Active Antenna Array Sidelobe Control via Aperture Reshaping
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Solution Overview
Problem
Existing active electronically steered array (AESA) technologies face challenges in reducing sidelobe levels while maintaining illumination efficiency, as methods like non-uniform amplitude illumination and phase tapering result in reduced radiated signal power and are difficult to implement effectively.
Innovation Solution
The method involves electronically reshaping the antenna aperture by varying the angle of edge discontinuities or deactivating radiators to form a parallelogram-shaped aperture, which moves sidelobes off the principal plane, thereby reducing sidelobe levels without compromising effective isotropic radiated power (EIRP) or gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If non-uniform amplitude illumination distributions are used to reduce sidelobe levels, then sidelobe levels are reduced, but radiated signal power levels decrease due to inherent inefficiency
Solution Approach 1:
The patent applies asymmetry by transitioning from a symmetric rectangular aperture to an asymmetric tapered aperture configuration. The aperture illumination is shaped with different amplitude distributions across its extent, creating an asymmetric field pattern that directs sidelobes away from the principal plane while maintaining overall radiation efficiency. This asymmetric shaping reduces sidelobe levels in critical regions without the significant power loss associated with uniform tapering approaches.
Solution Approach 2:
The patent implements local quality by applying non-uniform amplitude illumination specifically at the edges and corners of the aperture rather than uniformly across the entire aperture. The illumination distribution is tailored locally at discontinuity regions to control sidelobe generation, while the central region maintains higher illumination for efficient main beam radiation. This localized approach reduces sidelobes without compromising overall radiated signal power.
2Object-generated harmful factors
If phase tapering techniques are used to reduce sidelobe levels, then sidelobe levels are reduced, but implementation complexity increases and radiated signal power levels decrease
Solution Approach 1:
The patent replaces complex phase tapering mechanisms with a simpler geometric aperture shaping approach. Instead of using complex phase shifters and control systems to achieve sidelobe reduction, the invention uses a physically tapered aperture configuration that naturally produces the desired sidelobe pattern through its geometry. This substitution of mechanical/phase-control complexity with geometric simplicity reduces implementation complexity while maintaining effectiveness.
3Object-generated harmful factors
If aperture reshaping is used to reduce sidelobe levels, then sidelobe levels are reduced over selected regions, but maintaining maximum EIRP and gain becomes challenging
Solution Approach 1:
The patent applies partial action by implementing aperture tapering that is sufficient to reduce sidelobes in critical regions but not so extreme as to significantly compromise main beam performance. The illumination distribution is shaped to achieve the minimum necessary tapering to move sidelobes away from the principal plane, thereby maintaining maximum EIRP and gain while still achieving the desired sidelobe reduction effect in the most problematic angular regions.
Data Source
AI summary
A method of controlling sidelobe distribution in an active electronically steered array, including electronically reshaping the array aperture so as to reduce sidelobes over a selected region of a coverage volume of the array. In one example, reshaping of the aperture is achieved by electronically turning on and/or off selected radiators in the array to vary the angle of edge discontinuities of the aperture, and thereby move the main sidelobes off the principal plane(s) of operation of the array.