Theoretical Aspects of Microstrip Waveguides

The Microstrip is a modification of the wire-above-ground system of transmission - the wire is replaced by a narrow strip printed on a dielectric sheet which is backed by a conductor. An exact theory for such a structure is difficult because the cross section is not homogeneous and has a geometry which does not lead to separation of variables. Furthermore it is an "open" structure where the energy is not confined to a finite region as it would be in conventional or "closed" waveguides.