A miniaturized three-passband filter of a substrate integrated waveguide in-line strip resonator

Abstract

The application discloses a miniaturized three-passband filter of a substrate integrated waveguide built-in stripline resonator, which is composed of two SIW resonators, two one-end short-circuit and the other-end open-circuit lambda / 4 stripline resonators and two two-end open-circuit lambda / 2 stripline resonators, and the resonators form a three-passband filter in a series topology structure. The application utilizes the TE101 mode of the two SIW resonators, firstly, two one-end short-circuit and the other-end open-circuit lambda / 4 stripline resonators are symmetrically placed in the two SIW resonators to form a two-stage point and double-passband filter, and on the basis, the two one-end short-circuit and the other-end open-circuit lambda / 4 stripline resonators are coupled with the two two-end open-circuit lambda / 2 stripline resonators to form a two-stage point and three-passband filter. By embedding four stripline resonators in the SIW cavity, the miniaturization of the overall structure is realized, and the circuit area can be significantly reduced by about two-thirds while the number and order of passbands are maintained.

Description

Technical Field

[0001] This invention relates to the field of microwave technology, and in particular to a miniaturized three-pass band filter with a substrate integrated waveguide built-in stripline resonator. Background Technology

[0002] With the rapid development of modern wireless communication systems, such as 6G mobile communication and satellite communication, spectrum resources are becoming increasingly scarce. To achieve parallel processing and transmission of multi-band, multi-standard signals in a single communication terminal or base station, the radio frequency front-end system must integrate devices capable of simultaneously processing signals from multiple frequency bands. Microwave multi-passband filters, as key passive components, allow signals from multiple specific frequency bands to pass through with extremely low loss while suppressing interference signals outside the passband, thereby ensuring the capacity, efficiency, and anti-interference capability of the communication system. Substrate integrated waveguide (SIW) technology, with its advantages of low cost, low loss, high power handling capability, and ease of integration, provides an attractive solution for the design of high-performance and low-cost multi-passband filters.

[0003] For various wireless communication applications, researchers have proposed a variety of integrated design methods for SIW three-band filters, such as passband parallel technology and multimode coupling technology. The former connects three cavities with different operating frequency bands in parallel. This method allows for the independent design of three passbands, but the designed filters are often large in size. The latter uses multiple modes in the resonant cavity to couple with each other to form three passbands. Although the size is optimized, the modes of the multimode resonator used are often interdependent, which makes it impossible to freely adjust the passband position and coupling coefficient. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a miniaturized three-pass band filter with a built-in stripline resonator in a substrate integrated waveguide. By incorporating a λ / 2 stripline resonator and a λ / 4 stripline resonator into the SIW cavity, a three-pass band filter is realized, with an area that is one-third that of the conventional structure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a miniaturized three-pass band filter with a substrate-integrated waveguide and a built-in stripline resonator, comprising:

[0006] Dielectric layer (1);

[0007] The top metal layer (2) is located on the upper surface of the dielectric layer (1);

[0008] The bottom metal layer (3) is located on the lower surface of the dielectric layer (1);

[0009] The first metallized via array (4) penetrates the dielectric layer (1) and connects the top metal layer (2) and the bottom metal layer (3).

[0010] First input port (11), first output port (12);

[0011] The first SIW resonator (5) and the second SIW resonator (6) are constructed by a dielectric layer (1), a top metal layer (2), a bottom metal layer (3), and a first metallized via array (4); the first SIW resonator (5) and the second SIW resonator (6) are connected by a coupling window on a common sidewall; the outer sidewalls of the first SIW resonator (5) and the second SIW resonator (6) each have a first window and a second window.

[0012] It also includes a first λ / 4 stripline resonator (7) with one end short-circuited and the other end open-circuited, and a second λ / 4 stripline resonator (8) with one end short-circuited and the other end open-circuited, which are symmetrically located within the first SIW resonator (5) and the second SIW resonator (6), respectively.

[0013] It also includes a first λ / 2 stripline resonator (9) with open circuits at both ends and a second λ / 2 stripline resonator (10) symmetrically located within the first SIW resonator (5) and the second SIW resonator (6), respectively.

[0014] In a preferred embodiment, the striplines of the first λ / 4 stripline resonator (7), the second λ / 4 stripline resonator (8), the first λ / 2 stripline resonator (9), and the second λ / 2 stripline resonator (10) are located at half the height of the dielectric layer (1).

[0015] In a preferred embodiment, the distance between the first λ / 4 stripline resonator (7) and the second λ / 4 stripline resonator (8) and the center of the SIW cavity is T1.

[0016] In a preferred embodiment, the blind hole diameter D1 and the stripline width W1 of the first λ / 4 stripline resonator and the second λ / 4 stripline resonator, which are both short-circuited at one end and open-circuited at the other end, are the same.

[0017] In a preferred embodiment, the coupling distance between the first λ / 4 stripline resonator (7), the second λ / 4 stripline resonator (8), the first λ / 2 stripline resonator (9), and the second λ / 2 stripline resonator (10) is L2. The stripline width W2 of the first λ / 2 stripline resonator (9) and the second λ / 2 stripline resonator (10) is the same. The cavity width W of the first SIW resonator (5) and the second SIW resonator (6) is the same, the cavity length L is the same, and the coupling window is located at the center.

[0018] In a preferred embodiment, an electromagnetic signal is input from the first input port (11) to excite the first SIW resonator (5) and the second SIW resonator (6), and the first SIW resonator (5) and the second SIW resonator (6) are coupled with the first λ / 4 stripline resonator (7) and the second λ / 4 stripline resonator (8).

[0019] In a preferred embodiment, the first input port (11) and the first output port (12) are orthogonal ports. Utilizing the characteristics of orthogonal ports, the electromagnetic signal is input from the first input port (11), which cannot excite higher-order mode TE. 201 The pattern can stimulate higher-order modes TE 102 The first SIW resonator (5) is coupled to the second SIW resonator (6) through a common sidewall coupling cavity, and the higher-order mode TE... 102 The mode has the weakest electric field and cannot excite TE. 102 This mode improves stopband performance.

[0020] In a preferred embodiment, the first input port (11) and the first output port (12) are specifically the first feed microstrip line and the second feed microstrip line, respectively, with a 50-ohm impedance, and the distance between their center lines and the center line of the SIW cavity is T.

[0021] In a preferred embodiment, the first metallized via array (4) is composed of a plurality of periodically distributed first metallized vias.

[0022] In a preferred embodiment, the dielectric layer (1) is formed by stacking two dielectric substrates one on top of the other.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention realizes a three-pass band filter by embedding a λ / 2 stripline resonator and a λ / 4 stripline resonator in the SIW cavity, with an area that is one-third of that of the traditional structure.

[0025] (2) The coupling of the λ / 4 stripline resonator and the λ / 2 stripline resonator of the present invention can be controlled independently, and the design is relatively simple.

[0026] (3) The resonant frequencies of the λ / 4 stripline resonator and the λ / 2 stripline resonator of the present invention can be controlled independently, and the three bandwidths can be controlled by changing the frequency. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural schematic diagram of the three-pass band filter provided in this embodiment;

[0028] Figure 2 This is a side view schematic diagram of the three-pass band filter provided in this embodiment;

[0029] Figure 3 This is a top view of the three-passband filter provided in this embodiment;

[0030] Figure 4 This is a diagram showing the electric field amplitude distribution of the first, second, and third modes of the resonator provided in this embodiment;

[0031] Figure 5 This is the topology diagram of the three-pass band filter provided in this embodiment. S / L represent the source and load, respectively. 1 and 2 represent the resonance modes of the SIW resonator, i.e., the first mode. 3 and 4 represent the resonance modes of the λ / 4 stripline resonator, i.e., the second mode. 5 and 6 represent the resonance modes of the λ / 2 stripline resonator, i.e., the third mode.

[0032] Figure 6 This embodiment shows the curve of the coupling coefficient K13 between the λ / 4 stripline resonator and the SIW resonator when the blind hole diameter D1, the stripline width W1, and the distance from the center position T1 are changed.

[0033] Figure 7 These are the coupling coefficient K35 variation curves of the λ / 4 stripline resonator and the λ / 2 stripline resonator provided in this embodiment;

[0034] Figure 8 The curves show how the resonant frequency and the no-load quality factor (Qu) of the λ / 2 stripline resonator change with the length L3.

[0035] Figure 9 The curves show how the resonant frequency and Qu change with the length L4 of the λ / 4 stripline resonator.

[0036] Figure 10 The curves show how the resonant frequency and Qu change with the length L of the SIW resonator.

[0037] Figure 11 This is the S-parameter curve of the three-passband filter provided in this embodiment;

[0038] The markings in the diagram are: 1. Dielectric layer; 2. Top metal layer; 3. Bottom metal layer; 4. First metallized via array; 5. First SIW resonator; 6. Second SIW resonator; 7. First λ / 4 stripline resonator; 8. Second λ / 4 stripline resonator; 9. First λ / 2 stripline resonator; 10. Second λ / 2 stripline resonator; 11. First input port; 12. First output port. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] like Figure 1 As shown, this embodiment provides a miniaturized three-band filter with a substrate integrated waveguide and a built-in stripline resonator. The first band operates around 8.9 GHz, the second band around 9.5 GHz, and the third band around 10.2 GHz. The second and third bands of the three-band filter are constructed using a first λ / 4 stripline resonator 7 with one end open and one end short, a second λ / 4 stripline resonator 8 with one end open and one end short, a first SIW resonator 5, and a second SIW resonator 6. The bandwidth allocation of the second and third bands is achieved by adjusting the blind aperture diameter D1, the stripline width W1, the length L4, and the distance from the center T1. The first band of the three-band filter is constructed by coupling two λ / 2 striplines with both ends open to two λ / 4 stripline resonators with one end open and one end short. This significantly reduces the circuit size. At the same time, the required external quality factor and coupling coefficient can be easily obtained by changing the input and output port positions and coupling window, achieving adjustable bandwidth and simple design. Specifically, it includes: a dielectric layer 1, a top metal layer 2 located on the upper surface of the dielectric layer 1, a bottom metal layer 3 located within the dielectric layer 1, a first metallized via array 4, a first λ / 4 stripline resonator 7, a second λ / 4 stripline resonator 8, a first λ / 2 stripline resonator 9, a second λ / 2 stripline resonator 10, a first input port 11, and a first output port 12.

[0043] For example, dielectric layer 1 is formed by stacking two dielectric substrates one on top of the other. Specifically, the dielectric substrate is a TanconicTLY-5 dielectric substrate with a relative permittivity of 2.2, a loss tangent of 0.0009, and a thickness of 0.508 mm.

[0044] The first metallized via array 4 is composed of multiple periodically distributed first metallized vias, which penetrate the dielectric layer 2 and connect the top metal layer 2 and the bottom metal layer 3.

[0045] The resonator is composed of a dielectric layer 1, a top metal layer 2, a bottom metal layer 3, a first metallized via array 4, a first λ / 4 stripline resonator 7, a second λ / 4 stripline resonator 8, a first λ / 2 stripline resonator 9, and a second λ / 2 stripline resonator 10. The resonator includes a first SIW resonator 5, a second SIW resonator 6, a first λ / 4 stripline resonator 7, a second λ / 4 stripline resonator 8, a first λ / 2 stripline resonator 9, and a second λ / 2 stripline resonator 10 arranged side by side and connected.

[0046] The first SIW resonator 5 and the second SIW resonator 6 share a common sidewall, and a first coupling window L1 is opened on the common sidewall.

[0047] Figure 2 This is a side view schematic diagram of this embodiment. The height H1 of the grounding blind hole is half the height of the dielectric layer, and the height H2 of the stripline is twice that of the metal layer, located on the center line of the dielectric layer 1. The height of the dielectric layer 1 is 0.508 mm.

[0048] The first input port 11 and the first output port 12 are specifically the first microstrip line and the second microstrip line, respectively, both with a 50-ohm impedance, a width of Pw, and a deviation from the cavity centerline of T.

[0049] Figure 3 This is a schematic diagram of the parameters of each component in the top metal layer 2 of this embodiment. The distance between the two λ / 4 stripline resonators 7 (short-circuited at one end) and 8 (open-circuited at the other end) and the center of the SIW cavity is T1. The blind hole diameter D1 and stripline width W1 of the first λ / 4 stripline resonator 7 and the second λ / 4 stripline resonator 8 are the same. The coupling distance between the two λ / 2 stripline resonators 9 and 10 (open-circuited at both ends) and the first λ / 4 stripline resonator 7 and the second λ / 4 stripline resonator 8 is L2. The stripline width W2 of the first λ / 2 stripline resonator 9 and the second λ / 2 stripline resonator 10 is the same. The two SIW cavities have the same width W and the same cavity length L, and the coupling window is located at the center.

[0050] Table 1. Dimensions of the three-pass band filter (unit: mm)

[0051]

[0052] The implementation process of the three-passband filter provided in the above embodiment is as follows:

[0053] The electromagnetic signal is input through the first input port 11 and enters the first SIW resonator 5, where it excites the working mode field distribution. The first SIW resonator 5 and the second SIW resonator 6 have a first coupling window L1 on their common sidewall to facilitate electromagnetic energy transfer between the two cavities. This allows the signal to couple into the second SIW resonator 6 through window L1, thus forming a two-stage point bandpass filter structure composed of two SIW cavities. To achieve frequency splitting of the two-stage point bandpass response, λ / 4 stripline resonators with one end short-circuited and the other end open-circuited are arranged symmetrically within the cavities of the first SIW resonator 5 and the second SIW resonator 6. These resonators can strongly couple with the eigenmodes of the cavity and disturb the passband position, splitting the original single bandpass response into two independent passbands. The center frequencies and frequency ratios of the two passbands after splitting can be precisely controlled by adjusting structural parameters such as the diameter D1 of the blind aperture in the cavity, the linewidth W1 and length L4 of the stripline resonator, and the offset distance T1 of the resonator relative to the cavity center. Furthermore, λ / 2 stripline resonators with open ends are symmetrically arranged on both sides of the aforementioned λ / 4 stripline resonator. These λ / 2 resonators, together with the λ / 4 resonator and the SIW cavity, can further split the existing two-passband response, thereby expanding the original two passbands into three independent passbands, realizing the function of a three-passband filter. The bandwidth, bandwidth ratio, and passband spacing of the three passbands can be adjusted by jointly adjusting the blind aperture diameter D1, the width W1, lengths L4 and L3 of the stripline resonator, the coupling distance L2 between the two types of stripline resonators, and the offset position T1 of the resonator relative to the cavity center. These parameters significantly affect the cavity mode, the intrinsic resonant frequency of the stripline resonator, and the coupling strength between different resonators. This allows the three-passband filter of this invention to achieve high degree of freedom in frequency band tunability and bandwidth control within a compact structure, significantly improving the design flexibility and integration of the filter.

[0054] Both the first input port 11 and the first output port 12 employ a mutually orthogonal excitation method. Due to the directional selectivity of the field distribution between the orthogonal ports, when an electromagnetic signal is injected through the first input port 11, the direction of the excited electric field differs from the field distribution characteristics of each resonant mode within the integrated waveguide cavity of the substrate. Therefore, only a portion of specific resonant modes can be effectively excited. Specifically, the orthogonal ports can suppress the influence of the TE signal on the field distribution. 201 The coupling of the modules prevents the higher-order module from being excited at the input port; while for TE 102 The mode, due to the matching relationship between its electric field direction and the excitation field component at the input port, can still be excited within the first SIW resonant cavity 5. Furthermore, energy transfer is achieved between the first SIW resonator 5 and the second SIW resonator 6 through a coupling cavity formed by a common sidewall. In this coupling path, TE...102 The electric field strength of the mode is significantly reduced in the common sidewall region, and its coupling efficiency is much lower than that of the fundamental mode TE. 101 Therefore, the higher-order mode TE cannot form an effective excitation in the second SIW resonator 6. Through this mechanism, the present invention achieves higher-order mode TE in the transmission path. 102 Self-suppression is achieved, preventing it from participating in cross-cavity energy coupling. Based on the mode selection characteristics of the orthogonal ports and the cross-cavity coupling suppression mechanism, this invention can significantly suppress parasitic transmission of higher-order modes outside the passband, thereby effectively improving the stopband performance of the filter and enhancing the overall selectivity of the three-passband filter.

[0055] Figure 4 This is the electric field distribution of the resonant modes of the three resonators of the present invention. The first mode represents the fundamental mode of the SIW resonator, the second mode represents the fundamental mode of the λ / 4 resonator, and the third mode represents the fundamental mode of the λ / 2 resonator.

[0056] Figure 5 This is the topology diagram of the three-pass band filter of the present invention. S represents the first input port, L represents the first output port, A and B represent the fundamental modes of the first SIW resonator 5 and the second SIW resonator 6, C and D represent the first λ / 4 resonator 7 and the second λ / 4 resonator 8, and E and F represent the first λ / 2 resonator 9 and the second λ / 2 resonator 10.

[0057] Figure 6 The coupling coefficient K between the first λ / 4 resonator 7 and the second λ / 4 resonator 8 and the first SIW resonator 1 and the second SIW resonator 2 is... 13 As the blind hole diameter D1 increases, the coupling coefficient K... 13 As the width W1 of the first stripline increases, the coupling coefficient K increases. 13 As the deviation from T1 increases, the coupling coefficient K increases. 13 Increase.

[0058] Figure 7 The coupling coefficient K between the first λ / 4 resonator 7 and the second λ / 4 resonator 8 and the first λ / 2 resonator 9 and the second λ / 2 resonator 10 is... 35 When the spacing L2 between the first λ / 4 resonator 7 and the second λ / 4 resonator 8 and the first λ / 2 resonator 9 and the second λ / 2 resonator 10 increases, the coupling coefficient K... 35 Decrease.

[0059] Figure 8 The figure shows the curves of the resonant frequency and Qu gradually decreasing with the increase of length L3 in the λ / 2 stripline resonator of the three-pass band filter provided in this embodiment. As shown in the figure, Qu of the stripline is 246 at 10 GHz, while Qu of the microstrip line is 152.

[0060] Figure 9The figure shows the curve of the resonant frequency and Qu gradually decreasing as the length L4 increases in the λ / 4 stripline resonator of the three-pass band filter provided in this embodiment. As shown in the figure, Qu is 235 for the stripline and 152 for the microstrip line at 10 GHz.

[0061] Figure 10 The figure shows the curve of the SIW resonator in the three-passband filter provided in this embodiment, where the resonant frequency and Qu gradually decrease as the length L increases. As shown in the figure, at 10 GHz, the Qu of the SIW is 437.

[0062] Figure 11 This is the S-parameter curve of the three-band filter of the present invention. The center frequency of the first band is 8.9 GHz and the relative bandwidth is 2.6%, the insertion loss of the first band is 1.6 dB and the return loss is greater than 20 dB. The center frequency of the second band is 9.5 GHz and the relative bandwidth is 2.1%, the insertion loss of the second band is 2.06 dB and the return loss is greater than 20 dB. The center frequency of the third band is 10.2 GHz and the relative bandwidth is 3.6%, the insertion loss of the first band is 1.3 dB and the return loss is greater than 20 dB. There are two zeros: the first zero is located at 9.2 GHz and the second zero is located at 9.9 GHz.

[0063] In summary, this invention innovatively integrates a stripline resonator within the SIW cavity, reducing the area by approximately two-thirds compared to existing SIW three-passband filters. While achieving miniaturization of the three-passband filter, it also offers advantages such as adjustable bandwidth and flexible frequency ratio, making it suitable for the urgent needs of modern wireless communication systems for high-performance, small-size RF front-end devices.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A miniaturized three-passband filter with a substrate-integrated waveguide-embedded stripline resonator, characterized in that, include: Dielectric layer (1); The top metal layer (2) is located on the upper surface of the dielectric layer (1); The bottom metal layer (3) is located on the lower surface of the dielectric layer (1); The first metallized via array (4) penetrates the dielectric layer (1) and connects the top metal layer (2) and the bottom metal layer (3). First input port (11), first output port (12); The first SIW resonator (5) and the second SIW resonator (6) are constructed by a dielectric layer (1), a top metal layer (2), a bottom metal layer (3), and a first metallized via array (4); the first SIW resonator (5) and the second SIW resonator (6) are connected by a coupling window on a common sidewall; the outer sidewalls of the first SIW resonator (5) and the second SIW resonator (6) each have a first window and a second window. It also includes a first λ / 4 stripline resonator (7) with one end short-circuited and the other end open-circuited, and a second λ / 4 stripline resonator (8) with one end short-circuited and the other end open-circuited, which are symmetrically located within the first SIW resonator (5) and the second SIW resonator (6), respectively. It also includes a first λ / 2 stripline resonator (9) with open circuits at both ends and a second λ / 2 stripline resonator (10) symmetrically located within the first SIW resonator (5) and the second SIW resonator (6), respectively.

2. The miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The striplines of the first λ / 4 stripline resonator (7), the second λ / 4 stripline resonator (8), the first λ / 2 stripline resonator (9), and the second λ / 2 stripline resonator (10) are located at half the height of the dielectric layer (1).

3. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The distance between the first λ / 4 stripline resonator (7) and the second λ / 4 stripline resonator (8) and the center of the SIW cavity is T1.

4. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The blind hole diameter D1 and the stripline width W1 of the first λ / 4 stripline resonator and the second λ / 4 stripline resonator, which are both short-circuited at one end and open-circuited at the other end, are the same.

5. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The coupling distance between the first λ / 4 stripline resonator (7), the second λ / 4 stripline resonator (8), the first λ / 2 stripline resonator (9), and the second λ / 2 stripline resonator (10) is L2. The stripline width W2 of the first λ / 2 stripline resonator (9) and the second λ / 2 stripline resonator (10) is the same. The first SIW resonator (5) and the second SIW resonator (6) have the same cavity width W and the same cavity length L, and the coupling window is located at the center.

6. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, An electromagnetic signal is input from the first input port (11) to excite the first SIW resonator (5) and the second SIW resonator (6). The first SIW resonator (5) and the second SIW resonator (6) are coupled with the first λ / 4 stripline resonator (7) and the second λ / 4 stripline resonator (8).

7. A miniaturized three-pass band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The first input port (11) and the first output port (12) are orthogonal ports. Utilizing the characteristics of orthogonal ports, the electromagnetic signal is input from the first input port (11), which cannot excite higher-order mode TE. 201 The pattern can stimulate higher-order modes TE 102 The first SIW resonator (5) is coupled to the second SIW resonator (6) through a common sidewall coupling cavity, and the higher-order mode TE... 102 The mode has the weakest electric field and cannot excite TE. 102 This mode improves stopband performance.

8. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The first input port (11) and the first output port (12) are specifically the first feed microstrip line and the second feed microstrip line, respectively, with a 50-ohm impedance, and the distance between their center lines and the center line of the SIW cavity is T.

9. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The first metallized via array (4) consists of multiple periodically distributed first metallized vias.

10. A miniaturized three-band filter with a built-in stripline resonator in a substrate integrated waveguide according to claim 1, characterized in that, The dielectric layer (1) is composed of two dielectric plates stacked one on top of the other.

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