WKB Across Caustics: The Screened-WKB Method

We present a new methodology, based on the WKB approximation and Fast Fourier Transforms, for the evaluation of wave propagation through inhomogeneous media. This method can accurately resolve fields containing caustics, while still enjoying the computational advantages of the WKB approximation, namely, the ability to resolve arbitrarily high-frequency problems in computing times which are orders-of-magnitude shorter than those required by other algorithms presently available. For example, the proposed approach can simulate with high accuracy (with errors such as e.g. 0.1\%--0.001\%) the propagation of 5 cm radar signals across two-dimensional configurations resembling atmospheric ducting conditions, spanning hundreds of kilometers and millions of wavelengths in electrical size, in computing times of a few minutes in a single CPU core. [Preliminary version]