On the optimum antenna pattern for widebeam radar reflectivity estimation

Noise is a limiting factor in radar systems. The power received from a target depends on the target reflectivity varying with the aspect angle, the target range and the antenna pattern, amongst others. Inevitably, an estimation algorithm for the mean target reflectivity weights noise contributions from greater aspect angles stronger than such from smaller aspect angles due to the target range increasing with increasing aspect angle. However, as an opposed effect, due to the supposed equidistant rather than equiangular sampling along the linear aperture, noise contributions for greater aspect angles have lower influence than those for smaller aspect angles. In the paper, the signal-to-noise ratio for a linear, equidistantly sampled aperture and an arbitrary antenna pattern is determined. Moreover, an upper limit for the achievable signal-to-noise ratio is given, and the antenna pattern maximizing the signal-to-noise ratio is derived.