On improving the surface wave efficiency of microstrip patches

Printed antennas manufactured on high, rather than low, relative permittivity substrates typically exhibit a lower surface wave efficiency. Jackson et al. (1993) proposed two novel circular printed antennas which weakly excited a surface wave mode. The resulting configurations, although larger and somewhat more difficult to fabricate than a more conventional microstrip patch antenna, improve the surface wave efficiency of the radiating element considerably. In this paper, two other geometries are considered which can improve the surface wave efficiency of a radiating element while making the element construction comparable to a conventional printed antenna. These elements are examined using a full-wave spectral domain Green's function/Galerkin technique. Both the advantages and the drawbacks ofthe geometries are addressed.