A four-ridged horn feed based on a frequency selective surface

Abstract

The application provides a four-ridged horn feed based on a frequency selective surface and belongs to the fields of communication, measurement and control and remote sensing receiving. The four-ridged horn feed comprises a four-ridged horn and a four-ridged horn waveguide. The four-ridged horn waveguide is connected to the input port of the four-ridged horn. The bottom of the ridge inside the four-ridged horn extends into the four-ridged horn waveguide. The four-ridged horn is also provided with a frequency selective surface structure. The frequency selective surface structure corresponds to the ridge one by one. The frequency selective surface structure mainly comprises a dielectric plate and a plurality of selection surface units. The vertical slot for connecting the ridge is arranged at the middle position of the dielectric plate, and the inner side of the ridge is inserted into the vertical slot. The plurality of selection surface units are arranged in the form of a rectangular array on the inner surface of the dielectric plate. The application realizes a small horn radiation aperture, so that the radiation aperture electric size of the horn feed remains basically constant in the whole frequency band, and the radiation pattern beam width is basically constant.

Description

Technical Field

[0001] This invention relates to the fields of communication, measurement and control and remote sensing reception, and in particular to the design of a four-ridged horn feed based on a frequency selective surface. Background Technology

[0002] The feed is a key component of a reflector antenna, and its performance directly affects the overall antenna performance. To detect a wider range of signals with varying strengths and frequencies, the feed antenna, as a core component, needs to have a wide bandwidth. This means the feed needs high illumination efficiency, stable radiation characteristics, a stable phase center, and a low reflection coefficient across a broad frequency band. Extensive research has been conducted by scholars both domestically and internationally to achieve wide-bandwidth feeds. Currently, the main implementations of wide-bandwidth feeds include Eleven Feed, ATA Feed, Sinuous Feed, and horn Feed. While Eleven Feed, ATA Feed, and Sinuous Feed can achieve wide bandwidth and relatively stable radiation characteristics, feeding them is difficult to implement because the feeding of the two arms requires a 180° phase difference. This necessitates additional components for balanced feeding, and maintaining a 180° phase difference across the entire frequency band is challenging. Sinuous Feed can also achieve a wide bandwidth; however, the radiation pattern becomes asymmetrical with frequency variations, exhibiting an elliptical shape. In horn feeds, the corrugated horn is the most classic feed structure, possessing advantages such as rotationally symmetric radiation patterns and constant beamwidth within the frequency band. However, its structural characteristics limit its bandwidth ratio. By adding a gradually tapering ridge structure to a traditional horn, wideband characteristics can be achieved, and ridged horn feeds use coaxial feeding, making the feeding method simple. Therefore, ridged horn feeds are widely used. However, for ridged horn feeds, as the operating frequency increases, the electrical size of the horn aperture gradually increases. Consequently, the beamwidth of its E-plane and H-plane radiation patterns becomes significantly narrower, especially the H-plane radiation pattern beamwidth, and the equalization of the E-plane and H-plane radiation patterns also deteriorates. This limits the realization of wideband in four-ridged horn feeds. Summary of the Invention

[0003] In view of this, the present invention provides a four-ridged horn feed based on a frequency-selective surface. By loading a frequency-selective surface that exhibits reflection characteristics in the high-frequency band into the horn feed, the horn wall of the horn feed is a new horn wall composed of a frequency-selective surface structure in the high-frequency band, thereby achieving a smaller horn radiation aperture. This ensures that the electrical size of the horn feed's radiation aperture remains essentially constant throughout the entire frequency band, achieving a essentially constant radiation pattern beamwidth.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A frequency-selective surface-based four-ridged horn feed includes a four-ridged horn and a four-ridged horn waveguide; the four-ridged horn waveguide is connected to the input port of the four-ridged horn.

[0006] The bottom of the ridges inside the four-ridged horn extends into the waveguide of the four-ridged horn; the four-ridged horn also has a frequency selective surface structure inside; the frequency selective surface structure corresponds one-to-one with the ridges; the frequency selective surface structure is mainly composed of a dielectric substrate and multiple selective surface units; the middle position of the dielectric substrate has a vertical slot for connecting the ridges, and the inner side of the ridges is inserted into the vertical slot; the multiple selective surface units are arranged in a rectangular array on the inner surface of the dielectric substrate;

[0007] The four-ridged horn waveguide has a coaxial feed structure on one of its adjacent waveguide surfaces; the outer conductor of the coaxial feed structure is connected to the waveguide surface on which it is located, and its inner conductor is connected to the ridge on the opposite side.

[0008] Furthermore, the dielectric plate is trapezoidal.

[0009] Furthermore, there are three array groups of selected surface units on the dielectric substrate, wherein the number of selected surface units arranged horizontally in the three array groups from top to bottom decreases sequentially.

[0010] Furthermore, the coaxially fed inner conductor passes through the waveguide surface and ridge on the same side, and is not in contact with either of them.

[0011] Furthermore, the coaxial feed structure is perpendicular to the waveguide surface in which it is located.

[0012] Furthermore, adjacent dielectric substrates are edge-to-edge connected, and the lower edge of the dielectric substrate is connected to the upper edge of the four-ridged horn waveguide.

[0013] Furthermore, the selected surface unit is a circular metal patch with four rectangular cutouts; the rectangular cutouts are evenly distributed on the circular metal patch.

[0014] The beneficial effects of the above-mentioned technical solution adopted by the present invention are as follows:

[0015] 1. Loading a frequency-selective surface structure into a four-ridged horn feed can expand the beamwidth in the high-frequency band, thereby achieving a stable radiation pattern within the frequency band.

[0016] 2. The concentration of electromagnetic waves can be adjusted by changing the angle between the frequency selection surface periodic structure and the horn wall. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0018] Figure 1 This is a schematic diagram of a four-ridged horn feed based on a frequency-selective surface.

[0019] Figure 2 This is a cross-sectional view of a four-ridged horn feed structure based on a frequency-selective surface.

[0020] Figure 3 It is a schematic diagram of a frequency-selective surface periodic structure.

[0021] Figure 4 This is a schematic diagram of a traditional frequency-selective surface unit structure.

[0022] Figure 5 This is a schematic diagram of a miniaturized frequency-selective surface unit structure.

[0023] Figure 6 Simulation results for the transmission coefficients of traditional and miniaturized frequency-selective surface units.

[0024] Figure 7 Simulation results of voltage standing wave ratio.

[0025] Figure 8 Electric field distribution at 7 GHz for unloaded / loaded frequency-selective structure aperture at four-ridged horns.

[0026] Figure 9 Four-ridged horn unloaded / loaded frequency-selective structure E-plane beamwidth.

[0027] Figure 10 Four-ridged horn unloaded / loaded frequency-selective structure H-plane beamwidth. Detailed Implementation

[0028] In the following description, specific details such as particular device structures and techniques are set forth for illustrative purposes and not for limitation, so as to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0029] A frequency-selective surface-based four-ridged horn feed consists of a four-ridged horn, a four-ridged horn waveguide, a first coaxial feed structure, a second feed structure, and a frequency-selective surface structure. The four-ridged horn 1 is connected to the four-ridged waveguide 2. The inner conductors of the first coaxial feed structure 3 and the second feed structure 4 pass through the ridges and are connected to the ridges on their respective sides. The frequency-selective surface structure 5 is composed of four trapezoidal periodic frequency-selective surface structures and is embedded in the four-ridged horn. In the high-frequency band, the horn wall of this horn feed is a new horn wall composed of the frequency-selective surface structure, thus achieving a smaller horn radiation aperture.

[0030] Further frequency selection can be applied to surface unit structures in other shapes.

[0031] The concentration of electromagnetic waves can be further adjusted by changing the angle between the frequency selection surface periodic structure and the horn wall.

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0033] like Figure 1 , Figure 2 As shown, a four-ridged horn feed based on a frequency selective surface (FSE) comprises a four-ridged horn 1, a four-ridged horn waveguide 2, a first coaxial feed structure 3, a second feed structure 4, and a frequency selective surface structure 5. The four-ridged horn 1 and the frequency selective surface structure 2 are placed inside the horn feed. The four-ridged horn 1 is connected to the four-ridged waveguide 2. The conductors inside the first coaxial feed structure 3 and the second feed structure 4 pass through the ridges and connect to their respective opposite ridges. The frequency selective surface structure 5 is composed of four identical trapezoidal periodic frequency selective surface structures and is embedded in the four-ridged horn. To avoid contact, slots are made at the intersections of the frequency selective surface and the ridges.

[0034] like Figure 3 As shown, each frequency-selective surface periodic structure is composed of 96 miniaturized frequency surface units printed on a dielectric substrate. Figure 4 As shown, this invention extends the traditional band-stop characteristic ring structure by bending it towards the center at four positions (up, down, left, and right), thereby miniaturizing the unit structure and ensuring that each frequency-selective surface periodic structure can be composed of a sufficient number of unit structures to exhibit good band-stop characteristics. Figure 5 and Figure 6As shown, compared with traditional circular frequency selective surface elements, the miniaturized frequency selective surface bandstop characteristics can be achieved at low frequencies. Four trapezoidal printed circuit board structures form a closed horn wall structure. When the operating frequency of the horn feed is within the bandstop band of the frequency selective surface, the electromagnetic waves in the horn feed are focused within the closed horn wall structure formed by the frequency selective surface structure. This allows for the control of the horn feed's radiation aperture, solving the problem of beamwidth narrowing with increasing frequency, significantly improving the antenna illumination efficiency of the horn feed, and ultimately achieving broadband performance.

[0035] like Figure 7 As shown, a four-ridged horn feed based on a frequency-selective surface has a voltage standing wave ratio of less than 2 in the 1-9 GHz frequency band and exhibits good matching characteristics.

[0036] like Figure 8 As shown, by selecting the surface structure by loading the frequency, the effective radiation area of ​​the four-ridged horn feed at the 7GHz frequency is significantly reduced, and its radiation beamwidth is increased.

[0037] like Figure 9 and Figure 10 As shown, by loading a frequency-selective structure, the beamwidth of both the E-plane and H-plane of the four-ridged horn in the 6–7.5 GHz frequency band is significantly extended.

[0038] Brief working principle of the invention:

[0039] The working principle of this invention is as follows: A four-ridged horn feed based on a frequency selective surface comprises a four-ridged horn, a four-ridged horn waveguide, a first coaxial feed structure, a second feed structure, and a frequency selective surface structure. The four-ridged horn 1 is connected to the four-ridged waveguide 2. The inner conductors of the first coaxial feed structure 3 and the second feed structure 4 pass through the ridges and are connected to the ridges on their respective sides. The frequency selective surface structure 5 is composed of four trapezoidal periodic frequency selective surface structures and is embedded in the four-ridged horn. In the high-frequency band, the horn wall of this horn feed is a new horn wall composed of the frequency selective surface structure, thus achieving a smaller horn radiation aperture.

Claims

1. A four-ridged horn feed based on a frequency-selective surface, characterized in that, It includes a four-ridged horn and a four-ridged horn waveguide; the four-ridged horn waveguide is connected to the input port of the four-ridged horn; The bottom of the ridges inside the four-ridged horn extends into the waveguide of the four-ridged horn; the four-ridged horn also has a frequency selective surface structure inside; the frequency selective surface structure corresponds one-to-one with the ridges; the frequency selective surface structure is composed of a dielectric substrate and multiple selective surface units; the middle position of the dielectric substrate has a vertical slot for connecting the ridges, and the inner side of the ridges is inserted into the vertical slot; the multiple selective surface units are arranged in a rectangular array on the inner surface of the dielectric substrate; The four-ridged horn waveguide has a coaxial feed structure on one of its adjacent waveguide surfaces; the outer conductor of the coaxial feed structure is connected to the waveguide surface on which it is located, and its inner conductor is connected to the ridge on the opposite side. The dielectric plate is trapezoidal; There are three array groups of selected surface cells on the substrate, and the number of selected surface cells arranged horizontally in the three array groups from top to bottom decreases sequentially. The coaxially fed inner conductor passes through the waveguide surface and ridge on the same side, and is not in contact with either of them; The coaxial feed structure is perpendicular to the waveguide surface it is located on; Adjacent dielectric substrates are edge-to-edge connected, and the lower edge of the dielectric substrate is connected to the upper edge of the four-ridged horn waveguide. The selected surface unit is a circular metal patch with four rectangular cutouts; the rectangular cutouts are evenly distributed on the circular metal patch.

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