This chapter is aimed at deriving general entire-domain, or almost entire domain, current expansions (in the above sense), following to some extent the method described in References 66 and 67, but also at explaining some subdomain current expansions. It is shown that basis functions can be defined over the surface of arbitrary generalised quadrilateral surface elements that automatically satisfy the continuity equation along the element interconnections and free edges. This is a very important step, which makes most of the methods proposed so far for the analysis of similar structures special, frequently less accurate, cases of the general method proposed here. Specific polynomial expansions will also be elaborated, and their relative advantages with respect to other possible expansions will be discussed.

Inspec keywords: wires (electric); current distribution; polynomial approximation

Other keywords: metallic antenna; arbitrary generalised quadrilateral surface elements; over generalised quadrilaterals; continuity equation; current expansions; current approximation; free edges; generalised wires; polynomial expansions; basis functions; scatterers; element interconnections

Subjects: Wires and cables