Inadequacies of collocation solutions to Pocklington-type models of thin-wire structures

Two shortcomings of the use of collocation method of moments procedures to solve Pocklington-type integral equations for thin-wire structures are discussed. One of the shortcomings, innate in the collocation procedure, is that match-points cannot be spaced sufficiently densely in the feed region of a wire antenna to accurately sample the highly local driving field when the feed diameter is very small The other shortcoming occurs when the current, expressed as a linear combination of the elements of the basis set, exhibits slope discontinuities. The behavior of the scattered field computed from such currents is discussed in terms of its influence on solution convergence. The results of numerical experiments embodying these two phenomena are presented.