CN102904064A - an antenna - Google Patents

Abstract

The invention relates to an antenna, comprising a microstrip exciter (1) and a cavity (2); the top diameter of the cavity (2) is larger than the bottom diameter; the cavity (2) includes sequentially distributed from bottom to top A plurality of conical cavities, the slope of the plurality of conical cavities distributed from bottom to top gradually increases; the microstrip actuator is located in the cavities (2). The antenna of the invention has the characteristics of high gain, miniaturization, simple structure and easy processing.

Description

an antenna

technical field

The invention relates to an antenna.

Background technique

In the field of microwave communication, a satellite S-band phased array antenna (receiving antenna working in the S-band) is a phased array antenna with high gain and large-scale scanning, and the working mode is dual circular polarization. , and reduce the number of antenna elements and channels, and put forward the requirements of high gain and miniaturization for the antenna elements. A common method to increase the gain of the antenna unit is an antenna with a radiating cavity, such as adding a horn structure in the radiation direction of the microstrip patch to increase the gain, but the efficiency of this type of structural antenna is relatively low, and the main lobe of the antenna pattern is symmetric and The roll-off is poor, and the antenna size and quality are relatively large. At present, most of the existing high-gain enhanced antennas at home and abroad have the following disadvantages: a. large size, large volume, and low aperture efficiency; b. complex structure and difficult to process.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an antenna with high gain, miniaturization, simple structure and easy processing.

Above-mentioned purpose of the present invention is achieved by following technical scheme:

An antenna, including a microstrip exciter and a cavity; the top diameter of the cavity is larger than the bottom diameter; the cavity includes a plurality of tapered cavities distributed sequentially from bottom to top, and a plurality of tapered cavities distributed from bottom to top The slope of the tapered cavity gradually becomes larger; the microstrip actuator is located in the cavity.

There are three tapered cavities.

The height of each tapered cavity is equal to 1/4 of the working wavelength.

The microstrip exciter includes an upper parasitic patch, a lower radiation patch and a dielectric support rod; the dielectric support rod suspends the upper parasitic patch and the lower radiation patch in the air.

Both the upper parasitic patch and the lower radiation patch are circular.

The medium support rods are four polyimide medium rods.

The bottom of the cavity serves as a ground plate for the microstrip driver.

The antenna also includes a feeding part, the feeding part includes a plurality of coaxial feeding probes, and a plurality of through holes for accommodating the feeding probes are formed at the bottom of the cavity, and the plurality of coaxial feeding probes are formed at the bottom of the cavity. The shaft-fed probe is in contact with the underlying radiating patch.

The plurality of coaxial feeding probes are four square coaxial feeding probes.

Compared with the prior art, the present invention has the following advantages:

1. By adopting a multi-stage tapered cavity structure, the section of the cavity can be effectively reduced, so that it has a compact structure; the adoption of this abruptly discontinuous structure strengthens the significant concentration of the local field strength in the cavity, and makes the electromagnetic wave radiate backward Reflection occurs and is superimposed in phase with the forward radiation wave, and finally the forward radiation of the antenna is enhanced to the maximum, so that the antenna obtains high gain and good main lobe characteristics, and the antenna aperture efficiency reaches 94.8%; the antenna structure is compact and easy to form an array, and can Realize the miniaturization and light weight of the array;

2. The antenna structure of the present invention overcomes many shortcomings of traditional corrugated horns and helical antennas, and has the advantages of high strength, low profile, simple structure, easy processing and easy installation, excellent electrical performance, and high gain and high efficiency.

3. Using the antenna as an array element facilitates miniaturization and light weight of the antenna array, so it has broad application prospects in phased array antenna systems, especially in high-orbit electronic reconnaissance satellite receiving antenna systems.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the high-gain multi-stage tapered cavity antenna of the present invention;

2 is a cross-sectional view of the structure of the high-gain multi-stage tapered cavity antenna of the present invention;

Fig. 3 is the structure schematic diagram of microstrip exciter of the present invention;

Fig. 4 is a schematic diagram of the structure of the multi-stage conical radiation cavity of the present invention;

Fig. 5 is a schematic diagram of the structure of the square coaxial feeding part of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment content of the present invention is described in further detail:

As shown in Figure 1, it is a schematic diagram of the antenna structure of the present invention, and as shown in Figure 2, it is a sectional view of the antenna structure of the present invention, as can be seen from the figure that the antenna of the present invention includes a microstrip exciter 1, a multi-stage tapered radiation cavity Body 2, and feeder part 3. The top of the multi-stage tapered radiation cavity 2 is open and the bottom is closed. The diameter of the top is larger than the diameter of the bottom. The slope of the multi-stage tapered radiation cavity 2 becomes larger successively. The microstrip exciter 1 is located in the cavity 2 and installed at the center of the bottom of the cavity 2 ; the microstrip exciter 1 is fed through the feeding part 3 . The use of a multi-stage tapered cavity can improve antenna efficiency and gain while reducing the height of the antenna profile. The maximum diameter of the antenna in this embodiment is in the range of 250 mm to 265 mm, and the maximum cross-sectional height of the antenna is in the range of 95 mm to 105 mm. Determine the series of tapered cavity according to the antenna gain requirements, antenna aperture and section height requirements; the fewer the series, the lower the antenna section height, but to achieve 15dBi gain, it will make the main lobe symmetry and roll of the antenna pattern At the same time, the antenna aperture efficiency becomes lower; the higher the number of series, the better the symmetry and roll-off of the main lobe of the antenna square diagram, but the higher the height of the antenna profile, it is not conducive to the miniaturization and light weight of the antenna. Too many will also lead to a decrease in the utilization efficiency of the antenna aperture, and at the same time, the increase in mutual coupling will not be conducive to the antenna array. The slope of the cone is determined by the height of each conical cavity and the diameter of the bottom and top surfaces of the conical cavity. The height of each conical cavity is equal to 1/4 of the working wavelength. According to the antenna gain requirements and the goal of maximizing the antenna aperture efficiency , strengthen the concentration of the local field strength in the cavity, and optimize the design of the bottom and top diameters of each conical cavity.

As shown in FIG. 3 , the microstrip driver 1 is composed of an upper parasitic patch 4 , a lower radiation patch 5 and four polyimide dielectric support rods 6 for support. Four dielectric support rods 6 made of polyimide material are evenly distributed on the same circumference, and are used to suspend the upper layer parasitic patch 4 and the lower layer radiation patch 5 in the air. One end of the dielectric support rod 6 is fixed to the upper parasitic patch 4 , and the other end passes through the lower radiation patch 5 and contacts the bottom of the cavity 2 (as shown in FIG. 2 ). Both the parasitic patch 4 and the radiation patch 5 adopt a circular structure. The radius of the upper parasitic patch 4 is smaller than that of the lower radiation patch 5 , the upper parasitic patch 4 is mainly used to widen the bandwidth, and the lower radiation patch 5 is mainly used to adjust the gain. The diameter d4=52mm of the upper parasitic patch 4, the height h4=17mm relative to the bottom of the multi-stage tapered radiation cavity, the thickness m4=1mm, the diameter d5=75mm of the radiation patch 5, relative to the multi-stage tapered radiation cavity The height of the bottom of the shaped radiation cavity h5=5.8mm, and the thickness m5=1mm. The microstrip exciter adopts a double-layer structure. The parasitic patch and the radiation patch adopt a suspended structure and are supported by four polyimide dielectric rods. The above structure effectively widens the antenna impedance bandwidth and reduces loss.

As shown in Figures 2 and 4; the multi-stage tapered cavity 2 is preferably three-stage, consisting of a first-stage tapered cavity 7, a second-stage tapered cavity 8 and a third-stage tapered cavity 9, The diameter of the top surface of the first-stage conical cavity 7 is equal to the diameter of the bottom surface of the second-stage conical cavity 8 , and the diameter of the top surface of the second-stage conical cavity 8 is equal to the diameter of the bottom surface of the third-stage conical cavity 9 . The slope of the three-stage conical cavity becomes larger in turn. The bottom surface of the multi-stage tapered cavity 2 is used as a grounding plate, and four square holes 10 for accommodating feeding probes are provided. As shown in the sectional view in Figure 2, taking the bottom line of the conical cavity as the reference line, taking the tangent value of the angle between the busbar of each cavity and the reference line is the slope of the cone of each cavity. Wherein the diameter of the bottom surface of the first-stage conical cavity 7 is d7=190mm, and the slope of the cone is k1=1.6; the diameter of the bottom surface of the second-stage conical cavity 8 is d8=233.4mm, and the slope of the cone is k2=3.8; The diameter of the bottom surface of the conical cavity 9 is d9=251.8mm, the slope of the cone is k3=8.5, the diameter of the top surface (the maximum diameter of the mouth surface) is 260mm, and the height of each conical cavity is equal to 1/4 of the working wavelength, multi-level gradient The maximum diameter of the tapered cavity 2 is 1.86 working wavelength. The high-gain multi-level tapered cavity antenna adopts 3 levels of tapered cavity with different slopes, which can significantly concentrate the local field strength in the cavity, and maximize the antenna aperture efficiency and antenna direction while achieving a high gain of 15dB i. The main lobe in the figure is close to linear roll-off, and the overall section height of the antenna is relatively low, which facilitates the miniaturization and weight reduction of the antenna.

As shown in Figure 5, the feeding part 3 includes a plurality of coaxial feeding structures, and the plurality of coaxial feeding structures are preferably 4 square coaxial feeding structures, and the square coaxial feeding structure is formed by a square coaxial feeding structure. The electrical probe 11 is composed of a square coaxial medium 12 and a square coaxial outer conductor 13. Four square coaxial feeding probes 11 pass through the through hole 10 at the bottom of the cavity 2 and then contact the lower radiation patch 5. The four square coaxial feeding probes 11 are centered on the center of the bottom of the cavity 2 and distributed on the same circumference; their amplitudes are the same, and their phases are sequentially different by 90°. The feeding part uses four square coaxial feeding probes 11 with a phase difference of 90° in sequence to feed the lower radiation patch 5 in a balanced manner, which can conveniently obtain dual circular polarization performance and significantly improve the axial ratio bandwidth and circular polarization performance.

The working principle of the antenna of the present invention is as follows:

The antenna consists of a microstrip exciter and a multi-stage tapered cavity. The microstrip exciter adopts a double-layer structure, consisting of two patches with different diameters and heights suspended in the air, which are used to widen the impedance bandwidth and reduce loss. , in which the lower radiation patch is fed by four square coaxial feeding probes with the same amplitude and 90° phase difference in turn; the multi-stage tapered cavity adopts a gradual three-level cavity structure with different slopes. The microstrip exciter only radiates a single TE11 mode electromagnetic wave, which suppresses the generation of high-order modes. At the same time, these abruptly discontinuous structures strengthen the significant concentration of the local field strength in the cavity; by comprehensively optimizing the slope of each cone and cone Height, so that the backward radiation electromagnetic wave is reflected and superimposed in phase with the forward radiation wave until the required high gain is met, while the main lobe of the pattern is close to linear roll-off, and the maximum diameter and section of the radiation cavity are minimized, and finally a design with High gain antenna with good electrical performance.

Through the above design, the electrical performance of the high-gain multi-stage tapered cavity antenna of the present invention can reach:

Polarization mode: left and right circular polarization;

Gain: 15.1dBi; the maximum gain at the center frequency of the antenna is 15.1dBi, which is greater than 15dBi within the relative bandwidth of 7.2%, the symmetry of the main lobe of the pattern is relatively good, the main lobe of the pattern is tapered and rolled off quickly, and the aperture efficiency of the antenna is 94.8%.

Standing wave: <1.4 (within the bandwidth); the antenna can obtain the performance of VSWR<1.4 within 14% of the relative bandwidth.

Axial ratio: <1.2dB (in the bandwidth range); less than 1.2dB in the ±25° beam range, good circular polarization characteristics.

Since the high-gain multistage tapered cavity antenna of the present invention has the advantages of high gain, high efficiency, low profile, antenna pattern main lobe symmetry and good roll-off, the high-gain multistage tapered cavity antenna of the present invention The body antenna can form a 32-element sparse antenna array. When the diameter of the antenna array is less than 2m and the scanning angle is ±13°, the gain is greater than 28.1dBi, and the sidelobe of the array is suppressed to less than -16dB.

The above description is only the best specific implementation mode of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention.

The content that is not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (9)

1. an antenna comprises micro-strip excitation device (1) and cavity (2); Cavity (2) top diameter larger than base diameter; It is characterized in that: described cavity (2) comprises a plurality of cone-shaped cavities that distribute successively from top to bottom, and the slope of a plurality of cone-shaped cavities that distribute from top to bottom becomes large gradually; Described micro-strip excitation device is positioned at cavity (2).

2. multistage gradual change cone-shaped cavity antenna according to claim 1, it is characterized in that: described a plurality of cone-shaped cavities are 3.

3. multistage gradual change cone-shaped cavity antenna according to claim 1 and 2, it is characterized in that: the height of each cone-shaped cavity is equal to 1/4 operation wavelength.

4. antenna according to claim 1 is characterized in that: described micro-strip excitation device (1) comprises upper strata parasitic patch (4), lower floor's radiation patch (5) and dielectric support rod (6); Described dielectric support rod (6) is suspended from upper strata parasitic patch (4) and lower floor's radiation patch (5) in the air.

5. antenna according to claim 4, it is characterized in that: described upper strata parasitic patch (4) and lower floor's radiation patch (5) are circle.

6. it is characterized in that according to claim 4 or 5 described antennas: described dielectric support rod (6) is four polyimides dielectric rods (6).

7. according to claim 1 or 4 described antennas, it is characterized in that: the bottom of described cavity (2) is as the ground plate of micro-strip excitation device (1).

8. multistage gradual change cone-shaped cavity antenna according to claim 7, it is characterized in that: described antenna also comprises feed part (3), described feed part (3) comprises a plurality of coaxial feed probe, form a plurality of through holes be used to holding described feed probes in the bottom of cavity (2), described a plurality of coaxial feed probe contact with lower floor's radiation patch (5).

9. multistage gradual change cone-shaped cavity antenna according to claim 8, it is characterized in that: described a plurality of coaxial feed probe are 4 square coaxial feed probe.

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