Investigation of the Antenna Factor Behavior of a Dipole Operating Inside a Resonant Cavity

A rigorous analysis of a dipole inside a resonant cavity with wall losses is carried out by solving an electric field integral equation for the current along the antenna. Classic mode expansion is adopted to represent the cavity field, and method of moments is used to achieve the numerical solution of the problem, allowing us to describe the behavior of the antenna parameters in a resonant environment. The theoretical formulation of the problem is applied and validated for a realistic experimental situation, which typically occurs in shielding effectiveness measurements. The analysis focuses on the antenna factor (AF) in order to provide an estimation of the error that is committed when a free-space AF is used for field measurements in resonant structures.