Scattering from loaded narrow grooves and slits in thick conducting plates

The authors derive analytical expressions for the equivalent magnetic current distributions over the apertures of material-filled narrow grooves and slits based on a quasi-static approximation of the pertinent integral equations. The solutions exhibit the expected edge behavior at the terminations and are used to find closed-form expressions for the echo-width of the groove. Both transverse electric (TE) and transverse magnetic (TM) polarizations are treated. The derived analytical expressions for the equivalent currents are of potential importance in constructing suitable models for long and narrow three-dimensional apertures.<>