] The first coupling strip line 13 is located above the second resonator and the third resonator, and the downward projection of the first coupling strip line 13 can fall on the second resonator and the third resonator.

[0065] It should be pointed out that the working principle of the entire tunable filter is that the input signal is input from the input port, transmitted to the input stripline through the metallized through-hole provided on the metal green ceramic sheet medium, and then coupled to the input resonator through the input stripline, and then coupled to the second coupling stripline through the input resonator, and transmitted along the second coupling stripline, and coupled to the second resonator at the same time, after being processed by the second resonator, coupled to the first coupling stripline, and transmitted along the first coupling stripline to couple to the third resonator, after being processed by the third resonator, coupled to the third coupling stripline, and then coupled to the output resonator through the third coupling stripline, and coupled to the output stripline through the output resonator, and finally transmitted to the output port through the metallized through-hole provided on the metal green ceramic sheet medium.

[0066] It should also be pointed out that the above principle description is mainly for four resonators and is not intended to be limiting. Those skilled in the art can set more resonators and coupling strip lines according to actual conditions, and the principle remains the same.

[0067] In this embodiment, the input strip line 11 and the second coupling strip line 14 are arranged to cross each other, and the angle between them is 45° and 90°;

[0068] The output strip line 12 and the third coupling strip line 15 are arranged to cross each other, and the included angle is 45° to 90°;

[0069] Two ends of the first coupling strip line 13 are respectively arranged to cross the second coupling strip line 14 and the third coupling strip line 15 , and the included angle is 45° to 90°.

[0070] It should be pointed out that, generally speaking, a 90° angle is the best.

[0071] In this embodiment, the spacing between the input strip line 11, the output strip line 12, the first coupling strip line 13 and the four YIG thin film structures 16 is adjusted by the thickness of the second raw ceramic sheet medium 4;

[0072] The distances between the second coupling strip line 14 , the third coupling strip line 15 and the four YIG thin film structures 16 are adjusted by the thickness of the fourth green ceramic sheet medium 7 .

[0073] The purpose of this design is that the distance between the input strip line, output strip line and coupling strip line and the YIG thin film structure can be adjusted by the thickness of the green porcelain tape medium; the specific gap size and strip line width are obtained according to the bandwidth design requirements and simulation of the filter; the thicker the thickness, the farther the distance between the strip line and the YIG film, the weaker the coupling, and the smaller the bandwidth; the thinner the thickness, the closer the distance between the strip line and the YIG film, the stronger the coupling, and the wider the bandwidth.

[0074] Based on this, Figure 2 As shown, a nine-layer raw ceramic medium structure tunable filter is provided. On the basis of the five-layer raw ceramic medium structure, a first additional raw ceramic medium 2 and a second additional raw ceramic medium 3 are additionally arranged under the first layer of raw ceramic medium to increase the distance between the first layer of raw ceramic medium and the second layer of raw ceramic medium, and a third additional raw ceramic medium 5 is added to increase the thickness between the second layer of raw ceramic medium and the third layer of raw ceramic medium. Finally, a fourth additional raw ceramic medium is added under the fifth layer of raw ceramic medium for protection.

[0075] According to the structure given in this embodiment, the stacking order of the nine-layer structure according to the LTCC process is as follows: the fifth layer of raw ceramic medium with a coupling strip line is stacked on the fourth additional raw ceramic medium, and then the fourth layer of raw ceramic medium is stacked, and then the third layer of raw ceramic medium with a square hole is stacked, and the YIG thin film structure is placed in the square hole, and then the third additional raw ceramic medium is stacked, and then the second layer of raw ceramic medium with input and output strip lines and coupling strip lines is stacked, and then the second additional raw ceramic medium, the first additional raw ceramic medium and the first layer of raw ceramic medium are stacked according to the thickness required by the design, and the first layer of raw ceramic medium has input and output ports on top.

[0076] At the same time, when the input signal is input from the input strip line 11, if the input signal frequency is the same as the ferromagnetic resonance frequency of the YIG film, the input YIG film resonator is excited to generate a magnetic field and couple with the second coupling strip line 14. The second coupling strip line 14 couples microwave energy to the second YIG film resonator. After the second resonator is excited, it couples the microwave energy to the first coupling strip line 13, and then through the strip line-film excitation coupling mode, the energy is finally transmitted through the output strip line 12. When the input signal frequency is different from the ferromagnetic resonance frequency of the YIG film, the YIG film is not excited, so there is no energy transmission, and filtering is achieved.

[0077] Based on the above structure, the filter body is placed in the middle of the two magnetic poles of the electromagnet magnetic field, and the magnetic field ranges from 3600Oe to 12000Oe. Figure 6 As shown in the figure, the test results of the integrated adjustable bandpass filter of this embodiment are shown. When the magnetic field size is 3600Oe, the corresponding filter center frequency is 5GHz, the 3dB bandwidth is about 30MHz, the insertion loss is about 5.5dB, and the out-of-band suppression is greater than 80dBc; when the external magnetic field size is 12000Oe, the corresponding filter center frequency is 27GHz, the 3dB bandwidth is about 60MHz, the insertion loss is about 4.5dB, and the out-of-band suppression is greater than 80dBc. According to the simulation results, it can be seen that as the magnetic field gradually increases, the center frequency of the filter gradually moves to high frequency, but the 3dB bandwidth and out-of-band suppression of the filter can be basically kept unchanged.

[0078] In the implementation of the integrated adjustable bandpass filter of the present invention, the performance of the filter design is closely related to the coupling between the resonators and the coupling between the input and output and the resonator. Therefore, the distance between the input and output strip lines and the coupling strip lines and the YIG resonator needs to be precisely controlled. Since the LTCC process is highly flexible in the design of the thickness of the raw porcelain strip, there are many optional thicknesses, and the thinnest can be about 5 microns. Therefore, compared with the traditional YIG filter design that requires precision machining and precision assembly to achieve, the present invention can achieve the required coupling more accurately. Using the LTCC process, the filter can be made into an integrated unit, and the assembly is also simpler, without the need for additional processing of the strip lines, etc. The LTCC process can directly slot, which is more accurate for the fixation and position control of the YIG thin film structure, and no subsequent adjustment is required. This filter has no parasitic passband outside the band, and the out-of-band suppression reaches more than 100dBc. At the same time, the 3dB bandwidth can remain basically unchanged within the tuning range, the insertion loss is small, and the in-band standing wave is good.

[0079] like Figure 4As shown, the YIG thin film structure 16 includes a gadolinium gallium garnet substrate 20 and a YIG thin film 21 covering the gadolinium gallium garnet substrate 20, and the YIG thin film structure 16 is manufactured by liquid phase epitaxy technology and has a rectangular shape.

[0080] It should also be pointed out that the additional metal through-holes provided on the green ceramic sheet medium are grounded to provide a shielding effect.

[0081] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An integrated tunable filter, comprising a tunable filter body (23), wherein an input stripline (11), an output stripline (12), a coupling stripline group and a YIG thin film structure group are arranged in the tunable filter body (23), wherein the input stripline (11) can transmit signals with the output stripline (12) through the coupling stripline group and the YIG thin film structure group, and wherein: The tunable filter body (23) is also provided with multiple layers of raw ceramic medium, and the multiple layers of raw ceramic medium are stacked and sintered to form a coupling cavity of the tunable filter body (23), a metal circuit image can be printed on the raw ceramic medium, and a resonant cavity for placing a YIG thin film structure group can be dug out on the raw ceramic medium.

2. The integrated tunable filter according to claim 1, characterized in that: Five layers of raw ceramic medium are arranged in the tunable filter body (23), and the five layers of raw ceramic medium are, from top to bottom, a first layer of raw ceramic medium (1), a second layer of raw ceramic medium (4), a third layer of raw ceramic medium (6), a fourth layer of raw ceramic medium (7) and a fifth layer of raw ceramic medium (8); The first layer of raw ceramic medium (1) and the fourth layer of raw ceramic medium (7) are raw ceramic mediums without metal circuit patterns; The second layer of raw ceramic medium (4) and the fifth layer of raw ceramic medium (8) are raw ceramic medium printed with metal circuit patterns; The third layer of raw ceramic sheet medium (6) is a raw ceramic sheet medium with holes dug therein, and the holes are used to place the YIG thin film structure group.

3. The integrated tunable filter according to claim 2, characterized in that: An input port (18) and an output port (19) are provided on the first layer of raw ceramic sheet medium (1), and the input port (18) and the output port (19) are respectively located on two sides of the first layer of raw ceramic sheet medium (1); The metal circuit image printed on the second layer of raw ceramic sheet medium (4) is an input strip line (11), an output strip line (12) and a first coupling strip line group, and one end of the input strip line (11) is connected to the input port (18) through a metal through hole (17) arranged between the five layers of raw ceramic sheet medium, and one end of the output strip line (12) is connected to the output port (19) through a metal through hole (17) arranged between the five layers of raw ceramic sheet medium, and the first coupling strip line group is located between the input strip line (11) and the output strip line (12); The metal circuit image printed on the fifth layer of raw ceramic sheet medium (8) is a second coupling strip line group.

4. The integrated tunable filter according to claim 3, characterized in that: The input port (18) and the output port (19) are located on the upper surface of the first layer of raw ceramic medium (1); The input strip line (11), the output strip line (12) and the first coupling strip line group are located on the upper surface of the second layer of raw ceramic medium (4); The second coupling strip line group is located on the upper surface of the fifth layer of raw ceramic medium (8).

5. An integrated tunable filter according to claim 3 or 4, characterized in that: The third layer of raw ceramic sheet medium (6) is provided with four through-holes, and the YIG thin film structure group includes four YIG thin film structures (16). The four YIG thin film structures (16) are respectively arranged in the four through-holes to form an input resonator, a second resonator, a third resonator and an output resonator in a signal transmission sequence.

6. The integrated tunable filter according to claim 5, characterized in that: The first coupling strip line group comprises a first coupling strip line (13), and the second coupling strip line group comprises a second coupling strip line (14) and a third coupling strip line (15).

7. The integrated tunable filter according to claim 6, characterized in that: The input strip line (11) is located above the input resonator, and the terminal is grounded, and the downward projection of the input strip line (11) can fall on the input resonator; The output strip line (12) is located above the output resonator, and the terminal is grounded, and the downward projection of the output strip line (12) can fall on the output resonator; The second coupling strip line (14) is located below the input resonator and the second resonator, and the upward projection of the second coupling strip line (14) can fall on the input resonator and the second resonator; The third coupling strip line (15) is located below the third resonator and the output resonator, and the upward projection of the second coupling strip line (14) can fall on the third resonator and the output resonator; The first coupling strip line (13) is located above the second resonator and the third resonator, and a downward projection of the first coupling strip line (13) can fall on the second resonator and the third resonator.

8. The integrated tunable filter according to claim 6, characterized in that: The input strip line (11) and the second coupling strip line (14) are arranged to cross each other, and the included angle is 45° to 90°; The output strip line (12) and the third coupling strip line (15) are arranged to cross each other, and the included angle is 45° to 90°; The two ends of the first coupling strip line (13) are respectively arranged to cross the second coupling strip line (14) and the third coupling strip line (15), and the included angle is 45° to 90°.

9. The integrated tunable filter according to claim 6, characterized in that: The spacing between the input strip line (11), the output strip line (12), the first coupling strip line (13) and the four YIG thin film structures (16) is adjusted by adjusting the thickness of the second layer of raw ceramic medium (4); The spacing between the second coupling strip line (14), the third coupling strip line (15) and the four YIG thin film structures (16) is adjusted by adjusting the thickness of the fourth layer of raw ceramic medium (7).

10. The integrated tunable filter according to claim 5, characterized in that: The YIG thin film structure (16) comprises a gadolinium gallium garnet substrate (20) and a YIG thin film (21) covering the gadolinium gallium garnet substrate (20), and the YIG thin film structure (16) is manufactured using liquid phase epitaxy technology and has a rectangular parallelepiped shape.

Images