A typical reflector antenna consists of a feed horn and a rotating parabolic .The feed is placed in the focus of the metal reflector, it focuses high frequency energy and receive device through the waveguide tube. The characteristic of this antenna is that can be made into any size according to the requirements of frequency range. Generally speaking, the quality of the reflector and the accuracy of the equal field’s strength can affect the gain and efficiency of the antenna. Especially, the accuracy of the equal fields strength is not allowed for any deviation, otherwise it will cause the focus to move. As to the receiving antenna, regarding deviation of focus, it means that the high frequency energy reflected by the main reflector can be not reached the feed system completely. After the loss of high frequency energy, it makes efficiency and gain of antenna become worse. When the diameter of reflector antenna is 4.5m, the gain of antenna can reach 44dB-47.3dB. Regarding our earth antenna ,it is from 2.4m to 6,2m, which is ring focus satellite reflector antenna structure.