The Model 3115-PB is a specialized version of the Model 3115 Double-Ridged Waveguide Horn Antenna, equipped with a pre-amplifier package and calibrated as a single unit. This calibration accounts for any mismatches between the antenna and pre-amplifier, which is reflected in the provided antenna factor (AF). Please note that the 3115-PB is not intended for radiated spurious emission (RSE) testing of intentional radiators.