MODE-COUPLING IN CORRUGATED WAVE-GUIDES WITH VARYING WALL IMPEDANCE AND DIAMETER CHANGE

Mode conversion due to variation of wall impedance and diameter change in circumferentially corrugated circular waveguides is investigated in this paper. Starting from Maxwell's equations and using vector identities, general simplification integral formulae for coupling coefficients in circumferentially corrugated circular waveguides with both wall impedance and diameter changes are derived. The explicit formulae of corresponding coupling coefficients for any coupled modes are obtained. As a special case of general results, explicit expressions for the coupling coefficients of a tapered smooth-wall waveguide are deduced. The signs of the coupling coefficients in corrugated and smooth-wall waveguides are worked out.