Low-Frequency Limit of Unified Models for Backscattering From Oceanlike Surfaces

In the context of electromagnetic-wave backscattering from oceanlike surfaces, by using the first two orders of unified models, like the small slope approximation and the local curvature approximation, we recently proposed an original technique to reduce the number of numerical integrations to two for easier numerical implementation. In this letter, this technique is simplified in the low-frequency limit, allowing us to bring a correction to the first-order small perturbation method.