Low back radiation compact antenna for data downlink in LEO satellites

We describe the design, manufacturing and measurement of an antenna with an hemispherical type radiation pattern used in the space segment X-band data downlink subsystem. In particular, this antenna corresponds to the flight model of mission SAC-D/AQUARIUS, which is a LEO earth observation satellite. The chosen solution is a compact choke ring type antenna, which reduces back radiation. By using a septum polarizer, selectable polarization, high power handling, and high structural stiffness are achieved.