Resistive Frequency Selective Surface for Radar Coupling Reduction
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Solution Overview
Problem
Antenna systems experience unwanted coupling and electromagnetic interference due to the proximity of transmit and receive modules, leading to performance degradation, especially at extreme scan angles, and existing solutions like R-cards and magnetic absorbers are ineffective in reducing interference while maintaining system performance.
Innovation Solution
Incorporating a tunable resistive frequency selective surface circuit within or near the radome to act as a directional filter, attenuating unwanted signals while allowing desired signals to pass through, thereby reducing electromagnetic interference and improving system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If R-cards are placed near transmit and receive modules to reduce coupling and electromagnetic interference, then interference reduction is achieved, but radome loss increases and perpendicular scan behavior deteriorates
Solution Approach 1:
The resistive frequency selective surface circuit is selectively positioned only in regions where coupling and electromagnetic interference are most severe, rather than uniformly distributing R-cards throughout the radome. This localized approach provides interference reduction where needed while minimizing overall impact on radome performance and scan behavior
Solution Approach 2:
The invention uses frequency selective surface circuits with specific resonant frequencies and impedance characteristics tailored to the operating band, replacing broadband R-cards. This allows selective attenuation of interfering signals at specific frequencies while maintaining better radome loss characteristics and scan performance
2Loss of energy
If R-cards with high impedance are used to address radome loss and scan behavior degradation, then insertion loss improves, but attenuation per distance becomes insufficient
Solution Approach 1:
The invention combines resistive materials with frequency selective surface patterns to create a composite structure that provides both the impedance matching benefits of high-impedance materials and the frequency-selective attenuation of FSS circuits, achieving both low insertion loss and high attenuation of coupled signals
Solution Approach 2:
The frequency selective surface circuit acts as an intermediary between the transmit and receive modules, providing frequency-selective attenuation of coupled signals while maintaining a more favorable impedance profile than traditional R-cards, thus reducing both insertion loss and coupling simultaneously
3Object-affected harmful factors
If magnetic absorbers are used to reduce electromagnetic interference, then interference attenuation is achieved, but system weight increases and high frequency performance deteriorates
Solution Approach 1:
The invention replaces magnetic absorber materials with resistive frequency selective surface circuits that achieve electromagnetic interference reduction through resonant circuit mechanisms rather than magnetic loss, eliminating the need for heavy magnetic materials while maintaining effectiveness at high frequencies
4Object-affected harmful factors
If R-cards are placed to reduce coupling, then interference is attenuated, but performance at extreme scan angles deteriorates
Solution Approach 1:
The frequency selective surface circuit is positioned and oriented to provide selective attenuation only in the regions and directions where coupling occurs, preserving the radome's ability to maintain consistent performance across all scan angles including extreme angles
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 resistive frequency selective surface circuit effectively reduces unwanted coupling and electromagnetic interference, enhancing radar system performance by minimizing energy loss and maintaining gain, especially at extreme scan angles, while optimizing frequency and scan requirements.
Implementation Method 1
a resistive frequency selective surface circuit configured to reduce a coupled portion of the signal
Implementation Method 2
The resistive frequency selective surface circuit may also include a thin film resistor material
Data Source
AI summary
An antenna system for reducing unwanted coupling and electromagnetic interference, the antenna system including a transmit module configured to send a signal, a receive module configured to receive the signal, a radome, and a resistive frequency selective surface circuit configured to reduce a coupled portion of the signal, the resistive frequency selective surface circuit disposed in a path of the coupled portion of the signal.