Coplanar Waveguide Plasma Limiter for High-Power RF Protection
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Solution Overview
Problem
Diode limiters are ineffective in handling high power levels, which can damage sensitive RF circuits during adversary jamming or ally co-site transmission, necessitating a more robust power limiting solution for RF transmission lines.
Innovation Solution
A radio frequency (RF) transmission line with a coplanar waveguide structure incorporating a plasma limiter that forms a spark-gap between the signal and ground lines, generating plasma at a controlled power threshold to alter the characteristic impedance and limit power transmission, thereby protecting sensitive electronics from excessive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diode limiters are used to protect RF circuits, then power limiting function is provided, but the device cannot handle very high power levels
Solution Approach 1:
The patent changes the physical state of the gas in the spark-gap from non-ionized to ionized (plasma) at high power levels. By adjusting gas pressure and spark-gap geometry, the device achieves breakdown at specific power thresholds, enabling it to handle very high power levels while providing effective power limiting protection for RF circuits.
Solution Approach 2:
The invention utilizes the phase transition of gas to plasma through electrical breakdown in the spark-gap. This phase transition occurs at high power levels and creates a low-impedance path that reflects excess power, allowing the device to handle power levels beyond the capability of conventional diode limiters while maintaining protection functionality.
2Power
If plasma limiter with spark-gap is used, then high power handling capability is achieved, but device complexity increases
Solution Approach 1:
The patent integrates the plasma limiter directly into the coplanar waveguide transmission line structure, merging the power limiting function with the signal transmission path. The spark-gap is formed between existing signal and ground lines, eliminating the need for separate limiter components and reducing overall device complexity despite the advanced functionality.
Solution Approach 2:
The plasma limiter operates autonomously based on the incident RF power level. When power exceeds the breakdown threshold, the gas automatically ionizes and reflects excess power without requiring external control circuits or additional components, thereby achieving high power handling capability with minimal added complexity.
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 plasma limiter effectively limits power transmission to sensitive RF equipment by reflecting excessive power back to the source, while maintaining low insertion loss and protecting the equipment from damage, with the ability to handle higher power levels than diode limiters.
Implementation Method 1
a breakdown power threshold at which the gas disposed in the spark-gap forms a plasma
Implementation Method 2
the gas disposed in the spark-gap forms a plasma
Implementation Method 3
The plasma limiter effectively limits power transmission to sensitive RF equipment by reflecting excessive power back to the source
Data Source
AI summary
A radio frequency (RF) transmission line is described. The RF transmission line includes a first ground line, a second ground line, and a signal line disposed on a substrate and forming a coplanar waveguide. A plasma limiter feature is integrated into an internal surface of one or more of the first ground line, the second ground line, and the signal line. The plasma limiter decreases a gap distance between the signal line and the associated ground line. The gap distance is selected, together with a gas pressure, to control a voltage at which the gas within the gap breaks down, targeted at a breakdown power of 1 W across a wide bandwidth. The plasma limiter thus limits a power transmitted by way of the RF transmission line for protecting a sensitive integrated circuit.