Antenna Factor Calculator and Conversion

This page covers the antenna factor definition and provides an antenna factor calculator. It also explains the conversion between antenna factor and gain, including the relevant formulas and equations.

What is Antenna Factor?

In EMC testing, an antenna is connected to an RF receiver like a spectrum analyzer, network analyzer, or RF voltmeter to measure field strength (E). These devices use a load impedance (Z_L) that matches the antenna impedance.

The antenna factor can be expressed as follows:

Where:

• E_i represents the incident field strength.
• V_rec represents the received voltage.
• “h” represents the antenna’s effective height.

Antenna factor (AF) is expressed in units of dB/meter or meter^-1.

Antenna Factor to Gain Conversion Calculator - 1

The following calculator performs antenna factor to gain conversion.

Example #1:

• INPUTS: Antenna factor = 2, Frequency = 2400 MHz
• OUTPUT: Gain (dBi) = 35.86

Gain to Antenna Factor Conversion Calculator - 2

The following calculator performs gain to antenna factor conversion.

Example #2:

• INPUTS: Gain (dBi) = 35.8, Frequency = 2400 MHz
• OUTPUT: Antenna factor = 2.06

Antenna Factor Calculator Equations or Formula

The equations or formulas above are used for antenna factor to gain conversion and vice versa. This formula is taken from the paper “Antenna Factor Calculations and Deviations” by A.H. Systems, Inc.