Search and rescue antenna for Galileo constellation

We present in this paper the design of the Search and Rescue (S&R) antenna planned to be mounted on GALILEO constellation. The antenna assembly operates in dual band (UHF for receive and L-Band for transmit). Two electrically independent antennas are disposed sharing a common envelope. The challenge of the design was to minimize the interaction between antennas while reaching a high gain efficiency respect to the foot print area. The specified coverage is earth global for low orbit satellite. Peak gains higher than 13dBic were achieved. The selected configuration is an array of six resonant quadrifilar helices for UHF mission with an L-band antenna located in the centre. The L-band antenna is made of cross dipoles enclosed between a flat ground plane and a subreflector disk (SBF). As the operational frequencies are narrowband and polarization is circular, all antenna elements are self- phased in order reduce the complexity of the array feeding.