PLANAR NEAR-FIELD SCANNING IN THE TIME-DOMAIN .1. FORMULATION

Time-domain planar near-field measurement techniques are formulated for acoustic and electromagnetic fields. Probe correction is ignored in that it is assumed that the probe measures the exact values of the field on the scan plane. Two fundamentally different approaches are used in deriving three sets of formulas that give the fields in the source-free half space z > z0, in terms of their values on the scan plane z = z0. In the first approach the time-domain formulas are obtained by inverse Fourier transforming the corresponding frequency-domain formulas. In the second approach the time-domain formulas are derived directly in the time domain by working with time-domain Green's functions. A companion paper (Part 2) presents the time-domain sampling theorems and computation schemes necessary for the implementation of time-domain planar near-field measurements.