Asymmetrical Double-Reflector Antenna for Narrow Azimuth Beam
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Solution Overview
Problem
Existing double-reflector antennas face challenges in achieving both compactness and efficient scanning properties, particularly when targeting closely located satellites, as they often require large dimensions and suffer from reduced aperture efficiency due to symmetry constraints and radiation blockage issues.
Innovation Solution
A double-reflector antenna design featuring nonaxisymmetric curvilinear surfaces with two symmetry planes, where the sub-reflector is defined by a polynomial in spherical coordinates and the main reflector has a convex shape, allowing for a compact longitudinal size and efficient beam formation with a narrower beam width in the azimuth plane, thereby optimizing antenna gain and aperture efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If axial symmetrical surfaces are used in double-reflector systems, then the antenna achieves compactness in the longitudinal direction, but the beam width in the azimuth plane becomes too wide to target closely located satellites
Solution Approach 1:
The patent applies asymmetry by using non-axisymmetric surfaces for both the main reflector and sub-reflector. The main reflector has an elliptical cross-section with different semi-axes a and b, while the sub-reflector has an asymmetric conical surface defined by different angles α and β. This asymmetric configuration enables the formation of narrow beams in the azimuth plane while maintaining compact longitudinal dimensions, resolving the contradiction between compactness and beam width control.
2Object-generated harmful factors
If the main reflector dimensions in the azimuth plane are increased to achieve narrow beam width, then the antenna can target closely located satellites, but the longitudinal size and overall complexity increase
Solution Approach 1:
The asymmetric conical sub-reflector with different half-angles α and β in orthogonal planes, combined with the elliptical main reflector, creates a system that achieves narrow azimuth beam width without increasing longitudinal size. The asymmetric geometry transforms the radiation pattern to produce the desired narrow beam characteristics while maintaining a compact low-profile structure.
3Device complexity
If symmetric reflector surfaces are used, then the antenna structure is simpler, but the aperture efficiency decreases when forming elliptic cross-section beams
Solution Approach 1:
The patent employs asymmetric surfaces where the main reflector has an elliptical cross-section and the sub-reflector has a conical surface with different inclination angles. This asymmetric configuration is specifically designed to match the required elliptic beam cross-section, thereby maximizing aperture efficiency for forming narrow beams in the azimuth plane while maintaining structural feasibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances antenna compactness and gain, enabling precise targeting of multiple satellites with reduced unwanted signal reception, improving overall efficiency and scanning capabilities while maintaining a low profile.
Implementation Method 1
a feed (3) arranged between the main reflector (1) and the sub-reflector (2) with the capacity of illuminating, first, the sub-reflector (2) and then, through it, the main reflector (1), in order to allow for a plane wave-front
Data Source
AI summary
The antenna comprises main and sub reflectors, each of which being made with nonaxisymmetric curvilinear surfaces and having two planes of symmetry at the intersection. A feed is arranged between the main and sub reflectors and capable of illuminating, first, the sub-reflector and, through it, the main reflector to form plane wave front. The common focuses of the nonaxisymmetric curvilinear surfaces of the reflectors in all sections passing through the longitudinal axis Z of the antenna, is located at the portion Z0 of Z, wherein the length of said portion being restricted by limits Fmin≦Z0≦Fmax, where Fmin, Fmax are the minimum and maximum distances from the ends of the portion Z0 to the main reflector along Z. The length of Z0 satisfies the following relation; Fmin/Dmax≦Zo/Dmax≦Fmax/Dmax and 0.21≦Zo/Dmax≦0.47, 1>Dmin/Dmax>0.5, where Dmax and Dmin are the maximum and minimum transverse sizes of the main reflector aperture.