Coaxial cavity resonator based on microstrip plane structure

Abstract

The invention discloses a coaxial cavity resonator based on a microstrip plane structure, and belongs to the technical field of communication. The dielectric substrate is provided with a plurality of outer metallized via holes, and the plurality of outer metallized via holes are arranged to form a surrounding structure; an inner metalized via hole is formed in the surrounding structure; the upper surface of the dielectric substrate is not provided with a metal conductor, and the lower surface is provided with a metal conductor. The planar design of the coaxial cavity resonator is realized, and the coaxial cavity resonator has the advantages of simple structure, convenience in processing and high quality factor.

Description

Technical Field

[0001] This invention belongs to the field of communication technology and relates to a resonator, and more particularly to a coaxial cavity resonator based on a microstrip planar structure. Background Technology

[0002] In the field of modern communication technology, microwave communication systems are widely used in key scenarios such as satellite communication, 5G base stations, and radar detection due to their advantages such as high transmission rate and strong anti-interference capability. As a core passive component in microwave communication systems, the performance of filters directly determines the purity and efficiency of signal transmission. Filters mainly undertake the important functions of filtering effective signals and suppressing clutter interference. Therefore, there are stringent requirements for the quality factor (Q value), in-band insertion loss, size, and integration compatibility of filters.

[0003] In existing microwave communication systems, filters with planar structures are mainly implemented using microstrip resonators. These filters, with their planar design advantages, can be well integrated with printed circuit boards (PCBs) and are widely used in miniaturized communication devices with high requirements for size and integration. However, due to the inherent dielectric and radiation loss characteristics of the microstrip structure, they suffer from low quality factor and high in-band insertion loss. While filters constructed from coaxial cavity resonators offer advantages such as high quality factor and low in-band insertion loss, their larger size makes them inconvenient to connect to PCBs. For example, the paper "Capacitively loaded resonator for compact substrate integrated waveguide filters" proposes a resonator structure with a waveguide-loaded capacitor integrated on the substrate and applies it to filter design. Although this achieves a planar design of the coaxial cavity, it suffers from reduced Q value and increased passband insertion loss. Patent CN111446532B proposes a double-layer PCB structure, requiring screw fixation, which adds complexity to its fabrication.

[0004] In summary, both planar structure filters and coaxial cavity resonator filters in existing microwave communication systems have technical defects that make it difficult to balance performance, size, and integration compatibility. They cannot fully meet the application requirements of current microwave communication technology, which is developing towards higher precision, miniaturization, and higher integration. Therefore, developing a filter that combines high quality factor, low insertion loss, miniaturized structure, and good PCB integration has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] This invention provides a coaxial cavity resonator based on a microstrip planar structure to overcome the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a coaxial cavity resonator based on a microstrip planar structure, comprising a dielectric substrate; the dielectric substrate is provided with a plurality of external metallized vias penetrating its upper and lower surfaces, the plurality of external metallized vias being arranged in an enclosing structure; an internal metallized via is provided inside the enclosing structure; in this application, metallization in the metallized vias refers to plating a thin layer of metal conductor on the via wall; the upper surface of the dielectric substrate has no metal conductor, and the lower surface is covered with a metal conductor.

[0008] To optimize the above technical solution, the specific measures also include:

[0009] Furthermore, the external metallized via is a through hole with a uniform inner diameter.

[0010] Furthermore, the external metallized vias are arranged in a rectangular pattern and are evenly distributed.

[0011] Furthermore, the upper end opens onto the upper surface of the dielectric substrate, forming an open-circuit structure; the metal conductor inside the lower end is connected to the metal conductor on the lower surface of the dielectric substrate, forming a short-circuit structure.

[0012] Furthermore, the internal metallized via is located at the center of the surrounding structure.

[0013] Furthermore, the internal metallized via can be a through hole with a consistent inner diameter.

[0014] Furthermore, the internal metallized via can also be a stepped via, which is divided into an upper via and a lower via according to its inner diameter, with the inner diameter of the upper via being larger than that of the lower via.

[0015] Furthermore, a metal conductor is laid on the stepped surface between the lower and upper holes of the internal metallized via.

[0016] Furthermore, the lower and upper holes of the internal metallized via are of equal height.

[0017] Furthermore, the heights of the lower and upper holes of the internal metallized via are not equal.

[0018] The beneficial effects of this invention are as follows: This invention provides a coaxial cavity resonator based on a microstrip planar structure. The microstrip planar structure of the coaxial cavity resonator is realized based on SIW (substrate integrated waveguide). External metallized vias arranged around the dielectric substrate serve as the outer conductor of the coaxial structure, achieving a shielding effect. Due to the skin effect, the central internal metallized via serves as the inner conductor of the coaxial structure. This scheme can construct a λ / 4 resonator with a short-circuited termination. Furthermore, the internal metallized via can be a stepped via, and through upper and lower vias with different inner diameters, a coaxial structure with different characteristic impedances in the upper and lower parts can be achieved.

[0019] This invention's resonator achieves the function of a coaxial cavity resonator with a planar structure, capable of exciting its TEM (transverse electromagnetic mode) dominant mode. The resonant frequency in this operating mode is much lower than the resonant frequency of a substrate-integrated waveguide of the same size, giving the proposed microstrip coaxial resonator miniaturization and a high quality factor. Microwave devices such as filters can be easily connected to other components on a PCB via a microstrip connection using the resonator of this invention. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the coaxial cavity resonator in Example 2;

[0021] Figure 2 This is a schematic diagram of the coaxial cavity resonator from another angle in Embodiment 2;

[0022] Figure 3 This is a TEM mode electric field distribution diagram of the coaxial cavity resonator in Example 2;

[0023] The labels in the attached diagram are: 1. Dielectric substrate; 2. External metallized via; 3. Internal metallized via. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0025] Example 1

[0026] This embodiment provides a coaxial cavity resonator based on a microstrip planar structure, including a dielectric substrate. The dielectric substrate has a plurality of external metallized vias penetrating its upper and lower surfaces, arranged in an enclosing structure. Internal metallized vias are disposed inside the enclosing structure. In this application, metallization in the metallized vias refers to depositing a thin layer of metal conductor, such as copper or silver, on the via wall. The upper surface of the dielectric substrate has no metal conductor, while the lower surface has a metal conductor, such as copper or silver.

[0027] The external metallized vias are through-holes with a uniform inner diameter. Several external metallized vias are arranged in a rectangular pattern and evenly distributed. The upper end of the internal metallized via opens onto the upper surface of the dielectric substrate, forming an open-circuit structure; the metal conductor inside the lower end connects to the metal conductor on the lower surface of the dielectric substrate, forming a short-circuit structure. The internal metallized via is located at the center of the surrounding structure.

[0028] In this embodiment, the inner metallized vias are through holes with a uniform inner diameter. For example, if the dielectric constant of the dielectric substrate is 2.2 and the resonant frequency is 3GHz, the thickness is approximately 1.6cm. If the frequency is lower, the dielectric substrate will be thicker, but this may have poor engineering adaptability. Alternatively, if the resonant frequency is above tens of GHz, a dielectric substrate of appropriate thickness can be selected, but the diameter of the outer metallized vias must be less than 0.2mm.

[0029] The principle of the coaxial cavity resonator in this embodiment is as follows: the outer metallized vias distributed around the dielectric substrate serve as the outer conductors of the coaxial structure, achieving a shielding effect. Due to the skin effect, the inner metallized vias in the middle serve as the inner conductors of the coaxial structure.

[0030] Example 2

[0031] This embodiment provides a coaxial cavity resonator based on a microstrip planar structure, including a dielectric substrate 1. The dielectric substrate 1 has a plurality of external metallized vias 2 penetrating its upper and lower surfaces, arranged in an enclosing structure. An internal metallized via 3 is disposed inside the enclosing structure. In this application, metallization in the metallized vias refers to depositing a thin layer of metal conductor, such as copper or silver, on the via wall. The upper surface of the dielectric substrate 1 has no metal conductor, while the lower surface has a metal conductor, such as copper or silver.

[0032] The external metallized vias 2 are through holes with a uniform inner diameter. Several external metallized vias 2 are arranged in a rectangular shape and evenly distributed. The upper end of the internal metallized via 3 opens onto the upper surface of the dielectric substrate 1, forming an open-circuit structure; the metal conductor inside the lower end connects to the metal conductor on the lower surface of the dielectric substrate 1, forming a short-circuit structure. The internal metallized via 3 is located at the center of the surrounding structure.

[0033] In this embodiment, the internal metallized via 3 is a stepped via, divided into an upper via and a lower via according to its inner diameter, with the inner diameter of the upper via being larger than that of the lower via. The heights of the lower and upper vias of the internal metallized via 3 may be equal or unequal. A metal conductor, such as copper or silver, is laid on the stepped surface between the lower and upper vias of the internal metallized via 3.

[0034] The principle of the coaxial cavity resonator in this embodiment is as follows: the outer metallized vias 2 distributed around the dielectric substrate 1 serve as the outer conductors of the coaxial structure, achieving a shielding effect. Due to the skin effect, the stepped-hole inner metallized vias 3 serve as the inner conductors of the coaxial structure. Because the inner diameters of the upper and lower holes of the coaxial inner conductor are different, the characteristic impedances of the upper and lower parts of the coaxial structure are different. The stepped-hole inner metallized vias 3 are connected to the metal conductor on the lower surface of the dielectric substrate 1, achieving a short circuit at the termination. By setting a reasonable inner diameter and height of the stepped-hole inner metallized vias 3, a λ / 4 short-circuited SIR resonator is constructed. Preferably, when the heights of the upper and lower holes of the stepped-hole inner metallized vias 3 are equal, the resonator with the smallest size can be obtained.

[0035] Figure 3 This is a TEM mode electric field distribution diagram of the substrate-integrated coaxial resonator in this embodiment. From... Figure 3 It can be seen that the electric field distribution of the TEM (transverse electromagnetic mode) is the largest at the top of the metallized stepped aperture. Since the frequency of the TEM mode is much smaller than the resonant frequency of the substrate integrated waveguide of the same size, the coaxial resonant cavity of the substrate integrated waveguide has miniaturization characteristics, and the miniaturized design of filters can be carried out using this coaxial resonant cavity.

[0036] In this invention, unless otherwise stated, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0037] It should be noted that the terms such as "upper", "lower", "left", "right", "front", and "back" used in the invention are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0038] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coaxial cavity resonator based on a microstrip planar structure, characterized in that: Including dielectric substrate; The dielectric substrate is provided with a plurality of external metallized vias, which are arranged in an enclosing structure. The enclosing structure is provided with internal metallized vias. The upper surface of the dielectric substrate has no metal conductor, while the lower surface is covered with a metal conductor.

2. The coaxial cavity resonator based on a microstrip planar structure according to claim 1, characterized in that: The external metallized vias are through holes with a consistent inner diameter.

3. The coaxial cavity resonator based on a microstrip planar structure according to claim 2, characterized in that: Several of the external metallized vias are arranged in a rectangular pattern and are evenly distributed.

4. The coaxial cavity resonator based on a microstrip planar structure according to claim 2, characterized in that: The upper end of the internal metallized via opens onto the upper surface of the dielectric substrate, forming an open circuit structure; the metal conductor inside the lower end is connected to the metal conductor on the lower surface of the dielectric substrate, forming a short circuit structure.

5. The coaxial cavity resonator based on a microstrip planar structure according to claim 4, characterized in that: The internal metallized via is located at the center of the surrounding structure.

6. The coaxial cavity resonator based on a microstrip planar structure according to claim 4, characterized in that: The internal metallized vias are through holes with a uniform inner diameter.

7. The coaxial cavity resonator based on a microstrip planar structure according to claim 4, characterized in that: The internal metallized via is a stepped via, divided into an upper via and a lower via according to its inner diameter, with the inner diameter of the upper via being larger than that of the lower via.

8. The coaxial cavity resonator based on a microstrip planar structure according to claim 7, characterized in that: A metal conductor is laid on the stepped surface between the lower and upper holes of the internal metallized via.

9. The coaxial cavity resonator based on a microstrip planar structure according to claim 7, characterized in that: The lower and upper holes of the internal metallized via are at the same height.

10. The coaxial cavity resonator based on a microstrip planar structure according to claim 7, characterized in that: The heights of the lower and upper holes of the internal metallized via are not equal.

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