Variance and bias of angle estimation radars

Calculations are presented for the variance and bias of three related angle estimators caused by propagation through a layer containing random index of refraction fluctuations. The usual amplitude and phase sum-and-difference techniques, as well as a third amplitude comparison technique are considered. One-dimensional integral expressions for the variance and bias are given for Gaussian antenna patterns, isotropic turbulence, and targets near the antenna boresights. Results show that for the same total aperture the variances of amplitude and phase comparison monopulse radars are equal for arbitrary turbulence spectrum. The biases for the amplitude and phase sum-and-difference estimators are related by a constant multiplying factor while the bias for the amplitude comparison estimator is generally larger than the bias of the amplitude sum-and-difference estimator.