Radio Transmitter Output Power

Value to Enter:

Enter the transmitter power that will be used for the radio. The value is the power output of the transmitting radio (which is the input power supplied to the antenna distribution system), and not the aggregate output power after considering antenna gain (often called the EIRP, "Effective Isotropic Radiated Power".) A typical Wi-Fi client device (notebook computer, hand-held inventory scanner, PDA, or tablet PC) often has an input power of 30mW. Some high-power mesh routers boast power specifications of 23 dBm (200 mW). For many years a typical 802.11 access point operated at 100 mW (20 dBm).

Significance of This Value:

When the two radios are specified with different input power levels, the calculator uses the smaller value for calculations. The single most arbitrarily limiting factor in a wireless network link is the power level of the weakest transmitter. The lowest power level defines performance for both sides of the link. The power level is used by the calculator as part of the link suitability assessment. Power level and antenna gain are attenuated by cable loss, rain fade, link fade, and free space path loss.

Background and Technical Perspective:

Additional information is available in our Wi-Fi: Just the Facts tutorials. Refer to the Antenna section and to the High Power Access Point discussions.