MIL-STD Double Ridge Horn Antenna 800 Watts CW The AH-220 is a broadband, linearly polarized Double Ridge Waveguide Horn Antenna, operating over the frequency range of 200 MHz to 2 GHz. While it is designed to serve as the receiving antenna for radiated emissions tests between 200 MHz and 1 GHz, as specified within RE102 of MIL-STD-461, it can also be used as a transmitting antenna for radiated immunity tests.