Calculation of currents induced in a long transmission line placed symmetrically inside a rectangular cavity

In this paper electric field coupling to a transmission line located symmetrically inside a rectangular cavity is investigated. The applied distributed fields have different origin: Firstly, one field is generated inside the cavity by a small electrical antenna, and secondly, the other field stems from a plane wave which couples through a circular hole into the cavity. In every case the respective field contributes to the induced current on the line. The line is treated in the thin-wire approximation and the induced currents are calculated at the terminations of the wire. Two methods are applied to obtain the currents: an analytical method and a numerical package using a MLFMM-procedure. The comparison of both results shows good agreement. The advantage of the analytical calculation is the much shorter.