An S band antenna system used for communication on Earth observation microsatellite

Many types of antenna have been used for spacecraft applications in low Earth orbit. Many designers have concentrated on the use of simple and mechanically stable devices such as monopole arrays constructed from steel tape. As the requirement for payload communication increases however, the requirement for more optimal antennas is highlighted. The spacecraft built at Surrey (UK) carry a variety of payloads ranging from Earth imaging camera systems through email like communication systems to small-scale space science instruments. A common factor in these missions however, is the necessity to return data to the ground either for telemetry to determine the state of health of the spacecraft or as the product of the payload systems for processing and examination. This return of data is supported by the radio frequency link between spacecraft and ground station. The antenna may be able to be optimised to minimise effects on the link of such characteristics as changing range. In this paper we describe an S band antenna system used on microsatellite constituted by three different RF antennas: S-band patch antenna (for command uplink), S-band monopole antenna (for telemetry downlink), and S-band quadrafilar helix antenna (for payload downlink).