Mutual impedance of linear antennas in the presence of a stratified dielectric

Abstract

Two linear flat strip antennas lie in an interface between several dielectric layers. The mutual and self-impedance of the antennas is computed, based on a variational formulation of the antenna impedance with symmetrical and antisymmetrical excitation conditions. For free space surrounding the antennas, the present variational formulation provides a closer agreement with measurements than past solutions of the iterative type. For antennas in a dielectric slab, the mutual impedance is shown to be increased by increasing electrical thickness of the layer, but decreased by increasing dielectric losses. The present calculations tend to agree with transmission line approximations of the antenna impedance for insulated antennas in a highly lossy medium, but the two sets of calculations differ for small antenna separations and for lower dielectric losses, in particular if the permittivity of the lossy medium is also lower.