P-adaptive finite element analysis of unbounded electromagnetic wave problems

The boundary that artificially truncates an unbounded domain in the finite element analysis of an electromagnetic wave problem necessarily introduces a numerical error. The adaptive technique proposed reduces this boundary error, as well as the usual finite element discretisation error. The scattering or radiating object and its immediate surroundings are meshed with hierarchal finite elements. Outside, a thick layer of free space is meshed with relatively few hierarchal wave-envelope elements. During p-adaption, increasing the order of the wave-envelope elements reduces the boundary error. Moreover, this reduction in boundary error is selective: in directions of strong radiation, the error reduction is greater.