Electric Field Radiated in the Air by a Dipole Antenna Placed Above a Two-Layered Lossy Half Space : Comparison of Plane Wave Approximation with the Modified Image Theory Approach

摘要

The paper deals with the calculation of electric field radiated in the air by a dipole antenna placed above a lossy half space modelled as a two layered medium. The frequency domain formulation for the unknown current along the wire is based on Pocklington's integro-differential equation solved using the Galerkin Bubnov scheme of Indirect Boundary Element Method (GB-IBEM). The current is inserted into field formulas governing the field distribution in the air. The presence of the three medium configuration, air-layer1-layer2, is taken into account by two approaches. The first one is the Fresnel's approximation for the reflection coefficient, which beside the electric properties of the media, accounts for the incidence angles at the interfaces. On the other side, the Modified Image Theory (MIT) based approach assumes the normal incidence which simplifies the calculation of the reflection coefficient. Comparison of the two approaches in frequency domain undertaken in this work serves as a benchmark for the future time domain modelling of multilayered subspaces which is more cumbersome and MIT based approach may seem as a plausible approach.