Diffraction of an electromagnetic signal on an ideally conducting cone with a dielectric coating

Abstract

The paper examines the scattering of a Gaussian video signal by an ideally conducting circular cone coated with a dielectric layer. The problem is solved by the method of integral equations for monochromatic waves at low and resonance frequencies with subsequent Fourier transformation to the time domain. The response is investigated with signals propagating along the symmetry axis from the direction of the apex and from the direction of the base for dielectric layers of various permittivities.The development of video pulse radar has stimulated theoretical research on the diffraction of nonstationary electromagnetic signals on various bodies. This body of research has been based on time-domain integral equations (TDIE) for currents induced on the surface of an ideally conducting scatterer [1,2]. TDIE have been solved numerically using various approximations in time and in space. The body surface is partitioned into elements and the current is determined at the center of each surface element as a function of time. In this setting, we can in principle solve diffraction problems on bodies of an arbitrary shape. This approach, however, involves large RAM requirements, because we need to save currents and their derivatives at each time instant. For axially symmetric bodies, the currents can be expanded in Fourier series in the azimuthal coordinates, and information about the Fourier coefficients for the currents and their first derivatives needs to be saved only at selected points of the generatrix, and not on the entire surface. This results in an essential saving of computer memory [3].Such a TDIE algorithm for dielectrics or dielectric-coated ideally conducting bodies is extremely difficult to implement at present. TDIE are quite complex, specifically due to the presence of second time derivatives of currents. Recall that integral equations for ideally conducting bodies contain currents and their first time derivatives only.There is an alternative approach to investigating the scattering of nonstationary signals. It solves the diffraction problem of a monochromatic wave in the frequency domain and then applies the inverse Fourier transform to pass to the time domain. This approach has been used to investigate the scattered nonstationary signal on an ideally conducting finite circular cone [4,5] with the primary wave propagating along the cone axis. The frequency dependences for inverse scattering used in these