Transient Cerenkov radiation emitted by a pulsed line current traveling above the interface of a two-media configuration

The transient Cerenkov radiation emitted by a pulsed line current traveling above the interface of a two-media configuration is investigated. By using proper transformation variables in the Laplace-Fourier-transform domain we can solve with the aid of the Cagniard-de Hoop method the transient electromagnetic field emitted by a pulsed line current traveling with a speed /spl nu/>0 above the interface of a two media configuration. The Cerenkov radiation which is present when the traveling speed exceeds the wave velocity in the surrounding medium is investigated. In our method the Cerenkov radiation manifests itself in the form of a pole contribution in the complex plane of the spatial Fourier transform variable. Closed form expressions are obtained for the incident as well as the reflected Cerenkov radiation above the interface of the two media. We investigated the case that the traveling velocity exceeds the wave velocity under the interface and the case that the traveling velocity is smaller than the wave velocity under the interface.