Corrugated horns: Computer analysis of input impedance properties and of mode excitations

To minimize input reflection and excitation of unwanted modes in corrugated feeds, the most critical point is the transition between the guide with smooth wall and the one with corrugated wall. This junction has been theoretically examined by assuming impedance boundary conditions in the corrugated region. The Wiener-Hopf technique leads to an exact solution of this canonical problem and yields modal coupling coefficients. A set of numerical results is presented for different ratio between the inner and the outer radii of the corrugated guide.