Dyadic analysis of partially coherent submillimeter-wave antenna systems

We describe a procedure for simulating the behavior of partially coherent s ubmillimeter-wave antenna systems. The procedure is based on the principle that the second-order statistical properties of any partially coherent vect or field can be decomposed into a sum of fully coherent, but completely unc orrelated, natural modes. Any of the standard electromagnetic analysis tech niques-physical optics, geometrical theory of diffraction, etc-can be used to propagate and scatter the modes individually, and the statistical proper ties of the total transformed field reconstructed at the output surface by means of superposition. In the case of modal optics-plane waves, Gaussian o ptics, waveguide mode matching, etc.-the properties of the field can be tra ced directly by means of scattering matrices. The overall procedure is of c onsiderable value for calculating the behavior of astronomical instruments comprising planar and waveguide multimode bolometers, submillimeter-wave op tical components, and large reflecting antennas.