Admittance of insulated loop antennas in a dissipative medium

A small circular loop antenna is located in an insulating layer within a dissipative medium. The admittance of the loop is calculated using a two-term trial function for the loop current in a variational formulation. Thin insulating layers tend to maintain a nearly uniform current around the small loop, in particular for highly lossy surrounding media. The assumption of a uniform loop current is shown to be justified for a range of antenna parameters.