Resonant cavity coupled antenna for microwave heating

Abstract

The utility model relates to an antenna, belongs to the technical field of microwave heating, and particularly discloses a resonant cavity coupling antenna for microwave heating, which comprises an antenna body, a coaxial waveguide and an air radio frequency connector, the upper end of the antenna body is connected with the coaxial waveguide, and the upper end of the coaxial waveguide is connected with the air radio frequency connector. A metal fixing base used for fixing the antenna is fixedly arranged between the antenna body and the coaxial waveguide, the coaxial waveguide is composed of an air coaxial waveguide with air as a medium on the upper half portion and a medium coaxial waveguide with an insulator as a medium on the lower half portion, and the antenna body comprises an antenna radiation arm, an antenna balance arm and an antenna extension arm. The utility model has the characteristics of simple structure, simple processing, assembling and mounting processes, high power capacity, high heat exchange efficiency, high microwave transmission efficiency and the like, and is suitable for microwave heating.

Description

TECHNICAL FIELD

[0001] The utility model relates to an antenna and belongs to the technical field of microwave heating, in particular to a resonant cavity coupling antenna for microwave heating. BACKGROUND

[0002] The antenna in a microwave oven is used to guide and distribute microwave energy to ensure that the microwave can be uniformly radiated to food, so as to achieve an ideal cooking effect. In a traditional high-frequency microwave oven, the antenna generally adopts a hole coupling mode to couple the microwave energy into the oven cavity. Since the penetration of low-frequency microwaves is more conducive to uniform heating of food, and as people's requirements for food cooking continue to improve, large-space and high-power low-frequency microwave cooking equipment has gradually emerged. However, in a low-frequency microwave oven, if a traditional coupling antenna is used, there are many problems, such as the need for a large resonant cavity hole coupling size, which affects the appearance and is prone to surface contamination, thereby causing a decrease in microwave coupling efficiency and a high requirement for the installation mode. Currently, some microwave ovens adopt a structure in which an antenna connected with a coaxial connector is directly inserted into a rectangular waveguide box, and the waveguide box is connected with the cavity. However, this structure cannot effectively suppress microwave power reflection, has a low heat exchange efficiency, and has a small power capacity, thereby causing a low microwave transmission efficiency. SUMMARY

[0003] To solve the above problems in the prior art, the utility model provides a resonant cavity coupling antenna for microwave heating, which solves the problems of low heat exchange efficiency and small power capacity, thereby improving the microwave transmission efficiency.

[0004] To achieve the above object, the utility model adopts the following technical scheme: a resonant cavity coupling antenna for microwave heating, comprising an antenna body, a coaxial waveguide, and an air radio frequency connector, the coaxial waveguide is fixedly connected with the air radio frequency connector at the upper end of the antenna body; the coaxial waveguide comprises an inner conductor and a tubular outer conductor concentric with the inner conductor, and a medium between the inner conductor and the outer conductor; the coaxial waveguide comprises an air coaxial waveguide with air as the medium in the upper half and a dielectric coaxial waveguide with an insulator as the medium in the lower half, and the insulator medium of the dielectric coaxial waveguide is tubular and fixedly arranged between the inner conductor and the outer conductor; the inner conductor is fixedly connected with the antenna body at the lower end.

[0005] As a limitation of the utility model, a metal fixing base for fixing the antenna is fixed between the antenna body and the coaxial waveguide, a center hole is formed in the metal fixing base, the inner conductor passes through the center hole and is connected with the antenna body below the metal base, and the outer conductor is fixedly arranged on the metal base.

[0006] As the limitation of the utility model: the antenna body includes antenna radiation arm, antenna balance arm and antenna extension arm, the antenna radiation arm is parallel to the metal fixed base, one end of the antenna radiation arm is open radiation end, the other end is connected with the antenna balance arm in vertical direction, the upper end of the antenna balance arm is connected with the metal fixed base; the antenna extension arm is vertically arranged, one end of the antenna extension arm is connected with the inner conductor, the other end is connected with the antenna radiation arm.

[0007] As the limitation of the utility model: the diameter of the center hole is smaller than the outer diameter of the insulator medium, a plurality of screw holes are arranged on the metal fixed base for fixing the metal fixed base on the cavity.

[0008] As the limitation of the utility model: the inner conductor and the antenna extension arm are integrated structure, the antenna radiation arm and the antenna balance arm are integrated structure, the antenna radiation arm and the antenna balance arm are long strip type; the antenna balance arm and the metal fixed base, the antenna extension arm and the antenna radiation arm are all connected by screws.

[0009] As the limitation of the utility model: the outer surface of the outer conductor is provided with fin structure.

[0010] As the limitation of the utility model: the inner conductor and the insulator medium, the insulator medium and the inner surface of the outer conductor are all provided with metal plating film.

[0011] As the limitation of the utility model: the inner conductor, the outer conductor and the antenna body are all made of copper material.

[0012] Compared with the prior art, the utility model has the beneficial effects that:

[0013] (1) the utility model adopts the structure that the antenna body is connected with the coaxial waveguide, and the coaxial waveguide is connected with the air radio frequency connector for inputting microwave, the coaxial waveguide is arranged as the common structure of air coaxial waveguide and dielectric coaxial waveguide, which is different from the traditional method of using only air as medium, and the insulator is introduced as medium, so that the heat exchange efficiency of the inner and outer spaces is improved, and the problem of low power capacity when only using insulator medium is overcome, and the microwave transmission efficiency is improved;

[0014] (2) the air coaxial waveguide, the dielectric coaxial waveguide and the metal fixed base are arranged in sequence to form the stepped impedance transformation structure, which effectively reduces the antenna reflection, improves the antenna working bandwidth and power capacity; the fin structure is arranged on the outer surface of the outer conductor, the contact area of the coaxial waveguide body and air is increased, the heat exchange efficiency is improved, and the stable working time of the overall structure under high power microwave input is improved; the metal plating film is filled in the gap between the inner conductor and the insulator medium, and the gap between the insulator medium and the inner surface of the outer conductor, so that the heat exchange efficiency is further improved;

[0015] (3) The utility model discloses a cavity side wall or top opening is inserted to feed in the microwave, replaces the antenna of traditional aperture coupling mode, and the metal fixed base that is provided simultaneously can install the antenna to the opening and can be fixed with screw directly, relative to the installation on rectangular aperture, it is not special to the chamfer of installation wall, the form of hole and so on, and the installation process is simple.

[0016] (4) The utility model discloses antenna body and metal fixed base adopt the design of screwing mode swing connection, inner conductor and antenna extension arm integral structure, antenna radiation arm and antenna balance arm are integral structure, can simplify processing technology, assembly process, reduce manufacturing cost, and the diameter of metal fixed base center hole is less than the outer diameter of insulator medium, to fix insulator medium, simplifies the installation process setting, and also can realize impedance matching.

[0017] Summarized above, the utility model discloses simple structure, processing and simple assembly, low cost, improve power capacity, heat exchange efficiency, microwave transmission efficiency etc. simultaneously, is applicable to microwave heating. BRIEF DESCRIPTION OF DRAWINGS

[0018] The utility model will be described in further detail below in combination with the drawings and specific embodiment.

[0019] Fig. 1 It is the three-dimensional structure schematic diagram of the utility model embodiment;

[0020] Fig. 2 It is the internal structure schematic diagram of the utility model embodiment;

[0021] Fig. 3 It is the antenna standing wave diagram in the heating cavity of the utility model embodiment.

[0022] In the drawing: 1-antenna body, 11-antenna radiation arm, 12-antenna balance arm, 13-antenna extension arm, 2-coaxial waveguide, 21-inner conductor, 22-outer conductor, 23-insulator medium, 24-fin structure, 3-air radio frequency connector, 4-metal fixed base, 41-center hole. DETAILED DESCRIPTION

[0023] The preferred embodiment of the utility model will be described below in combination with the drawings. It should be understood that the microwave heating resonant cavity coupling antenna described here is a preferred embodiment, which is used to illustrate and explain the utility model, and does not constitute a limitation on the utility model.

[0024] The directional terms or positional relationships used in this utility model, such as "up," "down," "left," and "right," are based on the positional relationships in the accompanying drawings of this utility model. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component must have a specific orientation, or that it must be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the content protected by this utility model. Example

[0025] This implementation example Figs. 1-3 As shown, a resonant cavity coupled antenna for microwave heating includes an antenna body 1, a coaxial waveguide 2, and an air RF connector 3. The upper end of the antenna body 1 is connected to the coaxial waveguide 2, and the upper end of the coaxial waveguide 2 is connected to the air RF connector 3. The air RF connector 3 is connected to a microwave source to realize the feeding of radio frequency microwave signals. A metal fixing base 4 for fixing the antenna is fixed between the antenna body 1 and the coaxial waveguide 2.

[0026] like Fig. 2 As shown, the coaxial waveguide 2 consists of a cylindrical inner conductor 21 and a tubular outer conductor 22 concentric with the inner conductor 21. Both the inner conductor 21 and the outer conductor 22 are made of copper, and a dielectric material separates the inner and outer conductors. The coaxial waveguide 2 of this invention is divided into two parts with different dielectric materials: an upper part using air as the dielectric (air coaxial waveguide) and a lower part using an insulator as the dielectric (dielectric coaxial waveguide). The insulator dielectric 23 is tubularly fixed between the inner conductor 21 and the outer conductor 22. The insulator dielectric 23 is preferably ceramic. In traditional methods, coaxial waveguides using air as the dielectric have low heat exchange efficiency. Using an insulator as the dielectric can improve the heat exchange efficiency between the inner and outer spaces, but the insulator will result in a certain degree of low power capacity. In this invention, by introducing an insulator dielectric 23 on the basis of using air as the dielectric, the heat exchange efficiency between the inner and outer spaces is improved, while overcoming the problem of low power capacity when using only an insulator dielectric, thus improving microwave transmission efficiency. A fin structure 24 is provided on the outer surface of the outer conductor 22. The fin structure 24 increases the contact area between the coaxial waveguide 2 and the air, improves the heat exchange efficiency, and thus improves the stable operating time of the overall structure under high-power microwave input. The gaps between the inner conductor 21 and the insulating medium 23, and between the insulating medium 23 and the inner surface of the outer conductor 22, are filled by a metal coating process, which can further improve the heat exchange efficiency.

[0027] The metal fixing base 4 is arranged between the coaxial waveguide 2 and the antenna body 1, a center hole 41 is arranged on the metal fixing base 4, the inner conductor 21 can pass through the center hole 41 and be connected with the antenna body 1 below the metal fixing base 4, and the outer conductor 22 is fixed on the metal fixing base 4. In the embodiment, the metal fixing base 4 is in the shape of a circular plate, a plurality of screw holes for fixing the metal fixing base 4 on the resonant cavity are arranged at positions close to the edge of the metal fixing base 4, and the antenna is mounted on the cavity by screws. The diameter of the center hole 41 is smaller than the outer diameter of the insulator medium 23, so that the metal fixing base 4 can limit the insulator medium 23 and prevent the insulator medium 23 from falling off the outer conductor 22, and the assembly in production is facilitated.

[0028] The antenna body 1 is fixed below the metal fixing base 4, and the antenna body 1 is composed of antenna arms with different functions, and the materials of the antenna arms are all copper materials. In the embodiment, the antenna body includes an antenna radiation arm 11, an antenna balance arm 12 and an antenna extension arm 13. The antenna radiation arm 11 is in the shape of a strip and parallel to the metal fixing base 4. One end of the antenna radiation arm 11 is an open radiation end, and the size of the antenna radiation arm can be adjusted by bending the end to change the power transmission state. The other end of the antenna radiation arm 11 is connected with the antenna balance arm 12 in the shape of a long strip in the vertical direction. The upper end of the antenna balance arm 12 is connected with the metal fixing base 4 for fixing the antenna body 1. The antenna extension arm 13 is arranged vertically, one end of the antenna extension arm 13 is connected with the inner conductor 21, and the other end of the antenna extension arm 13 is connected with the antenna radiation arm 11. The antenna extension arm 13 is connected with the antenna radiation arm 11 by screws. Further, the antenna extension arm 13 and the inner conductor 21 are in an integrated structure, which is more convenient in the process of processing and assembly. Of course, the antenna extension arm 13 can be processed separately from the inner conductor 21 and then connected by welding or other ways. The antenna radiation arm 11 and the antenna balance arm 12 are in an integrated structure, and the antenna radiation arm 11 and the antenna balance arm 13 are both in the shape of a long strip. The antenna balance arm 11 is connected with the metal fixing base 4 by screws.

[0029] In the embodiment, the air coaxial waveguide, the dielectric coaxial waveguide and the metal fixing base 4 arranged in sequence from top to bottom form a stepped impedance transformation structure, which can reduce the antenna reflection, improve the antenna operating bandwidth and improve the power capacity.

[0030] When the embodiment is used, taking a rectangular resonant cavity as an example, a through hole for inserting the antenna is formed on the metal cavity wall, the antenna is passed out of the cavity in the direction from the cavity to the outside, the metal fixing base 4 is placed inside the metal cavity wall of the rectangular resonant cavity, and the coupling antenna body 1 composed of the antenna radiation arm 11, the antenna balance arm 12 and the antenna extension arm 13 is also located inside the metal cavity wall, the metal fixing base 4 is fixedly connected with the metal cavity wall of the rectangular resonant cavity by using screws, the air radio frequency connector 3 is connected with the microwave source, and the installation of the antenna is completed. The microwave passes through the air radio frequency connector 3, the air coaxial waveguide, the dielectric coaxial waveguide, and is then fed into the rectangular resonant cavity through the coupling antenna, is reflected between the metal cavity walls of the rectangular resonant cavity, and excites the required resonant frequency and mode in the rectangular metal cavity. In the implementation process, Fig. 3 The standing wave diagram of the antenna in the cavity can be seen from the figure, the best reflection point is at 915 MHz, the return loss is about 33 dB, the power transmission efficiency is close to 99% at this time, and the microwave utilization rate is high.

Claims

1. A resonant cavity coupling antenna for microwave heating, characterized by: The application relates to an antenna body, a coaxial waveguide and an air radio frequency connector, wherein the upper end of the antenna body is fixedly connected with the coaxial waveguide, and the upper end of the coaxial waveguide is fixedly connected with the air radio frequency connector; the coaxial waveguide comprises an inner conductor and a tubular outer conductor concentric with the inner conductor, and a medium is arranged between the inner conductor and the outer conductor; the coaxial waveguide comprises an air coaxial waveguide with air as the medium in the upper half and a dielectric coaxial waveguide with an insulator as the medium in the lower half; the insulator medium of the dielectric coaxial waveguide is tubular and fixedly arranged between the inner conductor and the outer conductor; and the lower end of the inner conductor is fixedly connected with the antenna body.

2. The resonant cavity coupling antenna for microwave heating according to claim 1, characterized in that: A metal fixing base for fixing the antenna is fixedly arranged between the antenna body and the coaxial waveguide; a central hole is formed in the metal fixing base; the inner conductor is connected with the antenna body below the metal fixing base through the central hole; and the outer conductor is fixedly arranged on the metal fixing base.

3. The resonant cavity coupling antenna for microwave heating according to claim 2, characterized in that: The antenna body comprises an antenna radiation arm, an antenna balance arm and an antenna extension arm; the antenna radiation arm is parallel to the metal fixing base; the antenna radiation arm is open at one end and connected with the antenna balance arm in the vertical direction at the other end; the upper end of the antenna balance arm is connected with the metal fixing base; and the antenna extension arm is arranged vertically and connected with the inner conductor at one end and the antenna radiation arm at the other end.

4. The resonant cavity coupling antenna for microwave heating according to claim 3, characterized in that: The diameter of the central hole is smaller than the outer diameter of the insulator medium; and a plurality of screw holes for fixing the metal fixing base in a cavity are formed in the metal fixing base.

5. The resonant cavity coupling antenna for microwave heating according to claim 4, characterized in that: The inner conductor and the antenna extension arm are an integral structure; the antenna radiation arm and the antenna balance arm are an integral structure; the antenna radiation arm and the antenna balance arm are long strip-shaped; the antenna balance arm and the metal fixing base are screw-connected; and the antenna extension arm and the antenna radiation arm are screw-connected.

6. The resonant cavity coupling antenna for microwave heating according to any one of claims 1 to 5, characterized in that: The outer surface of the outer conductor is provided with fin structures.

7. The resonant cavity coupling antenna for microwave heating according to claim 6, characterized in that: Metal plating films are fixedly arranged between the inner conductor and the insulator medium and between the insulator medium and the inner surface of the outer conductor.

8. The resonant cavity coupling antenna for microwave heating according to any one of claims 1 to 5, 7, characterized in that: The inner conductor, the outer conductor and the antenna body are made of copper.

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