A method for computing the electromagnetic response of resonant composite structures comprising metallic and dielectric elements enclosed by a dielectric shell

Unmanned aerial vehicles (UAVs) of various classes include metallic and dielectric structural elements whose dimensions are comparable to wavelengths in the meter and decimeter range, making them resonant-sized objects. To improve the quality of radar surveillance of such objects, it is necessary to have a priori information about their secondary radiation. This paper proposes a method for calculating the electromagnetic response of resonant composite objects enclosed in a dielectric shell, taking into account the interaction between internal metallic and dielectric components. To compute the electromagnetic field scattered by an electrically large dielectric shell, an asymptotic high-frequency method is applied. To evaluate the secondary radiation characteristics of the internal metallic and dielectric elements, considering their mutual interactions, a computational approach based on an iterative electrodynamic integral equation method is used. The primary field for the internal resonant-sized components is assumed to be the electromagnetic field transmitted through the dielectric shell. An algorithm for computing the electromagnetic response of such composite objects has been developed. This algorithm integrates two electrodynamic methods: the asymptotic high-frequency method and the iterative method of integral equations. A distinctive feature of the algorithm is that the interaction between the thin dielectric shell and the internal metallic and dielectric components is considered both at the initial stage—when forming the primary incident field transmitted through the shell—and at the final stage—when the electromagnetic field from the internal components propagates to the receiving point, again passing through the shell. The algorithm enables the computation of radar cross-sections (RCS) of realistic radar targets of various shapes and materials for different radar probing scenarios. Future research will focus on developing surface models of actual radar targets with internal metallic and dielectric elements and obtaining reliable a priori data on their detectability under varying illumination and polarization conditions of the incident electromagnetic wave.