An experimental investigation of the King surface current probing technique in a transient application

An experimental technique to measure transient surface currents of a scatterer using a King-type semicircular miniature probe is reported. The principal extension of the King technique is the use of the loop probe in transient currents measurement. The transient characteristics of the probe are considered based on the Whiteside theory (29) for the loop. The probes fabricated were subjected to transient excitation in a coaxial calibration jig. Their frequency responses were determined by Fourier transforming their output and deconvolving the excitation spectrum. The agreement between the measured results and the Whiteside theory is observed and evaluated. The probe geometry was tested in an application context, namely, the probing of current on a cylindrical scatterer. The induced surface currents were measured using the probe along the scatterer, and deconvolution of the probe transfer function was carried out subsequently. The deconvolved waveforms are reported and the results of numerical predictions by way of a time domain integral equation technique are reported for comparison. The application goal for this work lies in the numerical extraction of the Singularity Expansion Method (SEM) description of scattering from a given object, using measured transient data.