GROUND ANTENNAS IN NASA DEEP SPACE TELECOMMUNICATIONS

Ground antennas are the major visible components of NASA's Deep Space Network (DSN). The role, key characteristics, and performance of these antennas in deep-space telecommunications are described. The system a nalyses and tradeoffs to optimize the overall ground-to-spacecraft lin k and to define future missions are elaborated from an antenna perspec tive. Overall performance of receiving systems is compared using the w idely accepted G/T figure-of-merit, i.e., net antenna gain divided by the operating system noise temperature. Performance of past, present, and future antennas and receiving systems is discussed, including the planned development of a worldwide network of 34-m-diameter beam-waveg uide antennas. The need for multifrequency operation, presently at S- and X-bands, and in the future at Ka-band, is discussed. The resulting requirements placed on antenna technology are highlighted. Beam-waveg uide antenna performance to further improve performance and operationa l advantages is discussed.