SEM parameter extraction through transient surface current measurement using King-type probes

The well-known miniature loop technique pioneered by R. W. P. King and his co-workers for probing surface currents is considered for the case of measuring transient surface currents-in particular, for the use in performing singularity expansion method (SEM) extraction measurements. The theoretical performance of electrically small loops is reviewed and interpreted in the transient regime. Measured probe responses are presented and viewed against the backdrop of theory. Results are presented for current measurement on a cylindrical scatterer illuminated by a transient spherical wave and compared with numerical predictions. Singularity expansion descriptions extracted from the measured data are presented and ramifications regarding their accuracy and recoverability are discussed.