CW and pulsed mode transfer impedance measurements in coaxial cables

Transfer impedance measurements have been performed both in frequency and time domains. CW measurements were performed using a matched triaxial system, a quintaxial system, and stripline injection. For nuclear electromagnetic pulse (NEMP) purposes, measurements up to a maximum frequency of 200 MHz are sufficient. For this frequency range the matched triaxial system was found to be the most convenient. Amplitude and phase measurements in different cables are discussed. Direct and indirect injection was employed in the time domain measurements. A delayed coupling is demonstrated when the diffusion term is dominant in the transfer impedance. In a magnetically shielded cable, hysteresis and saturation effects have been observed. At 5 kA the transfer impedance of the magnetically shielded cable increased by an order of magnitude due to saturation