with dielectric layers between radiating and capacitor patch
and between capacitor patch and ground plane. The configuration
is defined in Fig. 1. Using the mixed-potential integral expression
scheme of [4], the integral equations are obtained. They are solved
with a moment method procedure. The details of this procedure are
well-known [4]-[7]. It suffices to say that a subsectional expansion
scheme is used combining rooftop functions with the edge expansion
functions of [SI at the edges and in the comers. They satisfy the edge
conditions, which results in an enhancement of the convergence of
the resonant frequency in terms of the number of expansion functions.
It has to be emphasized that, due to the fact that the capacitor patch
is far from its resonance, the use of subsectional expansion functions
is much more efficient than the use of entire domain expansion
functions. The rigorous model described in [4], [9], and [lo] is used
for the coaxial fee