  We study the electromagnetic coupling of the array of Gaussian and
multi-moded horn antennas to the dual-reflector submillimeter-wave telescope on
the ESA PLANCK Surveyor designed for measuring the temperature anisotropies and
polarization characteristics of the cosmic microwave background. In this paper,
we present the results of our analysis concerning the measurement of
polarization with tilted off-axis dual-reflector Gregorian telescope and the
propagation of multi-moded beams through such a system.
