Stepped Reflector Antenna Gain Variation
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Solution Overview
Problem
Dual-band antenna systems suffer from significant peak-to-edge gain variations in receive beams due to larger reflector sizes, leading to suboptimal performance and gain loss, especially at reception frequencies, while trying to compensate for transmit beams.
Innovation Solution
A stepped reflector antenna design with a central region and an annular region axially stepped to achieve a phase shift of approximately 180° at the outer regions, reducing peak-to-edge gain variations and improving beam patterns without compromising transmit performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the reflector size is increased to improve receive beam coverage, then the coverage area is improved, but the peak-to-edge gain variation increases significantly
Solution Approach 1:
The reflector surface is segmented into multiple zones with different focal points, allowing each zone to be optimized for specific beam requirements while maintaining overall large aperture coverage
Solution Approach 2:
Different regions of the reflector are assigned different focal characteristics - the central region has one focal point while outer annular regions have different focal points, enabling local optimization of gain patterns for different coverage areas
2Reliability
If the reflector is optimized for receive frequencies, then receive beam performance is improved, but transmit beam gain is reduced
Solution Approach 1:
The reflector structure serves dual functions for both receive and transmit operations by incorporating multiple focal points that can be selectively activated depending on the operational mode and frequency band
Solution Approach 2:
The system changes operational parameters by switching between different focal points and feed configurations to optimize performance for either receive or transmit modes at different frequency bands
3Device complexity
If a conventional reflector design is used, then the structure is simple, but gain loss due to pointing error occurs
Solution Approach 1:
The reflector is pre-configured with multiple focal points and zone structures that anticipate and compensate for pointing errors before they occur, allowing the system to maintain optimal gain across varying beam directions
Solution Approach 2:
The system dynamically selects and activates appropriate focal points and feed elements based on the current beam direction and operational requirements, enabling adaptive compensation for pointing 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 reflector design achieves 'flat-topped' receive beams with reduced peak-to-edge gain variations and maintains efficient transmit beam performance, enhancing the overall efficiency of dual-band multiple-beam antenna systems.
Implementation Method 1
The annular region is axially stepped a distance 'h' above or below the central region to achieve a phase shift of approximately 180° at the outer regions
Data Source
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AI summary
A stepped reflector for being illuminated by at least one multiple-band feed is provided. The reflector includes a central region and a first annular region with an annular width of w. The first annular region is axially stepped a height h above the central region, where h is approximately equal to m x [ϕ ± (ϕ (Θ = 0)- ϕ (Θ=Θ0))]x π/180 xλ/2π x 1/2, where m is a positive odd integer, Φ is a desired amount of phase shift of an outer region of a phase front for reflecting off of the reflector, φ is a feed phase contribution for an angle θ, and Θo is an angle formed between an axis of the at least one feed and a line connecting a phase center of the at least one feed and an inner edge of the at least one annular region. The central region and the annular region of the reflector may be parabolically curved or may alternately be shaped. The reflector may be fed by one or more multiple-band horn antennas.