ABSTRACT
Amplitude modulated (AM) radio stations are required to manage the spectrum occupied by their AM broadcast signals. The Federal Communications Commission requires at a minimum that AM stations perform annual equipment performance measurements (EPMs) of their spectral occupancy. AM, Frequency modulation and television stations must conduct EPMs when new transmission or stereo generation equipment are installed or other modifications of the transmission system are made. In the transmission plant and the AM antenna system, faulty components, connections and bonding can introduce arc noise, impedance mismatches, intermodulation and reradiation that affect the radiated signal. A commercial off-the-shelf AM antenna is typically not calibrated. Field intensity meters are equipped with and calibrated to antennas that cover the lower harmonics of the AM band. The antenna factor establishes the relationship between the received signal strength indicated on the analyzer display and the actual field strength of the signals under test.
