Reflector Array Antenna Cross-Polarization Compensation
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Solution Overview
Problem
Reflective array antennas face challenges in minimizing cross-polarization, especially when mounted on satellites pointing towards Earth, due to geometric curvature and primary source performance, leading to increased mass, volume, and cost with dual reflector configurations, and cross-polarization issues in planar reflectarray antennas.
Innovation Solution
A reflective array antenna with cross-polarization compensation is achieved by using a reflective network of elementary radiating elements with asymmetrical etched patterns, specifically angular inclinations of metal patches and slots, to control depolarization and reflection coefficients, ensuring zero cross-polarization components in the desired radiation diagram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a double reflector Gregorian configuration is used to reduce cross-polarization, then the level of cross-polarization is reduced, but the mass, volume and cost of the antenna increase
Solution Approach 1:
The patent applies asymmetry by introducing a compensating phase shift that is not uniform across all radiating elements. Specifically, elements in the first quadrant receive a phase shift of +α, elements in the second quadrant receive -α, elements in the third quadrant receive +α, and elements in the fourth quadrant receive -α. This asymmetric phase distribution compensates for the cross-polarization induced by the offset configuration while maintaining a single planar reflector, thus reducing mass compared to dual reflector systems.
2Object-affected harmful factors
If a double reflector Gregorian configuration is used to reduce cross-polarization, then the level of cross-polarization is reduced, but the volume and cost of the antenna increase
Solution Approach 1:
The asymmetric phase compensation method allows the use of a single planar reflector array instead of a voluminous dual reflector Gregorian configuration. By applying different phase shifts to radiating elements based on their angular position quadrants, the system achieves cross-polarization cancellation in a compact planar structure, significantly reducing the antenna volume while maintaining performance.
3Manufacturing precision
If radiating elements with geometric differences are used to control phase shift, then the phase control precision is improved, but cross-polarization is induced due to geometric curvature effects
Solution Approach 1:
The patent applies local quality by assigning different phase shift characteristics to radiating elements based on their specific angular position. Elements are grouped into four quadrants, and each quadrant receives a specific phase shift value (+α or -α) determined by its angular position. This localized phase compensation approach maintains precise phase control while actively canceling cross-polarization effects that would otherwise be induced by the offset configuration.
Solution Approach 2:
The asymmetric phase distribution across different quadrants compensates for the symmetric cross-polarization induction caused by the offset feed configuration. By applying +α phase shifts to elements in quadrants 1 and 3, and -α phase shifts to elements in quadrants 2 and 4, the system creates an asymmetric compensation pattern that cancels the symmetric cross-polarization interference, thereby reducing harmful effects while maintaining phase precision.
4Volume of stationary object
If a planar reflector array is used instead of a formed surface reflector, then the volume is reduced, but cross-polarization is still induced due to offset illumination
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetric phase compensation to the planar reflector array. Although the physical structure remains planar and compact, the electrical phase distribution is made asymmetric through quadrant-based phase shifting. This asymmetric phase manipulation compensates for the cross-polarization induced by offset illumination, allowing the system to maintain both the volume advantages of a planar array and the cross-polarization performance of formed surface reflectors.
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
The solution effectively cancels cross-polarization generated by the primary source, maintaining high directivity and gain while reducing mass, volume, and cost by optimizing the geometric shape and arrangement of radiating elements, ensuring efficient phase shift control and low depolarization.
Implementation Method 1
a reflective array antenna with cross-polarization compensation comprising a reflective array made up of a plurality of elementary radiating elements regularly distributed and forming a reflecting surface
Implementation Method 2
each radiating element being produced in planar technology and comprising an etched pattern consisting of at least one metallic patch comprising, in a symmetrical configuration having a square geometric shape
Data Source
Figure 1~3
Figure 4a~4b
Figure 5a~5b
AI summary
The invention relates to a reflector array antenna with crossed polarization compensation comprising at least one radiating member (20) having an engraved pattern that is dissymmetrical relative to at least one direction X and/or Y of the plane XY of the radiating member, the dissymmetry of the pattern of the radiating member being calculated individually from a radiating member having the same symmetrical pattern in the two directions X and Y so as to generate a reflected wave having a controlled depolarization opposite to a depolarization generated in a plane normal to a propagation direction by the reflector array (11) illuminated by a primary source (13).