Electro-Optic Transient Protection System with Quarter-Wave Stub
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Solution Overview
Problem
Directed energy weapons, such as fast ultra wideband pulses and high power microwave signals, can cause transients that damage radar systems, and existing nonlinear protection elements like plasma limiters have a finite turn-on time, failing to block the initial nanoseconds of these transients.
Innovation Solution
A protection system with a detection mechanism that generates a signal to operate a fast switch, attenuating or blocking transients before they reach sensitive electronic equipment, using a quarter-wave stub for impedance matching and optical-electrical converters with photoswitches to manage the signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nonlinear protection elements like plasma limiters are used, then protection against electrostatic discharge and near EMP transients is achieved, but the finite turn-on time fails to block the first nanosecond or more of transients from directed energy weapons
Solution Approach 1:
The patent replaces the mechanical/physical plasma limiter system with an electro-optic detection and control system. The system uses an electro-optic converter to detect transients and triggers a photoswitch to block the signal, substituting the passive plasma-based protection with an active electronically-controlled optical switching mechanism that achieves faster response times capable of blocking sub-nanosecond transients
Solution Approach 2:
The patent introduces an optical intermediary (optical fiber) between the detection point and the switching element. The electro-optic converter detects the transient and sends an optical signal through the fiber to trigger the photoswitch, creating a decoupled detection-control pathway that enables faster and more reliable transient blocking compared to direct electrical connection systems
2Difficulty of detecting and measuring
If a detector is connected directly to the transmission line, then transient detection is achieved, but impedance mismatch occurs because the detector has lower impedance than the transmission line
Solution Approach 1:
The patent introduces a quarter-wave stub as an impedance-matching intermediary between the transmission line and the detector. The stub, being a quarter-wavelength transmission line section, transforms the impedance to enable proper matching between the high-impedance transmission line and the low-impedance detector, minimizing signal reflections and insertion loss while maintaining detection 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
Effectively blocks or attenuates potentially damaging transients, including fast ultra wideband and high power microwave signals, protecting sensitive equipment by dissipating transient energy without being destroyed, and is capable of handling multiple transients.
Implementation Method 1
The quarter-wave stub is an impedance matching device between the input and the detectors
Implementation Method 2
The detector is an electrical-to-optical (E-O) converter, such as a light emitting diode (LED)
Implementation Method 3
the switch is a photoswitch that is responsive to the optical signal or light from the E-O converter
Data Source
AI summary
Apparatus for protecting a device from transients. The apparatus includes a switching network and a transmission line electrically connecting an input to an output. The switching network includes a stub connected near the input with a detector at the other end, a switch, and a communication path therebetween. The detector detects a transient and communicates with the switch. The switch then actuates to place a low impendence across the output of the transmission line, thereby attenuating the transient. The switching network has a switching time that equals the sum of the times to detect the transient at the input, transmit a signal corresponding to the detection to the switch, and actuate the switch. The input signal travels from the input to the output along the transmission line, which has a propagation delay. The propagation delay is greater than the stub propagation time plus the switching time of the switch network.