Dual-constellation operation on GPS and Galileo is now standard practice rather than a hedge, and this antenna is built for the 1559 to 1591 MHz overlap where both signals sit. The 70 dBc rejection at 1650 MHz is the distinguishing specification, and it matters on any spacecraft carrying an L-band or S-band transmitter in close proximity to the navigation receiver. Passive gain is 5 dBic typical with 2 to 3 dB axial ratio, LNA gain is 12 to 18 dB and customisable on request, and output 1 dB compression is 12 to 15 dBm. Supply is 4.5 to 12 VDC at 25 to 35 mA through an SMA female interface, in a 97 x 97 x 24 mm (3.8 x 3.8 x 0.95 in) envelope at 130 g. Built for the harsh conditions of space, the sealed and vented housing addresses corona, multipaction, atomic oxygen and MMOD across a five-year LEO mission life. Qualification is to NASA GEVS (GSFC-STD-7000) with 14.1 GRMS random vibration and humidity per MIL-STD-810 Method 507.6, across -70 to +100 °C, with 500 krad(Si) radiation tolerance and no destructive single event effects to 37 MeV-cm²/mg. ATH-L-003-RH is the matching test hat, and LNA-L-002 provides the amplifier alone for hardware-in-the-loop and irradiation testing.