A NEW METHOD OF SOLUTION OF HALLENS PROBLEM

A wide class of electromagnetic scattering problems can be expressed a s a system of dual integral equations. This kind of integral equation, occurring in boundary value problems wherein there is one equation fo r a certain region and another for the dual domain, is usual in diffra ction problems. Considerable attention has been drawn by many research ers in the field of optics, acoustics, scattering of elastic waves, ac celerator physics, and antenna theory. Wiener-Hopf techniques enable u s to solve such kinds of integral equations when the two regions are c ontiguous and semi-infinite. Unfortunately Wiener-Hopf techniques do n ot apply if one of the regions is finite; this is the case for realist ic scatterers, such as irises, antennas, and drift tubes in accelerato rs. In this article a general method for solving such dual integral eq uations is discussed and applied to a particular case: Hallen's equati on of cylindrical antennas. This method consists of a transformation o f the dual integral equations into a Fredholm integral equation of the second kind and then into a linear system of algebraic equations. Com parisons with results obtained by other methods for a wide range of fr equencies show the accuracy and the robustness of the proposed one. (C ) 1995 American Institute of Physics.