Dyadic Green's Function Formalism for Electromagnetic Detection in Layered Media

The authors previously introduced a formalism for detecting objects through a complex dielectric interface using dyadic Green's functions. This formalism improved upon existing approximations for the electromagnetic fields generated by and onto canonical structures such as loops and dipoles. However, targets of interest are not loops or dipoles but rather irregularly shaped structures. Using inadequate antenna models to represent complex targets can lead to signal-to-noise ratio uncertainties greater than 10 dB, often unacceptable for target detection. Restructuring the formalism has yielded relatively simple expressions for targets embedded in the same complex dielectric as the sensor, those at the dielectric interface, and those on the other side of the interface. The approach ensures that the hard part of the problem, calculations in the complex plane, need be done only once. Differences in the probability of detection are shown to be traceable to the radiation vector of a target in the same dielectric or to an equivalent target representation either at the dielectric interface or on the opposite side. In all three cases, these latter calculations are straightforward. The authors examine detection over a conducting surface with an embedded target. Results for simple and complex target geometries illustrate the power of the method.