A VOLUME AND SURFACE SOURCE INTEGRAL FORMULATION FOR ELECTROMAGNETIC SCATTERING FROM PRINTED-CIRCUIT ANTENNAS

In recent years, printed circuit antennas have become very useful in phased array antennas. These antenna array-elements consist of three-dimensional distributions of dielectric substrates and conductors. An explicit model of these microstrip and strip-line element geometries is needed for predicting their radiation and scattering characteristics. The near electric field of a dielectric body is primarily produced by the bound charge residing on the surface. An accurate near field model is obtained through the use of this bound charge density. The polarization current induced in the dielectric is expanded in terms of divergence-free expansion functions which produce surface change doublets. An integral equation is obtained where differentiation in the scalar potential term is avoided through use of a vector identity, the equation of continuity, and the divergence theorem. This paper presents a volume integral formulation in conjunction with a method of moments solution for electromagnetic scattering from two- and three-dimensional homogeneous dielectric printed circuit substrates. The theory for printed circuits consisting of dielectric substrates and conducting surfaces is also presented. The TE scattering from a dielectric cylinder and a dielectric sheet are computed and compared to other numerical results. The results for electromagnetic scattering from a three-dimensional dielectric cube are also shown and compared to other results.