An approximate solution for E-polarization coupling into a coaxial cylinder with an infinite axial slot

An approximate solution is derived for determining the total current induced on a centrally located conducting wire within a two-dimensional axially slotted cylinder for the case of E-polarization. Its validity is tested against a full moment-method numerical solution of the describing integral equation. The derivation of the approximate solution is similar to the hollow-cylinder case presented by P.M. Morse and H. Feshbach (195) in that the same basic form for the aperture distribution is assumed. A rapidly converging series solution is developed which is shown to be valid for an electrically `narrow´ slot (accurate for apertures up to one wavelength wide) over a rather broad frequency spectrum. Though the aperture must be electrically narrow, many practical coupling problems of interest can be accommodated. Useful insight into coupling phenomena is obtained by direct inspection of the solution, and some novel observations about the current response are made