A wideband hat-type feed antenna

Abstract

The application discloses a wide-band hat-type feed antenna and belongs to the technical field of satellite communication antennas. The method adopts a light-wall shaped horn loaded with an outer corrugated slot and a choke slot, improves horn and space matching, realizes expansion of a frequency band from 1.6:1 to 2.8:1, loads a slot at the horn mouth and the edge of the choke slot, realizes equalization characteristics of a feed radiation pattern, adopts a small-size sub-reflector to reduce shielding of the reflector, loads double choke slots in the reflector, reduces diffraction of the sub-reflector, and improves antenna radiation efficiency, and uses spline parameterization of the sub-reflector and the main reflector to realize integrated optimization design, so that the frequency bandwidth of the traditional hat-type feed is expanded, and good side lobe and efficiency performance are realized.

Description

Technical Field

[0001] This invention discloses a novel wideband cap-shaped feed antenna, belonging to the field of satellite communication antenna technology, which can be applied to high-gain, multi-band, wideband and low-sidelobe antenna systems in radar, communication, telemetry and control and other fields. Background Technology

[0002] Typically, the diameter of the subreflector should be greater than five wavelengths of the lowest operating frequency. For small-aperture (D / λ < 20) reflector antennas, the subreflector obstructs the reflected waves from the main reflector too much, resulting in a high first sidelobe and reduced aperture efficiency. In this case, the first sidelobe is difficult to reduce below -14 dB. To further reduce the first sidelobe, the diameter of the subreflector needs to be reduced. However, the interception efficiency is greatly reduced for subreflectors smaller than five wavelengths, and the obstruction caused by a large feed also worsens the sidelobe characteristics and antenna efficiency.

[0003] Traditional cap-shaped feeds can achieve smaller subreflector dimensions (more precisely, the size of the cap), with a diameter that can be designed to be 2-3 wavelengths, achieving a first sidelobe of less than -15dB. However, they can only operate in the Ku or Ka band, with a maximum bandwidth of 1.5 harmonics. Existing technologies struggle to achieve cap-shaped feed antennas with frequencies close to 3 harmonics, especially for small-aperture (D / λ < 20) reflector antennas, which is extremely difficult. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a novel wideband cap-type feed antenna with a bandwidth of 2.8:1, a standing wave ratio (SWR) of less than 1.45, a sidelobe of less than -14 dB, and an efficiency of over 45%. This invention mainly consists of a shaped horn with an external corrugated slot and a choke slot, a subreflector with a choke slot, a dielectric ring supporting the reflector, and a main reflector. The invention also features a compact structure, low SWR, low sidelobe, and high efficiency. Furthermore, this invention does not contain an adjustment structure for the subreflector, eliminating the need for adjustment, and the ring-shaped reflector support structure can withstand high power capacity, meeting the application requirements of next-generation wideband applications such as satellite communication and remote sensing antennas.

[0005] The objective of this invention is achieved as follows:

[0006] A broadband cap-type feed antenna includes, from top to bottom, a sub-reflector, a hollow dielectric ring, an optical wall radiating section, and a main reflector, arranged sequentially and coinciding with the central axis. The optical wall radiating section has a sleeve-type structure, and its outer wall is provided with an integrated helical structure and at least one annular structure, wherein the annular structure is located in the upper half of the optical wall radiating section, and the helical structure is located in the lower half. There is a gap between the annular structure and the optical wall radiating section, forming a choke groove. The helical structure surrounding the outer wall of the optical wall radiating section forms a corrugated groove.

[0007] The annular structure at the top has a slot loaded on its ring wall, and the extension of the hollow medium ring is located in the choke groove with the slot loaded.

[0008] The bottom outer edge of the sub-reflector is loaded with a double choke groove, the opening of the double choke groove is facing downward, and the top of the hollow dielectric ring is located in the outer groove of the double choke groove.

[0009] Furthermore, the top of the inner wall of the light wall radiation section smoothly transitions to the inner wall of the hollow dielectric ring.

[0010] Furthermore, the central axes of both the ring structure and the spiral structure coincide with the central axis.

[0011] Furthermore, the opening of the choke groove faces upwards.

[0012] Furthermore, the center of the sub-reflector is concave.

[0013] The present invention has the following advantages over the prior art:

[0014] 1. This invention significantly expands the frequency bandwidth of the cap-shaped feed to 2.8:1. The broadband of this invention is mainly achieved by using a shaped-curve horn with a light wall and introducing a choke slot to improve the matching between the radiation port and free space, and to enhance the equalization of the horn's radiation pattern.

[0015] 2. The subreflector in this invention employs spline curves to extend the frequency bandwidth. A choke groove is loaded on the outer edge of the subreflector to improve interception efficiency.

[0016] 3. The diameter of the antenna sub-reflector of this invention is selected to be less than 3 wavelengths in order to reduce the obstruction of the sub-reflector. This design concept breaks through the traditional design concept that the diameter of the sub-face needs to be greater than 5 wavelengths in the design of ring focal antennas.

[0017] 4. The novel integrated design of the cap-shaped feed and the main reflector in this invention can infinitely approximate the comprehensive optimal solution of the standing wave ratio, gain and sidelobe performance of a small-aperture antenna.

[0018] In summary, the present invention has a novel concept and high efficiency, and can significantly extend the working bandwidth of the cap-shaped feed antenna, which is a major breakthrough of the prior art. Attached Figure Description

[0019] Figure 1 is a schematic cross-sectional view of the present invention.

[0020] Figure 2 is a physical model of the feed source of the present invention.

[0021] Figure 3 is a physical model of the antenna of the present invention.

[0022] Figure 4 shows the simulated and measured standing wave diagrams of the antenna of this invention.

[0023] Figure 5 shows the simulation and measured radiation patterns of the antenna at the low frequency point of this invention.

[0024] Figure 6 shows the high-frequency simulation and measured radiation patterns of the antenna of the present invention. Detailed Implementation

[0025] See Figure 1 A broadband cap-type feed antenna is provided, including a light wall radiating section 1, a loaded choke slot 2, a spline parameter sub-reflector 3, a sub-reflector loaded with double choke slots 4, a horn radiating port and a choke slot loaded with slots 5, a horn outer wall loaded with an outer corrugated groove 6, a supporting hollow dielectric ring 7, and a spline curve parameter main reflector 8.

[0026] The optical wall horn with loading choke slot is connected to the sub-reflector of loading choke slot through a supporting dielectric ring to form a broadband novel cap-shaped feed. The cap-shaped feed is installed at the center of the main reflector with spline parameters to form a broadband novel cap-shaped feed antenna.

[0027] The feed uses a shaped horn with a light wall and a choke slot to improve the matching between the radiation port and free space, thereby enhancing the equalization of the horn's radiation pattern and the performance of its wide-angle sidelobes.

[0028] The subreflector employs a spline curve to extend the frequency bandwidth. Dual choke slots are loaded on the outer edge of the subreflector to improve interception efficiency. The diameter of the subreflector is chosen to be less than three wavelengths to reduce obstruction. This design concept represents a breakthrough from traditional ring-focus antenna design.

[0029] The use of a ring-shaped dielectric support between the shaped horn with external corrugated slots and choke slots and the subreflector can meet the requirements of high power capacity. This novel integrated and optimized design of the cap-shaped feed and main reflector can further improve the antenna's standing wave ratio, gain, and sidelobe performance.

[0030] Figure 2 and Figure 3 The feed source and antenna product diagrams of embodiments of the present invention are given, and their operating frequency bands cover the Ka / Ku bands.

[0031] Figure 4Simulated and measured standing wave ratios within the operating frequency band are presented. It can be seen that the voltage standing wave ratio is less than 1.45 within the designed bandwidth, and the operating bandwidth can reach 2.8:1.

[0032] Figure 5 and Figure 6 The radiation patterns of the azimuth and elevation planes at the corresponding high and low frequencies within a certain operating frequency band are given. It can be seen that within the designed bandwidth, the measured and simulated antenna patterns match well, and the sidelobes of both the azimuth and elevation planes are below -14dB.

[0033] The results show that, compared with the prior art, the present invention has a significantly increased operating bandwidth of up to 2.8:1, good sidelobe performance and electrical performance such as standing wave ratio, and a compact structure.

[0034] Brief working principle of the invention:

[0035] The novel wideband cap-type feed antenna mainly employs a shaped horn with an external corrugated slot and a choke slot to improve the horn's spatial matching and achieve bandwidth expansion. Gaps are added at the horn opening and the edge of the choke slot to achieve equalization of the feed radiation pattern. Small-sized subreflectors are used to reduce reflector obstruction, and the choke slot-loaded reflector reduces diffraction by the subreflector, improving antenna radiation efficiency. Spline-parameterized subreflectors and main reflectors extend the frequency bandwidth of traditional cap-type feeds and achieve good sidelobes and efficiency performance.

Claims

1. A wide-band hat-feed antenna, characterized by The parabolic reflector comprises, from top to bottom, a secondary reflector, a hollow dielectric ring, a light-wall radiation section and a primary reflector, which are arranged in sequence and coincide with the central axis; the light-wall radiation section is of sleeve type structure, and the outer wall of the light-wall radiation section is provided with an integral spiral structure and at least one annular structure, wherein the annular structure is located in the upper half of the light-wall radiation section, and the spiral structure is located in the lower half; the annular structure and the light-wall radiation section have a gap therebetween, forming a choke groove; The spiral structure around the outer wall of the light-wall radiation section forms a corrugated groove; The annular wall of the annular structure at the top is loaded with a slit, and the extended section of the hollow dielectric ring is located in the choke groove loaded with the slit; The bottom outer edge of the secondary reflector is loaded with a double choke groove, and the openings of the double choke groove face downward, and the top end of the hollow dielectric ring is located in the outer groove of the double choke groove.

2. A wide-band hat-feed antenna according to claim 1, characterized in that The inner wall top end of the light-wall radiation section and the inner wall of the hollow dielectric ring are smoothly connected.

3. A wide-band hat-feed antenna according to claim 1, characterized in that The central axes of the annular structure and the spiral structure coincide with the central axis.

4. A wide-band hat-feed antenna according to claim 1, characterized in that The openings of the choke groove face upward.

5. A wide-band hat-feed antenna according to claim 1, characterized in that The secondary reflector is centrally concave.

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