Electro-Optical Transient Protection for Radar Systems
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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 are insufficient in blocking these transients within the first nanosecond.
Innovation Solution
A protection system with a detector and switch network that generates a detection signal upon transient detection, using an electrical-to-optical converter and photoswitch to attenuate or block the transient before it reaches the output, leveraging the propagation delay of an electrical transmission line to ensure the switch activates before the transient arrives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma limiters are used for protection, then protection against electrostatic discharge and near EMP transients is achieved, but the finite turn-on time allows the first nanosecond or more of transients to pass through and damage sensitive electronics
Solution Approach 1:
The patent replaces the electrical plasma limiter system with an electro-optical system. The detector uses an electrical-to-optical converter (such as a light emitting diode) that converts electrical transient signals into optical signals. This optical signal then triggers a photoswitch that rapidly attenuates the transient. The electro-optical conversion enables faster response times, achieving sub-nanosecond protection capability compared to the nanosecond-scale response of plasma limiters.
Solution Approach 2:
The patent introduces an optical intermediary between the detector and the switch. The electrical-to-optical converter transforms the electrical transient into an optical signal that travels through an optical fiber to the photoswitch. This optical intermediary enables isolation between the detection and switching circuits while achieving ultra-fast response times, as optical signals propagate at the speed of light and can trigger the photoswitch before the harmful transient reaches the protected equipment.
2Speed
If a fast switch is used to block transients, then protection speed is improved, but the system complexity increases due to the need for detectors, optical converters, and switch networks
Solution Approach 1:
The electro-optical terminal protection system is designed to protect against multiple types of transients including fast ultra-wideband pulses and high-power microwave signals. The same detector-switch network architecture handles various transient waveforms and frequency ranges, providing universal protection capability. This multi-functionality justifies the system complexity by delivering comprehensive protection across different threat scenarios.
Solution Approach 2:
The protection system is configured to dissipate the energy in the transient without being destroyed, thereby leaving the protection system ready to handle a second transient. The system uses the transient energy itself to drive the detectors and switches, requiring no external power source during operation. This self-service capability simplifies the overall system by eliminating the need for external power supplies and control circuits.
3Speed
If the switch network operates faster than the electrical transmission line propagation delay, then transient attenuation is achieved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent carefully selects and adjusts key parameters including the length and propagation characteristics of the electrical transmission line, the response time of the electro-optical converter, and the trigger sensitivity of the photoswitch. By optimizing these parameters, the system ensures that the switch operates at the precise moment when the transient arrives at the output, achieving effective attenuation without requiring excessively complex control mechanisms or ultra-high-speed components beyond current manufacturing capabilities.
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 attenuates potentially damaging transients, including fast ultra wideband and high power microwave signals, protecting sensitive electronic equipment by dissipating energy without being destroyed, and is capable of handling multiple transients.
Implementation Method 1
The detector is an electrical-to-optical (E-O) converter, such as a light emitting diode (LED), and the switch is a photoswitch that is responsive to the optical signal or light from the E-O converter
Implementation Method 2
the switch is a photoswitch that is responsive to the optical signal or light from the E-O converter
Implementation Method 3
An electrical transmission line is electrically connected between the detector and the switch. The electrical transmission line has an associated propagation delay that is greater than the operating delay introduced by the switch network
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 detector, a switch, and a communication path therebetween. The detector, such as an electrical-to-optical converter, detects a transient at the input 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 switching time of the switch network.