Robust spectral-domain EM modeling of distributed-source sensors in planar-layered media

We report a rapid, robust full-wave methodology to model electromagnetic (EM) wave radiation by distributed current sources embedded in planar-layered media. Primitive causality-related numerical instabilities within the computation chain, induced by exponentially rising "distributed" current source spectrum functions, are addressed for both linear and aperture sources, leading to solution speed acceleration between one and two orders of magnitude versus space-domain superposition of Hertzian dipole fields. To overcome the instabilities, prior to numerical evaluation one analytically identifies and merges all exponentially rising and decaying terms, yielding an overall well-convergent and stable solution process. We present numerical results concerning sensors used to detect marine hydrocarbon reserves.