The primary purpose of the RF system on board a satellite is to allow data communications with the ground. There are a number of factors that influence the design. A brief description of current systems and considerations will be given. Licensing is another important factor. The spectrum is getting crowded, so there is an inherent push to moving up in frequency where there is generally more bandwidth and fewer users. In addition to all this there are relevant standards to which it would be wise to comply with, for example CCSDS (Consultative Committee for Space Data Systems). A very brief introduction to CCSDS will be provided, in as much as it applies to SSTL. Beyond this, the future requirements for data rate are going up all the time, while the DC power on the satellite available for doing this remains largely the same or less. This imposes technical challenges, forcing the use of new modulation methods and coding. All of these factors must be combined into forming a strategy for RF development at SSC, and a brief summary of current and planned work will be given.