Ku- vs. C-band and digital vs. analogue television transmission in a tropical climate

This paper analyses the K_u-band versus C-band transmission for digital and/or analogue TV, keeping in mind K_u-band attenuation in the tropical climate as a function of earth-station antenna elevation angle. The analysis is done for the case that adjacent satellites illuminate the same converage area and that interfering signals are of same e.i.r.p. and spectral make-up. It is shown that a multiplex of compressed digital carriers requires smaller receiving antennas than a single analogue TV carrier. It turns out that because of low power requirements of the compressed digital carrier and/or for high e.i.r.p. values, the earth-station antenna diameter is interference limited. Below the interference limit the aperture can only be reduced by applying an elliptical area to provide for a narrower beamwidth along the geostationary arc.