The basics of the EMC profession often get buried under the day-to-day effort of continuous measurement and volume of test and reporting paperwork. The fundamental parameter of the most common technical tool, the EMC antenna, is used over and over without thought as to its actual meaning. This parameter is the antenna factor (AF). A review of the basics behind this parameter, the transmit antenna factor (TAF), provides a basic for the use of numerical values, and a more fundamental understanding of radiated EMC measurements.