Field radiated by a leaky-wave slot fed by dipole: ray description

The magnetic current excited by an electric dipole on a slot printed between two different homogeneous media has been derived in analytical form under the non restrictive assumption of small slot width in terms of wavelength (see Neto, A. and Maci, S., Technical Report No D/21321, California Institute of Technology, Jet Propulsion Laboratory). We continue the investigation on this topic providing a ray description of the field in the denser medium. Although general concerns about the Green´s function of open waveguiding structures have been addressed by other authors in a more general framework (see Di Nallo, C. et al., 1998; Mesa, F. et al., 1999), the investigation presented here assumes importance because of the closed form expressions which simplify the understanding of the physical mechanisms. Our ray field representation is similar to the one presented by F. Villegas et al. (see IEEE Trans. on Microwave Theory and Techniques, vol.47, no.4, p.443-53, 1999) for the case of a semi-infinite microstrip fed by a quasi TEM mode. In a companion paper (see Maci and Neto, ibid., p.494-7), a uniform asymptotic evaluation is performed, thus giving more insight into the leaky wave-space wave transition process.