Calculation, Simulation, and Measurement of Input Impedance and RF-Induced Current of Bridgewire Electro-Explosive Device

Abstract

The input impedance of bridgewire electro-explosive devices (BW EEDs) is a key parameter for quantifying their response to electromagnetic (EM) radiation (EMR). However, the calculation process is brief and lacks verification. In addition, the radio frequency (RF)-induced current of BWs is usually approximated to that of EEDs, but the applicability still lacks validation. In this article, the input impedance of a BW EED is calculated and simulated. Using the analytical or simulated circuit model of the BW, the calculated input impedance is close to the simulated result. The measured and simulated input impedances are in good agreement. Subsequently, the Norton equivalent circuit of the connecting wires of the EED exposed to EMR is determined. After that, the induced currents of the EED and the BW are calculated using the equivalent circuit method. Then, the simulation is performed to calculate the induced current of the BW to validate the currents using the circuit model. The currents of the BW and the EED are close to the simulated result in 1–7 GHz. However, in about 7–11 GHz, there are obvious deviations between the currents, which may result from the impedance mismatch and coupling EM energy of the transmission line of the EED. The current of the BW is measured, verifying the simulated result. The influences of the aperture angle formed by the connecting wires, the polarization, and the incidence direction of EM wave on the induced current are studied using the simulation. When the aperture angle is 90°, the induced current of the BW is highest. The induced current decreases as the polarization angle increases. The influence of incidence direction on induced current depends on the antenna radiation pattern.