Stepped Satellite Reflector for Stable Null Steering
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Solution Overview
Problem
Conventional satellite antenna reflectors are sensitive to random surface errors and feed pattern errors, leading to instability in producing a near-zero field strength region, which is essential for rejecting unwanted signals.
Innovation Solution
A satellite antenna with a reflector having a stepped profile, such as a radial or spiral step, that generates a sharp, deep region of near-zero field strength, which is robust to surface and feed pattern errors, and can be steered to reposition the null as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional smooth reflector profiles are used to produce near-zero field strength regions, then the radiation pattern can be shaped, but the resulting null is sensitive to random surface errors and feed pattern errors
Solution Approach 1:
The reflector surface is segmented into discrete steps rather than being smooth and continuous. This segmentation creates a stepped profile that generates a more stable and robust near-zero field strength region that is less sensitive to manufacturing errors and surface irregularities.
Solution Approach 2:
The reflector surface is designed with different local properties - specifically, a stepped profile in the region where near-zero field strength is required. This local modification of the surface geometry creates a more stable null pattern that is resistant to errors while maintaining the overall contoured beam shape.
2Reliability
If smooth reflector surfaces are used, then manufacturing is easier, but the near-zero field strength region is unstable and sensitive to errors
Solution Approach 1:
The continuous smooth surface is divided into discrete stepped segments. While this increases manufacturing complexity compared to a smooth surface, it provides significantly improved robustness and stability of the near-zero field strength region, making the antenna more reliable in practical applications.
3Manufacturing precision
If conventional synthesis software is used to generate reflector profiles, then the desired beam pattern can be produced, but quadratic cancellation patterns are sensitive to random surface errors
Solution Approach 1:
Instead of using conventional smooth reflector profiles generated by synthesis software, the invention employs a stepped profile that segments the continuous surface. This segmentation creates a radiation pattern with a more stable null that is less sensitive to random surface errors, while still achieving the desired beam pattern accuracy.
Solution Approach 2:
Rather than trying to achieve null cancellation through smooth continuous variations in the reflector profile, the invention inverts the approach by using discrete stepped variations. This inverse approach to profile design produces a more robust cancellation pattern that is less sensitive to errors.
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 stepped profile design provides a robust and adjustable near-zero field strength region, minimizing signal power to unwanted receivers and resisting errors, ensuring effective interference rejection and jamming prevention.
Implementation Method 1
the surface of the reflector in the reflector antenna can be modified during the design process using reflector profile synthesis software to produce the required beam pattern... to generate a far field pattern with near-zero field strength at a predetermined location
Data Source
AI summary
A satellite antenna arrangement for a satellite communication system comprising: a reflector for producing a far field pattern with near-zero field strength at a predetermined location to reject unwanted signals from said predetermined location or minimise signal power transmitted to said predetermined location, the reflector having a surface comprising a stepped profile arranged to generate the near-zero field strength in the predetermined location. The stepped profile may comprise a radial step. The location of the near-zero field strength can be steered by moving the reflector or by adjusting the amplitude and phase of an additional beam that covers substantially the same region as the main beam reflected by the reflector.