Novel microwave network for the leaky-wave analysis of evanescent fields in stub-loaded structures

In this paper, a new transverse equivalent network for the modal analysis of stub-loaded leaky-wave antennas is developed. The derived network is useful for the study of the radiation of evanescent fields that occurs when they reach the top aperture of the parallel-plate stub. This transverse network is based, for the first time, on a nonhybrid formulation of the constituent parallel-plates modes of order 1 ([TE.sup.Z.sub.1] and [TM.sup.Z.sub.1]). The obtained network is an alternative to the one based on hybrid [TE.sup.Y.sub.1] and [TE.sup.Y.sub.1] modes, and leads to a simpler transverse resonance equation. The new equivalent network is validated by obtaining leaky-mode dispersion curves for a previously studied leaky-wave antenna in nonradiative dielectric guide technology. Index Terms--Nonradiative dielectric (NRD) leaky-wave antennas, stub-loaded leaky-wave antennas, transverse equivalent circuit.