Infinitesimal scaling--A new procedure for modeling exterior field problems

The ability to treat extended uniform linear regions (particularly unbounded external regions) as single elements is a desirable addition to electromagnetic finite element techniques. The use of extended elements requires basis functions that are better approximations to the solutions of the underlying partial differential equations than the conventional polynomial basis functions. This problem can be circumvented by means of the infinitesimal scaling technique, which enables the coefficient matrix required for assembling the contribution of an extended element into the global functional to be determined without explicit knowledge of internal basis functions.