A dual-band coupled filter based on hemispherical resonator

Abstract

This invention discloses a dual-passband coupled filter based on a hemispherical resonator, comprising: a first hemispherical resonator, a second hemispherical resonator, a common metal bottom surface, a first coaxial feed connector, a second coaxial feed connector, a third coaxial feed connector, and a fourth coaxial feed connector. The first and second hemispherical resonators are placed back-to-back at their maximum diameter. The common metal bottom surface is disposed between the first and second hemispherical resonators and has a first through-hole, a second through-hole, a third through-hole, and a fourth through-hole. The first and second coaxial feed connectors are both disposed at the lower end of the first hemispherical resonator along a direction parallel to the common metal bottom surface, and the third and fourth coaxial feed connectors are both disposed at the lower end of the second hemispherical resonator along a direction parallel to the common metal bottom surface.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a dual-passband coupled filter based on a hemispherical resonant cavity. Background Technology

[0002] In recent years, wireless communication technology has developed rapidly in industrial and consumer electronics sectors, leading to a large demand for various high-performance microwave devices. Couplers have a wide range of applications in radio frequency (RF) front-ends, such as mixers, power amplifiers, phase shifters, modulators, and antenna array feed networks, and can be used for signal isolation, separation, and mixing. Additionally, filters are also crucial components in RF front-ends, primarily functioning to selectively filter transmitted and received frequency signals, eliminating unwanted frequencies to ensure the accuracy of transmitted and received signals in traditional RF systems. Typically, these two devices are designed independently and then cascaded to achieve the coupling and filtering function. This design occupies a large circuit volume, and inter-stage mismatch also degrades circuit performance. Against this backdrop, the synergistic integration design of filters and couplers has attracted increasing attention from researchers.

[0003] In today's rapidly developing communication technology, circuits in the communication field often require a high quality factor (high Q) to achieve low loss and high power in the communication process. However, existing microstrip coupled filters suffer from low Q values ​​and power margins, while cavity coupled filters offer high Q values ​​but are large in size. In practice, it has been found that spherical cavities exhibit the highest quality factor among all possible cavity geometries due to their largest volume-to-surface-area ratio. Furthermore, the geometry of a hemispherical cavity is half that of a symmetrical spherical cavity, and their resonant modes and corresponding electromagnetic field distributions are similar. Therefore, proposing a hemispherical resonant cavity coupled filter based on a spherical resonant cavity is feasible.

[0004] Furthermore, high-performance dual-band and multi-band waveguide filter devices, due to their powerful multi-operating passband capabilities, significantly reduce the overhead of wireless modules and are widely used in wireless communication systems. Therefore, developing a high-quality, multi-passband filter is extremely important. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a dual-passband coupled filter based on a hemispherical resonant cavity.

[0006] Technical Solution: To solve the above-mentioned technical problems, this invention proposes a dual-passband coupling filter based on a hemispherical resonant cavity. The filter structure includes a first hemispherical resonant cavity (100), a second hemispherical resonant cavity (200), and a common circular metal bottom surface (300) disposed between the first hemispherical resonant cavity (100) and the second hemispherical resonant cavity (200) to form a spherical resonant cavity. The first hemispherical resonant cavity (100) is disposed on the upper part of the common circular metal bottom surface (300), and the second hemispherical resonant cavity (200) is disposed on the lower part of the common circular metal bottom surface (300). The common circular metal bottom surface (300) is provided with through holes distributed on two mutually perpendicular diameters. Furthermore, the spherical resonant cavity is provided with an output port and an input port on opposite sides, and the output port and the input port are located on both sides of the spherical resonant cavity.

[0007] Preferably, the through hole includes two first through hole portions (310), two second through holes (320), two third through holes (330), and two fourth through holes (340). The two first through holes (310) and the two third through holes (330) are symmetrically arranged on the first diameter of the common circular metal bottom surface (300), and the two second through holes (320) and the two fourth through holes (340) are symmetrically arranged on the second diameter of the common circular metal bottom surface (300). The first diameter and the second diameter are perpendicular.

[0008] The two first through holes (310) and the two third through holes (330) are located on both sides of the center of the common circular metal bottom surface (300); the two second through holes (320) and the two fourth through holes (340) are located on both sides of the center of the common circular metal bottom surface (300), and the distance between the two third through holes (330) and the center of the common circular metal bottom surface (300) is less than the distance between the two first through holes (310) and the center of the common circular metal bottom surface (300); the distance between the two fourth through holes (340) and the center of the common circular metal bottom surface (300) is less than the distance between the two second through holes (320) and the center of the common circular metal bottom surface (300).

[0009] Preferably, the first through hole 310, the two second through holes 320, the two third through holes 330, and the two fourth through holes 340 are all rectangular through holes.

[0010] Preferably, the input ports include a first input port (510) and a second input port (520);

[0011] The first input port (510) includes a coaxial probe and a first coaxial feed connector (410). The first coaxial probe is inserted into the first hemispherical resonator (100) along a direction parallel to the common circular metal bottom surface (300) and is located at the lower part of the first hemispherical resonator (100). The first coaxial feed connector (410) is disposed on the outer end of the first coaxial probe.

[0012] The second input port 520 includes a second coaxial probe and a second coaxial power connector 420. The second coaxial probe is inserted into the first hemispherical resonator (100) along a direction parallel to the common circular metal bottom surface (300) and is located at the lower part of the first hemispherical resonator (100). The second coaxial power connector (420) is disposed on the outer end of the second coaxial probe.

[0013] The first coaxial probe is parallel to the common circular metal bottom surface (300) and the second coaxial probe is perpendicular to the common circular metal bottom surface (300); the projection of the first coaxial probe on the common circular metal bottom surface (300) is located on the first diameter and the projection of the second coaxial probe on the common circular metal bottom surface (300) is located on the second diameter.

[0014] Preferably, the output ports include a first output port (610) and a second output port (620);

[0015] The first output port (610) includes a third coaxial probe and a third coaxial feed connector (430); the third coaxial probe is inserted into the second hemispherical resonator (200) along a direction parallel to the common metal bottom surface (300) and is located on the upper part of the second hemispherical resonator (200); the third coaxial feed connector (430) is disposed on the outer end of the third coaxial probe.

[0016] The second output port (620) includes a fourth coaxial probe and a fourth coaxial feed connector (440); the fourth coaxial probe is inserted into the second hemispherical resonator (200) along a direction parallel to the common metal bottom surface (300) and is located on the upper part of the second hemispherical resonator (200); the fourth coaxial feed connector (440) is disposed on the outer end of the fourth coaxial probe; the projections of the third and fourth coaxial probes on the common circular metal bottom surface (300) are symmetrical about the projection of the first coaxial probe on the common circular metal bottom surface (300); and the third and fourth coaxial probes are located on opposite sides of the spherical resonant cavity from the first and second coaxial probes.

[0017] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0018] To address the issues of low quality factor and excessive size in existing dual-frequency and multi-frequency coupled filters, a dual-passband coupled filter based on a hemispherical cavity is proposed. This coupled filter features a simple design, excellent performance, a higher quality factor than existing cavity coupled filters, and a significantly reduced size. Verification has shown that this coupled filter can be mass-produced using 3D printing technology, offering advantages such as lighter weight, smaller size, and lower cost compared to dual-passband coupled filters manufactured using traditional processes. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the internal structure of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the four port planar positions according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the planar positions of the four coupling through slots in an embodiment of the present invention;

[0024] Figure 5 This is a simulation and test diagram of the S-parameters of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention;

[0025] Figure 6 This is a port phase simulation and test diagram of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, rather than to describe a specific order.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] like Figures 1 to 4 As shown, this embodiment of the invention discloses a dual-passband coupled filter based on a hemispherical resonant cavity, the filter comprising:

[0030] A first hemispherical resonant cavity 100 and a second hemispherical resonant cavity 200 are placed back-to-back with the first hemispherical resonant cavity 100 at its maximum diameter. A common circular metal bottom surface 300 is disposed between the first hemispherical resonant cavity 100 and the second hemispherical resonant cavity 200. The first hemispherical resonant cavity 100 is disposed on the upper part of the common circular metal bottom surface 300, and the second hemispherical resonant cavity 200 is disposed on the lower part of the common circular metal bottom surface 300. The first hemispherical resonant cavity 100, the second hemispherical resonant cavity 200 and the common circular metal bottom surface 300 constitute a complete spherical resonant cavity.

[0031] A common circular metal bottom surface 300 is provided with two first through holes 310, two second through holes 320, two third through holes 330, and two fourth through holes 340. The two first through holes 310 and the two third through holes 330 are symmetrically arranged on a first diameter of the common circular metal bottom surface 300, and the two second through holes 320 and the two fourth through holes 340 are symmetrically arranged on a second diameter of the common circular metal bottom surface 300. The first diameter and the second diameter are perpendicular. The two through holes 320 and the two fourth through holes 340 are respectively located on both sides of the center of the common circular metal bottom surface 300. Furthermore, the distance between the two third through holes 330 and the center of the common circular metal bottom surface 300 is less than the distance between the two first through holes 310 and the center of the common circular metal bottom surface 300; the distance between the two fourth through holes 340 and the center of the common circular metal bottom surface 300 is less than the distance between the two second through holes 320 and the center of the common circular metal bottom surface 300.

[0032] The first coaxial probe is inserted into the first hemispherical resonator 100 along a direction parallel to the common circular metal bottom surface 300 and is located at the lower part of the first hemispherical resonator 100. The first coaxial power supply connector 410 is disposed on the outer end of the first coaxial probe. The coaxial probe and the first coaxial power supply connector 410 constitute the first input port 510.

[0033] The second coaxial probe is inserted into the first hemispherical resonator 100 along a direction parallel to the common circular metal bottom surface 300 and is located at the lower part of the first hemispherical resonator 100. The second coaxial feed connector 420 is disposed on the outer end of the second coaxial probe. The second coaxial probe and the second coaxial feed connector 420 constitute the second input port 520. The first coaxial probe is perpendicular to the common circular metal bottom surface 300 along a direction parallel to the common circular metal bottom surface 300. The projection of the first coaxial probe on the common circular metal bottom surface 300 is located on the first diameter, and the projection of the second coaxial probe on the common circular metal bottom surface 300 is located on the second diameter.

[0034] The third coaxial probe is inserted into the second hemispherical resonator 200 along a direction parallel to the common metal bottom surface 300 and is located on the upper part of the second hemispherical resonator 200. The third coaxial feed connector 430 is disposed on the outer end of the third coaxial probe. The third coaxial probe and the third coaxial feed connector 430 constitute the first output port 610.

[0035] The fourth coaxial probe is inserted into the second hemispherical resonator 200 along a direction parallel to the common metal bottom surface 300 and is located on the upper part of the second hemispherical resonator 200. The fourth coaxial feed connector 440 is disposed on the outer end of the fourth coaxial probe. The fourth coaxial probe and the fourth coaxial feed connector 440 constitute the first output port 620. The projections of the third and fourth coaxial probes on the common circular metal bottom surface (300) are symmetrical about the projection of the first coaxial probe on the common circular metal bottom surface (300). Furthermore, the third and fourth coaxial probes are located on opposite sides of the spherical resonator cavity to the first and second coaxial probes.

[0036] In this embodiment of the invention, the first hemispherical resonant cavity and the second hemispherical resonant cavity are each half of a symmetrical spherical resonant cavity. It can be understood that the two constitute a complete spherical resonant cavity. Furthermore, the electromagnetic field distributions corresponding to the hemispherical resonant cavity and the spherical resonant cavity are similar. This enables the dual-passband coupling filter based on the hemispherical resonant cavity in this embodiment of the invention to obtain high-quality coefficients corresponding to those of the spherical resonant cavity during operation.

[0037] In this embodiment of the invention, a common metal bottom surface is disposed between the first hemispherical resonant cavity and the second hemispherical resonant cavity. The common circular metal bottom surface is provided with two first through holes, two second through holes, two third through holes, and two fourth through holes, realizing resonant coupling between the first and second hemispherical resonant cavities. When a signal is applied to the first input terminal, the first and second through holes equally distribute the energy to the first and second output ports, achieving a 0° phase difference and a second-order filtering response. When a signal is applied to the second input terminal, the third and fourth through holes equally distribute the energy to the first and second output ports, achieving a 180° phase difference and a second-order filtering response, thereby realizing a dual-passband coupled filtering function.

[0038] In this embodiment of the invention, since the coupling filter is a four-port network, and the size of the four rectangular waveguide ports is too large and cannot be reasonably arranged at the edge of the maximum diameter of the hemispherical resonator, the dual-passband coupling filter based on the hemispherical resonator selects coaxial probe excitation. By setting the input and output ports at appropriate positions in the hemispherical resonator and adjusting the insertion length of the metal probe into the hemispherical resonator, good impedance matching between the port and the resonator is achieved, so that most of the energy is transmitted into the waveguide.

[0039] In this embodiment of the invention, as shown in Figure 2, the center line of the second coaxial power supply connector 420 is coplanar with and perpendicular to the center line of the first coaxial power supply connector 410. Because the TE selected in this embodiment... 101 TM 211 The inherent electric field distribution of the mode, when a signal is applied to the first input port 510, excites TE. 101A TM 211A In this mode, the signal cannot be transmitted to the second input port 520, and the first input port 510 and the second input port 520 are naturally isolated. Similarly, when a signal is applied to the second input port 520, it triggers a TE. 101A TM 211A The degenerate TE model 101B TM 211B The signal cannot be transmitted to the first input port 510, and good isolation is achieved between the two input ports.

[0040] In this embodiment of the invention, as shown in Figure 2, the third coaxial feed connector 430 is located on the side of the first coaxial feed connector 410 away from the second coaxial feed connector 420, and the fourth coaxial feed connector 440 is located on the side of the third coaxial feed connector 430 away from the first coaxial feed connector 410, symmetrically distributed with the third coaxial feed connector 430 about the center line of the first coaxial feed connector 410. By reasonably setting the positions of the first output port 610 and the second output port 620, when a signal is applied to the first input port 510, the two output ports can receive signals of equal amplitude and in phase, while when a signal is applied to the second input port 520, the two output ports can receive signals of equal amplitude and out of phase, thus realizing the function of a second-order filter 180° coupler.

[0041] In some specific embodiments of the present invention, as shown in Figure 4, the first through-hole 310, the second through-hole 320, the third through-hole 330, and the fourth through-hole 340 are rectangular. These four through-holes control the coupling between the two hemispherical resonant cavities. The rectangular design facilitates energy transmission and reduces energy loss, resulting in superior performance of the dual-passband coupled filter based on the hemispherical resonant cavity.

[0042] In some specific embodiments of the present invention, as shown in FIG4, two third through holes 330 are disposed on the side of the first through hole away from the edge of the common metal bottom surface 300, and two fourth through holes are disposed on the side of the second through hole away from the edge of the common metal bottom surface. Two pairs of degenerate modes TE 101 TM 211 The electric field distribution is similar, but the location of the strongest electric field differs. In contrast, TE 101 The location with the strongest electric field is closer to the center of the circle, therefore, TM 211 The mode primarily transmits through the first and second vias, forming a low-frequency passband, while TE... 101 The mode is mainly transmitted through the third and fourth through holes near the center, forming a high-frequency passband. By setting four through holes, the coupling control inside the two hemispherical resonator cavities is relatively independent.

[0043] The following are some key dimensional parameters of this dual-passband coupled filter based on a hemispherical resonant cavity for manufacturing reference. The common metal base can be a circular plate with a thickness of 1mm and a radius r0 of 16mm. For example... Figure 3As shown in Figure 4, the insertion depths t1, t2, t3, and t4 of the metal probes in the four coaxial feed connectors are all 9.5 mm. The first rectangular through-hole has a length l1 of 8.5 mm, a width w1 of 2.0 mm, and a distance d1 of 8.0 mm from the center point of the common metal bottom surface. The second rectangular through-hole has a length l2 of 8.5 mm, a width w2 of 2.0 mm, and a distance d2 of 7.9 mm from the center point of the common metal bottom surface. The third rectangular through-hole has a length l3 of 5.1 mm, a width w3 of 2.0 mm, and a distance d3 of 2.8 mm from the center point of the common metal bottom surface. The fourth rectangular through-hole has a length l4 of 5.6 mm, a width w4 of 2.0 mm, and a distance d4 of 3.5 mm from the center point of the common metal bottom surface.

[0044] like Figure 5 The figure shows the S-parameter simulation and test results of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention, wherein S... 11 S represents the reflection coefficient of the first input port. 31 S represents the transmission coefficient from the first input port to the first output port. 41 This represents the transmission coefficient from the first input port to the second output port. The figure shows that the center frequencies of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention are 11.61 GHz and 13.29 GHz, corresponding to a 3 dB bandwidth frequency of 250 MHz. The measured minimum in-band insertion loss is approximately 4.07 dB and 3.60 dB, and the maximum return loss at the input port is 19 dB and 25 dB, respectively.

[0045] like Figure 6 The figure shows the phase simulation and test results of a dual-passband coupled filter based on a hemispherical resonant cavity according to an embodiment of the present invention. The figure shows that when the signal is input from the first input port, the phase difference between the first and second output ports is approximately 0°; when the signal is input from the second input port, the corresponding phase difference between the first and second output ports is approximately 180°, achieving the phase characteristics of a 180° coupler.

[0046] Finally, it should be noted that the dual-passband coupling filter based on a hemispherical resonant cavity disclosed in the embodiments of the present invention is only a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hemispherical resonator based dual-passband coupled filter characterized by, The filter structure includes a first hemispherical resonant cavity (100), a second hemispherical resonant cavity (200), and a common circular metal bottom surface (300) disposed between the first hemispherical resonant cavity (100) and the second hemispherical resonant cavity (200) to form a spherical resonant cavity; the first hemispherical resonant cavity (100) is disposed on the upper part of the common circular metal bottom surface (300), and the second hemispherical resonant cavity (200) is disposed on the lower part of the common circular metal bottom surface (300); the common circular metal bottom surface (300) is provided with through holes distributed on two mutually perpendicular diameters; and the spherical resonant cavity is provided with an output port and an input port on opposite sides above and below, and the output port and the input port are located on both sides of the spherical resonant cavity; The through holes include two first through holes (310), two second through holes (320), two third through holes (330), and two fourth through holes (340). The two first through holes (310) and the two third through holes (330) are symmetrically arranged on the first diameter of the common circular metal bottom surface (300), and the two second through holes (320) and the two fourth through holes (340) are symmetrically arranged on the second diameter of the common circular metal bottom surface (300). The first diameter and the second diameter are perpendicular. The two first through holes (310) and the two third through holes (330) are located on both sides of the center of the common circular metal bottom surface (300); the two second through holes (320) and the two fourth through holes (340) are located on both sides of the center of the common circular metal bottom surface (300), and the distance between the two third through holes (330) and the center of the common circular metal bottom surface (300) is less than the distance between the two first through holes (310) and the center of the common circular metal bottom surface (300); the distance between the two fourth through holes (340) and the center of the common circular metal bottom surface (300) is less than the distance between the two second through holes (320) and the center of the common circular metal bottom surface (300).

2. The dual-passband coupled filter based on a hemispherical resonant cavity according to claim 1, characterized in that, The two first through holes (310), two second through holes (320), two third through holes (330), and two fourth through holes (340) are rectangular through holes.

3. A dual-passband coupled filter based on a hemispherical resonant cavity according to claim 1 or 2, characterized in that, The input ports include a first input port (510) and a second input port (520); The first input port (510) includes a coaxial probe and a first coaxial feed connector (410). The first coaxial probe is inserted into the first hemispherical resonant cavity (100) along a direction parallel to the common circular metal bottom surface (300) and is located at the lower part of the first hemispherical resonant cavity (100). The first coaxial feed connector (410) is disposed on the outer end of the first coaxial probe. The second input port (520) includes a second coaxial probe and a second coaxial feed connector (420). The second coaxial probe is inserted into the first hemispherical resonant cavity (100) along a direction parallel to the common circular metal bottom surface (300) and is located at the lower part of the first hemispherical resonant cavity (100). The second coaxial feed connector (420) is disposed on the outer end of the second coaxial probe. The first coaxial probe is parallel to the common circular metal bottom surface (300) and the second coaxial probe is perpendicular to the common circular metal bottom surface (300); the projection of the first coaxial probe on the common circular metal bottom surface (300) is located on the first diameter and the projection of the second coaxial probe on the common circular metal bottom surface (300) is located on the second diameter.

4. A dual-passband coupled filter based on a hemispherical resonant cavity according to claim 3, characterized in that, The output ports include a first output port (610) and a second output port (620); The first output port (610) includes a third coaxial probe and a third coaxial feed connector (430); the third coaxial probe is inserted into the second hemispherical resonant cavity (200) along a direction parallel to the common circular metal bottom surface (300) and is located on the upper part of the second hemispherical resonant cavity (200); the third coaxial feed connector (430) is disposed on the outer end of the third coaxial probe. The second output port (620) includes a fourth coaxial probe and a fourth coaxial feed connector (440); the fourth coaxial probe is inserted into the second hemispherical resonant cavity (200) along a direction parallel to the common circular metal bottom surface (300) and is located on the upper part of the second hemispherical resonant cavity (200); the fourth coaxial feed connector (440) is disposed on the outer end of the fourth coaxial probe; the projections of the third and fourth coaxial probes on the common circular metal bottom surface (300) are symmetrical about the projection of the first coaxial probe on the common circular metal bottom surface (300); and the third and fourth coaxial probes are opposite to the first and second coaxial probes and are located on both sides of the spherical resonant cavity.

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