Efficient simulation of radiometric noise in offset Gregorian antenna systems

A comparative study of different models to calculate the radiometric noise in an offset Gregorian antenna system is presented. Some convergence studies on the radiometric noise integral are performed, and the required radiation pattern grid densities are deduced. A simplified brightness temperature model is suggested and evaluated, and the model is shown to produce accurate results at the lower microwave frequencies. The accuracy of a simplified physical reflector model which offers a significant calculation time advantage is also investigated over a wide range of parameters, and it is shown to perform well even for relatively small systems.