Resonator-Coupled RF Limiter for Selective Jam Suppression
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Solution Overview
Problem
Frequency selective limiters (FSLs) face challenges in effectively attenuating high-power jamming signals while allowing lower power signals with small frequency offsets to pass through, particularly in RF systems like GPS receivers, where non-linearities in broadband receivers cause inter-modulation and spurious signals, obscuring signals of interest.
Innovation Solution
A frequency selective limiter system incorporating a pair of back-to-back diodes coupled with a resonator, where the resonator is tuned to specific frequencies to attenuate signals above a threshold value only if they match the resonator's frequency, allowing off-resonance signals to pass through, thereby enhancing dynamic range and reducing unwanted interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a frequency selective limiter uses non-linear excitation of spin waves in YIG film to attenuate high-power signals, then jamming signals are suppressed, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the frequency-selective limiting function from complex YIG film spin wave mechanisms and implements it using a simple resonator circuit with diodes. The resonator is tuned to specific frequencies to provide selective attenuation, while the diodes handle the non-linear power limiting, separating these functions into simple, manufacturable components rather than requiring complex magnetic material structures.
Solution Approach 2:
The patent replaces the mechanical/magnetic system (YIG film spin waves) with an electrical system (resonator circuit with diodes). This substitution maintains the frequency-selective power limiting function while dramatically simplifying manufacturing, as electrical components can be more easily fabricated and integrated into RF circuits compared to precision magnetic film structures.
2Duration of action of moving object
If a frequency selective limiter attenuates high-power jamming signals, then the dynamic range is improved, but loss of lower power signals with small frequency offsets increases
Solution Approach 1:
The patent applies local quality by making the attenuation characteristic frequency-dependent through the resonator tuning. The resonator is designed to resonate at specific jamming frequencies, providing strong attenuation only at those frequencies while maintaining low insertion loss for all other frequencies. This localized frequency-selective attenuation protects against jamming while preserving legitimate signals with small frequency offsets.
3Adaptability or versatility
If broadband receivers operate with high dynamic range requirements, then interference signals are captured, but non-linearities cause inter-modulation and spurious signals
Solution Approach 1:
The patent applies preliminary action by placing the frequency selective limiter before the broadband receiver to pre-process the incoming RF signals. The limiter performs power conditioning and frequency-selective attenuation on strong interferers before they enter the receiver, preventing the receiver's non-linearities from generating inter-modulation products and spurious signals, while allowing the receiver to maintain its broadband capability.
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 system effectively increases the dynamic range of RF receivers by selectively attenuating high-power signals while allowing lower power signals to pass, improving the signal-to-noise ratio and reducing spurious signals, thus enhancing the anti-jam performance and operational linearity of RF systems.
Implementation Method 1
a resonator. The resonator is coupled to the pair of back-to-back diodes
Implementation Method 2
A frequency selective limiter includes a pair of back-to-back diodes, coupled to an input and an output of the frequency selective limiter
Data Source
AI summary
A frequency selective limiter includes a pair of back-to-back diodes, coupled to an input and an output of the frequency selective limiter, and a resonator. The resonator is coupled to the pair of back-to-back diodes.