New variational principle in electromagnetics

A new variational principle that applies to a wide class of electromagnetic problems is presented. This principle has the distinctive characteristic of always producing linear algebraic equations when the Rayleigh-Ritz procedure is applied using a trial field composed of a linear combination of variational parameters. The new technique is applied to a general class of antenna problems, and is specialized to the case of a dielectrically coated slot antenna. Experimentally observed admittance values at band are presented and compared with theoretical predictions.