On-axial defocused characteristic analysis for Cassegrain antenna in optical communication

In order to reduce the chromatic aberration problem of the multiple wavelength, reflex cassegrain antenna is widely used in space optical communication system. There are many external factors such as temperature and vibration that may cause defocusing in practice which has influence on Cassegrain antenna. That is to say, the primary mirror's and the secondary mirror's focus cannot be coincided, so it will bring impact greatly on transmission efficiency. This paper studies the effects on the transmission characteristics of the defocused Cassegrain antenna system. While defocused 2.5 cm, the transmission efficiency of Cassegrain antenna will decrease 80% of the initial efficiency. So it is very important to maintain optimum position for high transmission efficiency.