A High-Selectivity Planar Dual-Cavity Dual-Mode Patch Filter

Abstract

This invention relates to a high-selectivity planar dual-cavity dual-mode patch filter, comprising a filter body, which includes a first dual-mode single-cavity unit and a second dual-mode single-cavity unit, with an λg / 4 stripe disposed between the first and second dual-mode single-cavity units. Both the first and second dual-mode single-cavity units are patch structures, each including a patch with an etched cross-slot perturbation structure. The first dual-mode single-cavity unit includes a first resonator and a second resonator, and the second dual-mode single-cavity unit includes a third resonator and a fourth resonator. This invention employs a single-cavity dual-mode box-type topology, possessing multiple coupling paths and introducing four finite-frequency transmission zeros distributed on both sides of the passband, achieving high selectivity. Simultaneously, the patch structure design enables the bandpass filter body to possess high power capacity, making it suitable for integration with most active devices.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic fields and microwave technology, specifically to a highly selective planar dual-cavity dual-mode patch filter. Background Technology

[0002] With the rapid development of science and technology, the demands on wireless communication systems (including 5G / E5G) in military, commercial, and civilian fields are becoming increasingly stringent. As a core component of wireless communication systems, the filter body, in addition to fulfilling the requirements of spectrum resource allocation, filtering unwanted signals, and suppressing interference signals, faces increasingly stringent requirements regarding the physical topology, integrated design methods, design and manufacturing processes and efficiency, device size, and cost of the filter body in the face of the rapid development demands of miniaturization, high power capacity, high selectivity, and low cost in wireless communication systems. For example, the publication CN217719920U, "A dielectric resonant structure, filter body, and communication equipment," illustrates this. Therefore, given the increasingly complex electromagnetic signal environment and the increasingly scarce spectrum allocation resources, it is extremely necessary to research high-selectivity, high-power-capacity, miniaturized, and low-cost filter bodies to adapt to the rapidly developing wireless communication systems.

[0003] While existing technologies employing substrate-integrated waveguide structures to design filter bodies can achieve high quality factors, their excessive size is a problem in current 5G-Sub 6 applications due to their cutoff frequency. Microwave filters offer advantages such as small size and flexible design, but their power capacity is insufficient, which is detrimental to the power requirements of wireless communication systems.

[0004] Therefore, there is an urgent need for a filter device that is small in size, highly selective, has a large power capacity, and low radiation loss. Summary of the Invention

[0005] This invention addresses the problems of narrow bandwidth, poor selectivity, large size, and high radiation loss in existing filters used in 5G-Sub 6 phase technology. It provides a high-selectivity planar dual-cavity dual-mode patch filter, employing a dual-cavity dual-mode patch structure to design a fourth-order filter body, effectively reducing device size and achieving miniaturization. A single-cavity dual-mode box-type topology with multiple coupling paths introduces four finite-frequency transmission zeros distributed on both sides of the passband, achieving high selectivity. Simultaneously, the patch structure design enables the bandpass filter body to have high power capacity, making it suitable for integration with most active devices.

[0006] To achieve the above objectives, this invention proposes a high-selectivity planar dual-cavity dual-mode patch filter, comprising a source feed line, a load feed line, and a filter body. One end of the filter body is connected to a source via the source feed line, and the other end is connected to a load via the load feed line. The filter body includes a first dual-mode single-cavity unit and a second dual-mode single-cavity unit, with a λg / 4 stripe disposed between the first and second dual-mode single-cavity units. Both the first and second dual-mode single-cavity units are patch structures, and the patch structure includes a patch etched with a cross-slot perturbation structure.

[0007] The first dual-mode single-cavity unit includes a first resonator and a second resonator, and the second dual-mode single-cavity unit includes a third resonator and a fourth resonator.

[0008] Where λg represents the waveguide wavelength.

[0009] Specifically, the bandpass filter body consists of two dual-mode single-cavity patches and a λ... g It consists of a 4-strip line, SIW electric wall, source feed line, and load feed line, forming a symmetrical structure.

[0010] The four resonators are composed of two dual-cavity, dual-mode patches, each of which employs a cross-slot perturbation structure to effectively divide the resonant frequency. The resonators operate at TE... 100 and TE 010 model.

[0011] Furthermore, the filter body is provided with a main coupling path and a cross coupling path. The main coupling path includes the source feed line being coupled to the first resonator and the second resonator simultaneously. The first resonator and the second resonator are both coupled to the λg / 4 stripline. The λg / 4 stripline is also coupled to the third resonator and the fourth resonator simultaneously. The third resonator and the fourth resonator are both coupled to the load feed line.

[0012] The cross-coupling path includes a source feeder coupled to a λg / 4 stripe, and a λg / 4 stripe coupled to a load feeder.

[0013] Furthermore, the filter body also includes an upper metal plate, an intermediate dielectric plate and a bottom metal plate. The upper metal plate is also provided with SIW electric walls, which are arranged around the first dual-mode single-cavity unit and the second dual-mode single-cavity unit respectively.

[0014] The upper metal plate and the lower metal plate sandwich the intermediate medium plate.

[0015] The filter body has a "sandwich" structure and is manufactured using single-layer PCB circuit board printing technology. The middle dielectric board only requires a commonly used dielectric substrate, making it more suitable for various applications in the microwave operating frequency band. Therefore, it can meet the needs of miniaturized, low-cost, and wide-range wireless RF systems, and has high market application value.

[0016] The SIW structure can be regarded as an ideal electric wall, which can effectively reduce the radiation loss of the patch filter body.

[0017] Furthermore, the source feed line and load feed line include microstrip lines with an impedance of 50Ω.

[0018] The 50Ω impedance microstrip line is an international standard feed line, which makes it easier to interconnect and integrate with other components.

[0019] Furthermore, the λg / 4 strip has a zigzag folded structure.

[0020] The λg / 4 stripe is folded in shape and connects the first dual-mode single-cavity unit and the second dual-mode single-cavity unit. This can effectively increase the coupling strength between the first and second dual-mode single-cavity units, thus widening the bandwidth of the passband filter. At the same time, the folded design can effectively reduce the size, making the device more miniaturized. By finely adjusting the width and length of the λg / 4 stripe, the coupling strength or ratio between the first and second dual-mode single-cavity units can be controlled, thereby enabling the adjustment of the passband bandwidth or the position of the zero-point frequency of the limited frequency transmission.

[0021] The beneficial effects of the present invention through the above technical solution are as follows:

[0022] 1. This invention employs a dual-mode, dual-cavity patch structure design, etching cross-slot lines to perturb the degeneracy mode of the dual-mode patch, making it suitable for filter design. Physically, it utilizes two patch cavities to design a fourth-order filter body, effectively reducing device size and achieving miniaturization. Simultaneously, the patch structure design enables the bandpass filter body to possess high power capacity, making it suitable for integration with most active devices.

[0023] 2. A dual-mode dual-cavity resonant structure combining a first dual-mode single-cavity unit and a second dual-mode single-cavity unit with a source feed line and a load feed line is adopted. This introduces four finite-frequency transmission zeros into the fourth-order filter body, with two finite-frequency transmission zeros distributed on each side of the passband. This achieves the goal of introducing N (N≥2) finite-frequency transmission zeros into the Nth-order filter body, effectively improving the high selectivity and sideband suppression capability of the bandpass filter body.

[0024] 3. In existing technologies, the coupling between patch cavities generally uses window gap coupling. This type of coupling suffers from weak coupling due to the low edge current density of the patch resonator, resulting in a narrow bandwidth for the filter and limiting its application range. This invention uses λ... g / 4 The strip directly connects the two dual-mode patch cavities, utilizing the discovered λ g The λg / 4 stripe exhibits weak coupling, effectively increasing the coupling strength of the two dual-mode patch resonators without affecting the resonant frequency, thus significantly widening the passband bandwidth. Simultaneously, the λg / 4 stripe employs a folded structure design, further reducing the device size. By fine-tuning the width and length of the λg / 4 stripe, the passband bandwidth and transmission zero position of the bandpass filter can be adjusted, achieving high selectivity.

[0025] 4. SIW electric walls are provided around the first dual-mode single-cavity unit and the second dual-mode single-cavity unit of the present invention. SIW electric walls can be regarded as ideal electric walls in the present invention, which effectively reduces electromagnetic energy radiation leakage of the patch resonator, thereby effectively solving the problem of high radiation loss of the patch filter body.

[0026] 5. The source feed and load feed of the present invention adopt microstrip lines with an impedance of 50 Ω, and the filter body structure adopts a planar structure, which makes it easier to interconnect and integrate with other devices. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a high-selectivity planar dual-cavity dual-mode patch filter according to the present invention;

[0028] Figure 2 This is a three-dimensional structural schematic diagram of a high-selectivity planar dual-cavity dual-mode patch filter according to the present invention;

[0029] Figure 3 This is a schematic diagram of the coupling topology of a high-selectivity planar dual-cavity dual-mode patch filter according to the present invention;

[0030] Figure 4 These are the parameter response curves of the dual-cavity dual-mode patch filter according to an embodiment of the present invention;

[0031] Figure 5 This is an example diagram of a dual-cavity dual-mode patch filter with adjustable finite frequency transmission zeros according to an embodiment of the present invention;

[0032] Figure 6 This is an example diagram of the adjustable bandpass filter bandwidth of the dual-cavity dual-mode patch filter according to an embodiment of the present invention.

[0033] The labels in the attached diagram are as follows: 1 is the source feed line, 2 is the load feed line, 3 is the first dual-mode single cavity, 4 is the second dual-mode single cavity, 5 is the λg / 4 stripline, 6 is the first resonator, 7 is the second resonator, 8 is the third resonator, 9 is the fourth resonator, 10 is the upper metal plate, 11 is the middle dielectric plate, 12 is the bottom metal plate, and 13 is the SIW electric wall. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0035] Example 1

[0036] like Figures 1-3 As shown, a high-selectivity planar dual-cavity dual-mode patch filter includes a source feed line 1, a load feed line 2, and a filter body. One end of the filter body is connected to a source via the source feed line 1, and the other end is connected to a load via the load feed line 2. The filter body comprises a first dual-mode single-cavity unit 3 and a second dual-mode single-cavity unit 4, with a λg / 4 stripe 5 positioned between the first dual-mode single-cavity unit 3 and the second dual-mode single-cavity unit 4. Both the first dual-mode single-cavity unit 3 and the second dual-mode single-cavity unit 4 are patch structures, and the patch structure is a perturbation patch structure etched with cross-slot lines.

[0037] The first dual-mode single-cavity unit 3 includes a first resonator 6 and a second resonator 7, and the second dual-mode single-cavity unit 4 includes a third resonator 8 and a fourth resonator 9.

[0038] like Figure 1 Preferably, the filter body is provided with a main coupling path and a cross coupling path. The main coupling path includes the source feed line 1 being coupled to the first resonator 6 and the second resonator 7 simultaneously. The first resonator 6 and the second resonator 7 are both coupled to the λg / 4 stripline 5. The λg / 4 stripline 5 is also coupled to the third resonator 8 and the fourth resonator 9 simultaneously. The third resonator 8 and the fourth resonator 9 are both coupled to the load feed line 2.

[0039] The cross-coupling path includes source feed line 1 coupled to λg / 4 stripe line 5, and λg / 4 stripe line 5 coupled to load feed line 2.

[0040] exist Figure 1 Solid lines represent the main coupling path, and dashed lines represent cross-coupling paths.

[0041] like Figure 2 As shown, the filter body also includes a layer metal plate 10, an intermediate dielectric plate 11 and a bottom metal plate 12. The upper metal plate 10 is also provided with SIW electric walls 13, which are arranged around the first dual-mode single-cavity unit 3 and the second dual-mode single-cavity unit 4 respectively.

[0042] The upper metal plate 10 and the lower metal plate 12 sandwich the intermediate medium plate 11.

[0043] Preferably, the source feed line 1 and the load feed line 2 include microstrip lines with an impedance of 50Ω.

[0044] Preferably, the λg / 4 stripe 5 has a zigzag folded structure.

[0045] To verify the performance of the aforementioned high-selectivity planar dual-cavity dual-mode patch filter (hereinafter referred to as the filter), the following experiment was conducted:

[0046] The filter parameters are as follows. The filter includes a dual-mode dual-cavity patch, a source feed line 1, a load feed line 2, a λg / 4 stripe line 5, and a SIW electric wall 13. The preferred dielectric substrate is Rogers 5880, with a relative permittivity of 2.2 and a thickness of 0.508 mm.

[0047] In this experiment, such as Figure 3 As shown, the overall size of the filter L =77.5 mm, W =40 mm; Width of source feeder 1 and load feeder 2 W 0 = 1.54 mm; the diameter of the metal through-hole of SIW electrode 13 is D =0.8 mm; the etched groove dimensions in the dual-mode patch are W 1 = 0.3 mm, L 1 = 24.35 mm L 2 = 22.00 mm; λ g / 4 The width of the line 5 is W 2 = 0.56 mm.

[0048] Figure 4 The simulation results for the above filter are presented. From the filter parameter curves, it can be seen that the center frequency is 2.4 GHz, the in-band insertion loss is 1.2 dB, the in-band reflection loss is approximately -20 dB, and the -3 dB bandwidth is 170 MHz (relative bandwidth 7.1%). The frequency locations of the four finite-frequency transmission zeros are approximately 2.03 GHz, 2.17 GHz, 2.70 GHz, and 2.85 GHz. The filter's S-parameter plot directly demonstrates its highly selective filtering characteristics.

[0049] Figure 5 This is an example of finite-frequency transmission zero-point modulation for the above filter. (By...) Figure 5 It can be seen that by regulating λ g The vector length of the 4-bar 5 is used to adjust the position of the finite frequency transmission zeros on both sides, thereby further improving the high selectivity of the above filter.

[0050] Figure 6 This is an example of an adjustable bandwidth filter. By adjusting λ... g The width of the / 4 bar 5 is used to adjust the coupling strength between the first dual-mode single-cavity unit 3 and the second dual-mode single-cavity unit 4, thereby controlling the passband bandwidth of the filter without changing the patch resonator, making the bandwidth controllable and adjustable. This further improves the selectivity of the filter.

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included within the scope of the present invention.

Claims

1. A high-selectivity planar dual-cavity dual-mode patch filter, comprising a source feed line (1), a load feed line (2), and a filter body, wherein one end of the filter body is connected to a source via the source feed line (1), and the other end is connected to a load via the load feed line (2), characterized in that, The filter body includes a first dual-mode single-cavity unit (3) and a second dual-mode single-cavity unit (4), with a λg / 4 stripe (5) between the first dual-mode single-cavity unit (3) and the second dual-mode single-cavity unit (4); both the first dual-mode single-cavity unit (3) and the second dual-mode single-cavity unit (4) are patch structures, and the patch structure includes a patch etched with a cross-slot line disturbance structure. The first dual-mode single-cavity unit (3) includes a first resonator (6) and a second resonator (7), and the second dual-mode single-cavity unit (4) includes a third resonator (8) and a fourth resonator (9). The filter body is provided with a main coupling path and a cross coupling path. The main coupling path includes the simultaneous coupling of the source feed line (1) with the first resonator (6) and the second resonator (7). The first resonator (6) and the second resonator (7) are both coupled with the λg / 4 strip (5). The λg / 4 strip (5) is also simultaneously coupled with the third resonator (8) and the fourth resonator (9). The third resonator (8) and the fourth resonator (9) are both coupled with the load feed line (2). The cross-coupling path includes a source feed line (1) coupled to a λg / 4 stripe line (5), and a λg / 4 stripe line (5) coupled to a load feed line (2). The λg / 4 strip (5) has a zigzag folded structure.

2. The high-selectivity planar dual-cavity dual-mode patch filter according to claim 1, characterized in that, The filter body also includes an upper metal plate (10), an intermediate dielectric plate (11) and a bottom metal plate (12). The upper metal plate (10) is also provided with SIW electric walls (13), which are arranged around the first dual-mode single-cavity unit (3) and the second dual-mode single-cavity unit (4), respectively. The upper metal plate (10) and the lower metal plate (12) sandwich the intermediate medium plate (11).

3. The high-selectivity planar dual-cavity dual-mode patch filter according to claim 1, characterized in that, Both the source feed (1) and the load feed (2) include microstrip lines with an impedance of 50Ω.

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