Study of rotationally symmetric antenna with wider beamwidth

Numerical analysis is carried out for the antenna consisting of a rotationa lly symmetric oblate spheroidal conductor connected below and above a circu lar patch antenna with its dielectric substrate truncated at the edges of t he patch. By means of the equivalence principle, the exterior and interior of the antenna are separated as problems equivalent to the original one. Th e cavity model is used for the electromagnetic field model inside the diele ctric material while the equivalent electromagnetic current flows at the di electric aperture are expressed in terms of sums of the mode functions. The current at the conductor surface is assumed from the continuity condition of the current at the junction plane of the dielectric and the conductor. T he magnetic field integral equation at the dielectric aperture and the elec tric field integral equation at the conductor surface are solved by Galerki n's method in order to derive the unknown coefficients contained in the equ ivalent electromagnetic currents at the dielectric aperture and the current at the conductor surface. For the case of a conductor height of 0, a circu lar patch microstrip antenna with its dielectric substrate truncated at the edges of the patch is fabricated and its input impedance is measured. As t he conductor height is increased, the radiation beamwidth in the E plane is expanded. Since this antenna has a wider radiation beam than that of the c ircular patch microstrip antenna, it is useful as an antenna for mobile sat ellite communication terminals. (C) 2000 Scripta Technica.