Wideband Receive Antennas of Sensor Stations for GPS/Galileo Satellite

This paper describes wideband L-band receive antennas of sensors for GPS as well as Galileo satellites. The antenna should provide small variations of the phase center and small group delay variations. In order to meet the specification on antenna gain, conical spiral antenna is considered. A conical spiral is arranged in a circular cylindrical cavity. The spiral is composed of bifilar coaxial line. These coaxial lines are matched to 50 Omega coaxial cable by using 1:4 RF transformer and balun. The antenna gain at zenith is greater than 6 dB and the minimum gain at low elevation angle is about -3 dB over lower frequency bands (El and E6 bands) but that is -3.5 dB over high frequency band (LI). The phase center variation of the antenna is less than 4.3 mm over whole operating frequency bands. The antenna has good performance characteristics.