Shared-aperture dual-port operation saves panel area, and the specification that makes it viable is port isolation: -35 dB TX to RX excluding the LNA and -20 dB including it, with 10 dB of multipaction margin verified at the full 20 W transmit rating. The receive path carries an integrated filter and LNA at 14 to 18 dB gain and 1 to 3 dB noise figure, with 60 dBc rejection at 2200 MHz protecting it from the collocated transmit port. Transmit passive gain is 3 to 4 dBic and receive 2 to 4 dBic, both at 85 to 100 degree half-power beamwidth with axial ratio between 1 and 4 dB depending on port. Supply is 4.5 to 12 VDC at 25 to 35 mA in a 97 x 97 x 30 mm (3.8 x 3.8 x 1.19 in) envelope at 290 g, under 1U, with SMA female interfaces. Built for the harsh conditions of space, the sealed and vented housing addresses corona, multipaction, atomic oxygen and MMOD over 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) tolerance. ATH-S-003-RH is the matching dual-port test hat.