There are many types for earth station antenna, which are : 1. Prime Focus Feed Most popular due to its excellent efficiency (approximately around 62%) Because of its relatively large surface, the prime focus antenna is less sensitive to small directional deviations and there is a better chance of receiving signals outside the normal footprint. Usually limited up to 4.5 mtr diameter Sometimes problem with OMT adjustment for "prima" Cross-Polar Isolation (CPI) characteristics Because of the LNB is mounted centrally, a lot of the incoming signals are blocked by the LNB on the way to the antenna surface. 2. Offset Feed Better efficiency due to reduction of Feed (and spars) "blocking" Simple to deploy, usually to Fly-away or Transportable SatCom terminals Much easier to adjust in achieving very accaptable Cross-Pol Isolation (CPI) Due to its simple construction, while satisfying the requaired ruggedness of Feed support, normally these are produced max
My writing on satcom and vsat, slightly of networking, and small portion of my hobby