Identical to CI 271 except its electrical performance is specified over the frequency range of 403-512 MHz in various band segments with VSWR limits shown. Stub antenna designed to withstand the harsh environments associated with the underside of an aircraft. Antenna radiator is mechaniclly captivated and is sealed against leakage. All exposed metal surfaces are nickel-plated for corrosion resistance and long service. CI 273 mounts through a single 0.60” hole. BNC connector is standard.