Non-reflection band-pass filter based on Wilkinson power divider and rectangular substrate integrated waveguide resonator

Abstract

The invention discloses a non-reflection band-pass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator. According to the non-reflection band-pass filter, a complementary symmetrical structure is adopted, an isolation resistor on a transmission axis is used as an absorption resistor, and the non-reflection band-pass filter is different from a traditional reflected signal eliminating method. Due to the characteristics of the two paths of reflected signals, the phase difference is 180 degrees, mutual counteraction is achieved, and the mutual counteraction effect of the reflected signals is good. In the frequency selection process, a microstrip line is not directly used, the SIW technology is adopted, the resonant cavity is used as a transmission medium, compared with microstrip line transmission, the band-pass filter has higher power capacity and quality factor, and due to the design, the band-pass filter can work on a higher frequency wave band. The filter designed by the invention keeps very low profile height and is easy to process and produce.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave communication, and particularly relates to a non-reflection band-pass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator. BACKGROUND

[0002] With the continuous evolution of modern wireless communication technology and the continuous emergence of emerging application scenarios, existing wireless communication systems are facing more severe performance challenges. As a core component of the radio frequency front end, the performance of the filter circuit directly determines the quality of the entire wireless communication system. Especially in a multi-frequency and multi-mode complex system, the traditional reflection-type filter circuit will reflect the out-of-band noise and spurious energy back to the front-stage non-linear active circuit, causing interference to the key devices such as amplifiers and mixers, thereby reducing the system stability and dynamic range. To solve this key problem, non-reflection filter circuits have emerged. Unlike the traditional reflection-type structure, the non-reflection filter circuit can absorb rather than reflect the unwanted signal energy in the stopband, fundamentally improving the stability and working reliability of the system. For this reason, how to design a high-performance non-reflection filter circuit has become a research hotspot.

[0003] On the other hand, X-band radio waves with a frequency range of 8-12GHz have been widely used in radar and satellite communication fields. Not only that, but this frequency band also serves agricultural monitoring, environmental monitoring and other work. Therefore, the research on non-reflection filter circuits based on the X-band has important significance for improving the performance of radar and satellite communication electronic equipment.

[0004] Currently, there are mainly three ways to achieve the design of reflectionless filter circuit: the first is the odd-even mode circuit cancellation method based on symmetric circuit, which constructs a symmetric lossy two-port filter network through lumped elements, and makes the odd mode and even mode equivalent circuits have opposite input reflection coefficients, so as to achieve the effect of no reflection of out-of-band signals. Although this method has the advantage of compact structure due to the use of lumped elements, it faces problems such as difficulty in controlling parasitic parameters and limited bandwidth adjustment of passband. The second method uses a complementary duplexer structure to realize a reflectionless filter, which consists of a main bandpass channel and an auxiliary bandstop channel, both of which have complementary filter responses. However, in actual design, it is difficult to achieve complementary filter responses of the main channel and the auxiliary channel, resulting in increased insertion loss at the passband edge. In addition, the auxiliary channel needs to be designed and optimized in coordination with the main channel filter response, increasing the design tuning complexity. If double-port reflectionlessness is to be achieved, two auxiliary channels need to be set at the input and output ports, which will significantly increase the circuit size in high-order applications. The third method is a balanced configuration based on double channels, which uses two hybrid connectors as input and output ports to construct two symmetric transmission channels, each channel placing the same reflective filter unit and quarter-wave delay line. Although the implementation principle is clear, the reflectionless performance of the designed filter is often limited by the performance of the power divider and the phase shift performance of the delay line, and it is difficult to achieve integration and miniaturization design. In addition, from the current reported technical approaches, due to the inherent characteristics and structural form requirements of the technology, the reflectionless filter circuits designed by the above methods are mainly concentrated in low working frequencies. When migrating to higher working frequency bands such as X-band, they often face the limitations of reduced reflectionless performance, increased in-band insertion loss, and low power capacity.

[0005] In summary, the current reflectionless filter circuit still faces problems such as the need to improve working performance, limited working frequency band, and low structural integration. Therefore, it is of great application value to develop a new type of reflectionless filter circuit with good in-band transmission and out-of-band reflectionless characteristics and high structural integration at high working frequency bands in modern radar and satellite communication systems. SUMMARY

[0006] The present application aims to solve the problems of the prior art and provides a reflectionless filter working in X-band with high selectivity, large power capacity and high structural integration.

[0007] The technical solution to achieve the purpose of the present application is a reflectionless bandpass filter based on Wilkinson power divider and rectangular substrate integrated waveguide resonator, which comprises an upper layer metal ground, an upper layer dielectric substrate, a circuit layer, an intermediate dielectric substrate, a resonant cavity, a lower layer dielectric substrate and a lower layer metal ground arranged from top to bottom.

[0008] The upper metal ground is provided with two sets of isolation resistors, which are symmetrically arranged about the first central axis of the upper metal ground and connected to the circuit layer through metallized vias; the upper metal ground is also provided with two signal transmission feed points, both of which are connected to the circuit layer through metallized vias.

[0009] The circuit layer has two Wilkinson power dividers, namely the first Wilkinson power divider and the second Wilkinson power divider. The two output terminals of each Wilkinson power divider are respectively connected to an open-ended microstrip line and a short-ended microstrip line. The overall structure formed by the two Wilkinson power dividers and the four microstrip lines is centrally symmetrical about the center point of the circuit layer. The end of each short-ended microstrip line is connected to the upper metal ground through a metallized via.

[0010] The resonant cavity includes a first rectangular metal plate and a second rectangular metal plate, which are spliced ​​along the long side of the rectangle and staggered by a certain distance L. Each of the first and second rectangular metal plates has three resonant cavities, designated as the first to the third resonant cavity, respectively. The three resonant cavities are triangularly coupled, and each pair of the three resonant cavities has a coupling window. Two slots are etched on each of the first and second rectangular metal plates, designated as the first slot and the second slot, respectively. The first slot couples to the open-circuit microstrip line at the end of the first Wilkinson power divider, and the second slot couples to the short-circuit microstrip line at the end of the first Wilkinson power divider. The first slot or the second slot couples the input signal sequentially into the first to the third resonant cavity.

[0011] The projections of the open-circuit microstrip line of the first Wilkinson power divider and the short-circuit microstrip line of the second Wilkinson power divider are respectively located in two resonant cavities on the first rectangular metal plate. These two resonant cavities must be able to pass through three resonant cavities in sequence after the input signal enters. The projections of the open-circuit microstrip line of the second Wilkinson power divider and the short-circuit microstrip line of the first Wilkinson power divider are respectively located in two resonant cavities on the second rectangular metal plate. These two resonant cavities must be able to pass through three resonant cavities in sequence after the input signal enters.

[0012] Furthermore, both the upper metal ground layer and the upper dielectric substrate are rectangular structures, and both have the same size.

[0013] Furthermore, the two sets of isolation resistors are arranged along the second central axis of the upper metal ground, and the second central axis is perpendicular to the first central axis.

[0014] Furthermore, the isolation resistors in each group of isolation resistors are arranged at equal intervals.

[0015] Furthermore, both of the aforementioned signal transmission feed points can be used as either input feed terminals or output feed terminals.

[0016] Furthermore, the distance L is one-quarter of a wavelength.

[0017] Furthermore, the coupling windows between each of the three resonant cavities have the same width.

[0018] Furthermore, there is a certain distance L1 between the first gap and the projection of the corresponding terminal open-circuit microstrip line, and the second gap overlaps with the projection of the corresponding terminal short-circuit microstrip line.

[0019] Furthermore, the distance L1 is one-quarter of a wavelength.

[0020] Furthermore, the two signal transmission feed points are symmetrically arranged about the first central axis of the upper metal ground.

[0021] Compared with the prior art, the significant advantages of this invention are:

[0022] (1) It adopts a complementary symmetrical structure and uses the isolation resistor on the transmission axis as the absorption resistor, which is different from the traditional method of eliminating reflected signals.

[0023] (2) Due to the characteristics of the two reflected signals, they are 180° out of phase and cancel each other out, resulting in a good mutual cancellation effect of the reflected signals.

[0024] (3) When selecting the frequency, instead of using microstrip lines directly, SIW technology is used, which uses a resonant cavity as the transmission medium. Compared with microstrip line transmission, it has higher power capacity and quality factor. As a result, this design allows the bandpass filter to operate at a higher frequency band.

[0025] (4) The filter designed in this invention maintains a very low profile height, making it easy to process and manufacture.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of the reflection-free filter of the present invention in one embodiment.

[0028] Figure 2 This is a schematic diagram of the upper metal ground structure of a reflection-free bandpass filter in one embodiment.

[0029] Figure 3 This is a schematic diagram of the Wilkinson power divider circuit structure of a reflection-free bandpass filter in one embodiment.

[0030] Figure 4This is a schematic diagram of the resonant cavity segmented metal ground structure of a reflection-free bandpass filter in one embodiment.

[0031] Figure 5 This is a schematic diagram of the underlying metal ground structure of a reflection-free bandpass filter in one embodiment.

[0032] Figure 6 This is a simulation diagram of the gain curve of a reflection-free bandpass filter in one embodiment. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0034] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0035] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0036] In one embodiment, combined Figures 1 to 5 A reflection-free bandpass filter based on Wilkinson power divider and rectangular substrate integrated waveguide resonator is provided. The reflection-free bandpass filter includes an upper metal ground 1, an upper dielectric substrate 2, a circuit layer 3, an intermediate dielectric substrate 4, a resonant cavity 5, a lower dielectric substrate 6, and a lower metal ground 7 arranged from top to bottom.

[0037] The upper metal ground 1 is provided with two sets of isolation resistors, which are symmetrically arranged about the first central axis of the upper metal ground 1 and connected to the circuit layer 3 through metallized vias; the upper metal ground 1 is also provided with two signal transmission feed points, both of which are connected to the circuit layer 3 through metallized vias.

[0038] Two Wilkinson power dividers are provided on the circuit layer 3, namely the first Wilkinson power divider W1 and the second Wilkinson power divider W2. The two output terminals of each Wilkinson power divider are respectively connected to an open-circuit microstrip line and a short-circuit microstrip line. The overall structure formed by the two Wilkinson power dividers and the four microstrip lines is centrally symmetrical about the center point of the circuit layer 3. The end of each short-circuit microstrip line is connected to the upper metal ground 1 through a metallized via.

[0039] Specifically, the two output terminals of the first Wilkinson power divider W1 are connected to the first open-circuit microstrip line 16a and the first short-circuit microstrip line 17a, respectively, and the two output terminals of the second Wilkinson power divider W2 are connected to the second open-circuit microstrip line 16b and the second short-circuit microstrip line 17b, respectively.

[0040] Specifically, the first terminal short-circuit microstrip line 17a is connected to the upper metal ground 1 through the ninth metallized via 18b, and the second terminal short-circuit microstrip line 17b is connected to the upper metal ground 1 through the tenth metallized via 18e.

[0041] The resonant cavity 5 includes a first rectangular metal plate 5a and a second rectangular metal plate 5b. The first rectangular metal plate 5a and the second rectangular metal plate 5b are spliced ​​along the long side of the rectangle and staggered by a certain distance L. Each of the first rectangular metal plate 5a and the second rectangular metal plate 5b is provided with three resonant cavities, namely the first resonant cavity to the third resonant cavity. The three resonant cavities are coupled in a triangular coupling, i.e., CT coupling, and each pair of the three resonant cavities is provided with a coupling window. Each of the first rectangular metal plate 5a and the second rectangular metal plate 5b is etched with two slits, respectively denoted as the first slit and the second slit. The first slit is coupled to the open-circuit microstrip line at the end of the first Wilkinson power divider W1, and the second slit is coupled to the short-circuit microstrip line at the end of the first Wilkinson power divider W1. The first slit or the second slit couples the input signal into the first resonant cavity to the third resonant cavity in sequence.

[0042] Specifically, the first slit mark 22a and the second slit mark 22c are etched on the first rectangular metal plate 5a, and the first slit mark 22d and the second slit mark 22b are etched on the second rectangular metal plate 5b.

[0043] Specifically, the three coupling windows between each pair of the three resonant cavities on the first rectangular metal plate 5a are denoted as 23a, 24b, and 23c, respectively, and the three coupling windows between each pair of the three resonant cavities on the second rectangular metal plate 5b are denoted as 23b, 24a, and 23d, respectively.

[0044] Specifically, the ninth metallized via 18b and the tenth metallized via 18e are connected to the eleventh metallized via 18c and the twelfth metallized via 18f on the first rectangular metal plate 5a and the second rectangular metal plate 5b, as well as the thirteenth metallized via 18a and the fourteenth metallized via 18d on the upper metal ground 1, so that the terminals of the first terminal short-circuited microstrip line 17a and the second terminal short-circuited microstrip line 17b are grounded to the resonant cavity shell.

[0045] The projections of the open-circuit microstrip line of the first Wilkinson power divider W1 and the short-circuit microstrip line of the second Wilkinson power divider W2 are respectively located in two resonant cavities on the first rectangular metal plate 5a. These two resonant cavities must be able to pass through three resonant cavities in sequence after the input signal enters. The projections of the open-circuit microstrip line of the second Wilkinson power divider W2 and the short-circuit microstrip line of the first Wilkinson power divider W1 are respectively located in two resonant cavities on the second rectangular metal plate 5b. These two resonant cavities must be able to pass through three resonant cavities in sequence after the input signal enters.

[0046] Furthermore, in one embodiment, both the upper metal ground 1 and the upper dielectric substrate 2 are rectangular structures and have the same size.

[0047] In some embodiments, the two sets of isolation resistors are arranged along the second central axis of the upper metal ground 1, and the second central axis is perpendicular to the first central axis.

[0048] Preferably, each group of isolation resistors includes three isolation resistors, which are respectively denoted as first resistor R1, second resistor R2, third resistor R3, fourth resistor R4, fifth resistor R5, and sixth resistor R6; the two ends of each resistor are respectively connected to a third metal via 15a and a fourth metal via 15b on the circuit layer 3 through a first metal via 8a and a second metal via 8b.

[0049] Preferably, the isolation resistors in each group of isolation resistors are arranged at equal intervals.

[0050] Furthermore, in one embodiment, both of the signal transmission feed points can serve as either input feed terminals or output feed terminals.

[0051] Preferably, the two signal transmission feed points are symmetrically arranged about the first central axis of the upper metal ground 1.

[0052] Preferably, the two signal transmission feed points are the fifth metallized via 11a and the sixth metallized via 11b, respectively, and are connected to the seventh metallized via 14a and the eighth metallized via 14b on the circuit layer 3 through feed conductors.

[0053] Furthermore, in one embodiment, the distance L is a quarter wavelength.

[0054] Furthermore, in one embodiment, the three resonant cavities are obtained by dividing one resonant cavity into three chambers using multiple metallized vias indicated by metallized via 25. The metallized vias in the upper metal ground 1, represented by mark 9, are connected to other layers, such as those represented by marks 12, 21, 26, and 28, to form a SIW structure.

[0055] Furthermore, in one embodiment, the coupling windows between each pair of the three resonant cavities have the same width.

[0056] Furthermore, there is a certain distance L1 between the first gap and the projection of the corresponding terminal open-circuit microstrip line, and the second gap overlaps with the projection of the corresponding terminal short-circuit microstrip line.

[0057] Preferably, the distance L1 is one-quarter of a wavelength.

[0058] Preferably, the upper metal ground 1, upper dielectric substrate 2, circuit layer 3, intermediate dielectric substrate 4, resonant cavity 5, lower dielectric substrate 6, and lower metal ground 7 are connected by bolts, such as... Figures 1 to 5 The markings 10a, 10b, 10c, 10d, 13, 19, 20, 27, and 29 are shown in the figure. Preferably, the threaded holes can be symmetrically distributed.

[0059] When a signal enters the circuit through the fifth metallized via 11a, and then through the seventh metallized via 14a into the first slot 22a and the second slot 22b, the TE10 mode inside the rectangular SIW resonator formed by several metallized vias is excited. This TE10 mode then undergoes electromagnetic coupling through the CT structure to reach the opposite end, the second slot 22c and the first slot 22d. After coupling, it reaches the second terminal open-circuit microstrip line 16b and the second terminal short-circuit microstrip line 17b of the Wilkinson power divider, and then reaches the eighth metallized via 14b. Finally, it reaches the sixth metallized via 11b to complete the transmission. The principle for the sixth metallized via 11b is the same and will not be described further.

[0060] Specifically, the signal enters through the fifth metallized via 11a, passes through the seventh metallized via 14a, and reaches the Wilkinson power divider. There, the signal is split into two signals with the same amplitude and phase. The upper part is transmitted in the first open-ended microstrip line 16a, and at a quarter-wavelength from the termination point, a first slit 22a, where the current (electric field) is at its maximum on the transmission line, couples a specific frequency signal into the resonant cavity, exciting a TE10 mode for transmission. The lower part is grounded at its end through the thirteenth metallized via 18a and the ninth metallized via 18b. The signal is transmitted in the short-circuited transmission line. Since the short-circuit point is where the current (electric field) is at its maximum, a second slit 22b at that point can also couple the signal into the resonant cavity. At this point, the signals in both resonant cavities have the same amplitude and phase. When the signal propagates within the resonant cavity, it is coupled into the next resonant cavity through coupling windows 24a and 24b on the intermediate dielectric layer and rectangular coupling structures 23, 23b, 23c, and 23d. The signal passes through three identical resonant cavities in total, improving frequency selectivity. Finally, when the signal is coupled from the resonant cavity to the second open-ended microstrip line 16b and the second short-ended microstrip line 17b, the symmetrical design ensures that the transmitted signal is of equal amplitude and in phase. The signal is then converged by two Wilkinson power dividers to achieve signal transmission.

[0061] For the sixth metallized via 11b, when the signal is reflected, because the input signal has a 90° phase difference between its upper and lower parts after passing through the Wilkinson power divider, and another 90° phase difference is generated during reflection, the two signals will become equal-amplitude, out-of-phase signals when reflected back. These signals then reach the resistor between the two vias through the third metallized via 15a and the fourth metallized via 15b, converting the reflected electrical signal into heat energy for dissipation, thus achieving no reflection at the input. The principle is the same for the sixth metallized via 11b, and will not be elaborated further.

[0062] Figure 6 The image shows a simulated gain curve of a reflectionless bandpass filter. It can be observed that the center frequency of the operating frequency band of the reflectionless bandpass filter is 10 GHz, and the -10 dB bandwidth is 9.53-10.49 GHz. That is, this reflectionless bandpass filter operates in the X-band, and... The value remains below -10dB in the frequency band of 5.07GHz-14.95GHz, maintaining good reflection-free bandpass characteristics.

[0063] In summary, the reflection-free bandpass filter based on the Wilkinson power divider and rectangular substrate integrated waveguide (SIW) resonator of this invention can achieve high frequency selectivity and good out-of-band reflection-free performance in the X-band. It can absorb unwanted out-of-band RF signal echoes over a wide frequency range, thereby preventing interference from the active stage at the front end and improving the stability of the communication system. Furthermore, this invention has advantages such as high structural integration and ease of manufacturing.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention without departing from its spirit and scope should be included within the protection scope of the present invention.

Claims

1. A reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator, characterized in that, The non-reflective bandpass filter includes, from top to bottom, an upper metal ground (1), an upper dielectric substrate (2), a circuit layer (3), an intermediate dielectric substrate (4), a resonant cavity (5), a lower dielectric substrate (6), and a lower metal ground (7). The upper metal ground (1) is provided with two sets of isolation resistors. The two sets of isolation resistors are symmetrically arranged about the first central axis of the upper metal ground (1) and are connected to the circuit layer (3) through metallized vias. The upper metal ground (1) is also provided with two signal transmission feed points, both of which are connected to the circuit layer (3) through metallized vias. Two Wilkinson power dividers are provided on the circuit layer (3), namely the first Wilkinson power divider (W1) and the second Wilkinson power divider (W2). The two output terminals of each Wilkinson power divider are respectively connected to a terminal open-circuit microstrip line and a terminal short-circuit microstrip line. The overall structure composed of the two Wilkinson power dividers and the four microstrip lines is centrally symmetrical about the center point of the circuit layer (3). The end of each terminal short-circuit microstrip line is connected to the upper metal ground (1) through metallized vias (18b 18e). The resonant cavity (5) includes a first rectangular metal plate (5a) and a second rectangular metal plate (5b). The first rectangular metal plate (5a) and the second rectangular metal plate (5b) are spliced ​​along the long side of the rectangle and staggered by a certain distance L. Each of the first rectangular metal plate (5a) and the second rectangular metal plate (5b) is provided with three resonant cavities, namely the first resonant cavity to the third resonant cavity. The three resonant cavities are triangularly coupled, and each pair of the three resonant cavities is provided with a coupling window. Each of the first rectangular metal plate (5a) and the second rectangular metal plate (5b) has two slits etched on it, which are respectively referred to as the first slit and the second slit. The first slit is coupled to the open-circuit microstrip line of the terminal of the first Wilkinson power divider (W1), and the second slit is coupled to the short-circuit microstrip line of the terminal of the first Wilkinson power divider (W1). The first slit or the second slit couples the input signal into the first resonant cavity to the third resonant cavity in sequence. The projections of the open-circuit microstrip line of the first Wilkinson power divider (W1) and the short-circuit microstrip line of the second Wilkinson power divider (W2) are respectively located in two resonant cavities on the first rectangular metal plate (5a). These two resonant cavities must be able to pass through three resonant cavities in sequence after the input signal enters. The projections of the open-circuit microstrip line of the second Wilkinson power divider (W2) and the short-circuit microstrip line of the first Wilkinson power divider (W1) are respectively located in two resonant cavities on the second rectangular metal plate (5b). These two resonant cavities must be able to pass through three resonant cavities in sequence after the input signal enters.

2. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 1, characterized in that, The upper metal ground (1) and the upper dielectric substrate (2) are both rectangular structures and have the same size.

3. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 2, characterized in that, The two sets of isolation resistors are arranged along the second central axis of the upper metal ground (1), and the second central axis is perpendicular to the first central axis.

4. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 3, characterized in that, The isolation resistors in each group are arranged at equal intervals.

5. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 1, characterized in that, Both of the aforementioned signal transmission feed points can be used as either input feed terminals or output feed terminals.

6. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 1, characterized in that, The distance L is one-quarter of the wavelength.

7. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 1, characterized in that, The coupling windows between each of the three resonant cavities have the same width.

8. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 1, characterized in that, There is a certain distance L1 between the first gap and the projection of the corresponding terminal open-circuit microstrip line, and the second gap overlaps with the projection of the corresponding terminal short-circuit microstrip line.

9. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 8, characterized in that, The distance L1 is one-quarter of the wavelength.

10. The reflection-free bandpass filter based on a Wilkinson power divider and a rectangular substrate integrated waveguide resonator according to claim 1, characterized in that, The two signal transmission feed points are symmetrically arranged about the first central axis of the upper metal ground (1).

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