Incorporation of edge conditions in moment method solutions

The use of an edge condition in moment method solutions is investigated. Using as an example TM scattering by a strip, various numerical schemes for treating the edge behavior are examined for low frequencies where an analytical solution of the quasi-static integral equation is available for comparison. The same numerical techniques are then applied in the general dynamic case. It is found that failure to incorporate the correct edge behavior in the current expansion can resuit in erroneous currents and anomalous behavior of the solution near edges. The use of ordinary pulses or triangle expansion functions with appropriately singular pulses at the edges circumvents these difficulties. In the case of pulses, a simple correction factor is derived which can be used a posteriori to correct the calculated edge current.