N.I. Voytovich, D.S. Klygach, A.B. Khashimov

The paper proposes the rigorous electromagnetic method for calculation of the bilateral slot antenna field in far zone. The bilateral slot antenna is performed on open perfectly conducting surface, which is bounded by arbitrary shape contour. It is assumed that the thickness of the surface strive for zero and surface satisfies the Lyapunov-s condition which requires continuity of the surface's normal vector at any point. The Lorentz lemma for connecting far-field of the bilateral slot antenna and radiation field of the auxiliary magnetic dipole is used for obtaining basic formulations. The Green-s function, which corresponds to this source, can be represented as a sum of plane wave field and scattered field of the continuous surface without slot. Invariance of both location and polarization of the auxiliary dipole provides to separate two field's components out of the general solution, which determines the bilateral slot antenna's far-field pattern in given coordinate planes. The pattern asymptotic representation is based on analysis of the integral stationary values over a large radius surface and gives formulas to calculate the bilateral slot antenna radiation field. These formulas have a clear physical meaning. If scattered field (caused by a plane wave acting upon the continuous surface from any direction) is known, then it is possible to obtain the bilateral slot antenna's pattern value for this direction as a result of integration the difference of the magnetic field vectors' limit values on opposite sides of the surface where the sources as magnetic currents are disposed. We assume that the coordinates of these sources strives to surface. The exciting functions of the sources operates as weight coefficients for integral expressions. On the basis of these expressions is possible to introduce the «reaction» functionals to calculate the pattern for thin slot antenna, which is performed on extended constant-width band. For numerical solution this 3D vector problem can be reduced to more simple scalar 2D problem. Correctness of this assumption is confirmed by the results of numerical solution of the corresponding integral equations.