Time-domain leaky modes on layered media: dispersion characteristics and synthesis of pulsed radiation

In a companion paper (see ibid., p.747-54, June 1993) studying short-pulse radiation from current elements in the presence of plane layered dielectric media, various alternatives for constructing the transient field in terms of spectral-domain wave functions are explored. Two distinctive synthesis options are structured around conventional time-harmonic and nonconventional time-dependent basis wave functions, respectively. To understand the characteristic properties of each, the frequency-wavenumber dispersion relation for the layered environment is explored here in detail. Especially interesting is the behavior of the nonconventional time-domain leaky modes, which exhibit anomalies not encountered in their conventional time-harmonic counterparts. An example is given of how these time-domain modal basis fields synthesize highly resolved short-pulse radiation from a source in a dielectric layer