A hybrid technique for analyzing wire antennas in the presence of a plane interface

A hybrid technique which combines the method of moments (MM) with ray methods is employed to analyze the radiation of wires in the presence of a plane interface. In this technique, which is an extension of that proposed for combining the MM with the uniform geometrical theory of diffraction (GTD), a piecewise sinusoid (PWS) Galerkin method formulation is used. In this paper the basic assumption is made that a PWS dipole can be replaced by three sources of transverse, spherical waves, so that their fields can be treated separately by standard ray methods. Via this procedure the MM matrix can be easily augmented to account for the wire-interface interactions. Calculations of the field both radiated in the antenna half-space and transmitted through a plane interface are found in very good agreement with those performed by using the rigorous Sommerfeld integral representation. These results show that this technique provides an accuracy which is widely acceptable in most engineering applications, even when the wire is placed very close to the interface. This approach, which employs ray methods to calculate reflected and transmitted field contributions, appears promising to treat the case of curved interfaces.