The geometry of a rectangular microstrip antenna fed by an openend
coplanar waveguide is shown in Fig. 1. We assume that the
substrate and the ground plane extend to infinity in the x and y
directions and that the conductors are perfectly conducting and of
negligible thicknesses. The coordinates are chosen such that the
ground plane coincides with the zy-plane, the coplanar waveguide
is symmetric about the z-axis, and the y-axis is placed along the
edge of the end of the coplanar waveguide. To simplify the analysis,
the patch is also placed symmetric about the z-axis; nevertheless,
our theory can easily be modified to allow asymmetric placement of
the patch