Semi-Analytic Solution to Forward Scattering From a Long Conductive Strip

A semi-analytic model is developed that accurately describes the scattered electromagnetic field (including both reflection and diffraction) from a long conductive strip, which is on the order of a wavelength wide. When the dimension of this conductor is on the order of a wavelength, the gross approximations used for ray-tracing models cannot be used, because the scattering object does not satisfy the assumption that it is electrically large, resulting in a vanishing wavelength. Unlike ray-tracing techniques, this model completely describes the field diffracted around and behind the conductive obstruction, creating the null that is commonly called the “shadow” from an illuminated object. The only assumption made is that the strip is relatively long, compared to its width and to the wavelength. When simulations from this analytic model are compared to simulations from an established numerical model, it is found that this analytic model provides accuracy comparable to numeric methods, without the extensive computational intensity involved in numerical solutions. Furthermore, simulated field patterns from this analytic diffraction model are compared to 2-D measured patterns, resulting in close agreement.