SCHWINGER VARIATIONAL PRINCIPLE CALCULATIONS OF WAVE SCATTERING FROM CONDUCTING CYLINDERS USING PHYSICALLY MOTIVATED TRIAL FUNCTIONS

The Schwinger variational principle for the scattering amplitude is ap plied to two related test problems: an infinitely long perfectly condu cting circular cylinder and a hemicylindrically embossed plane illumin ated by a normally incident plane wave whose magnetic field is perpend icular to the cylinder axis (TM polarization). It is demonstrated that the variational principle yields very good results with trial functio ns containing only a few variational parameters, provided the trial fu nctions mimic not only the correct boundary conditions on the scattere r surface but also the expected shadowing effects of the obstacle. A v ariety of analytical variational limits for both low and high frequenc ies are derived, which, together with the numerical results for interm ediate frequencies, compare very favorably with the available exact so lutions.