Measuring G/T with a Spherical Near-Field Antenna Measurement System via the CW-Ambient Technique

In this paper, we demonstrate a method to compute Gain over Noise Temperature (G/T) for active Units Under Test (UUTs) measured with a spherical near-field (SNF) antenna measurement system. A brief review of spherical near-field theory is presented, followed by the derivation of the equation required to compute G/T using the Continuous Wave-Ambient, or CW-Ambient technique. This result is applied to data measured with a spherical near-field measurement system. By using a separable UUT, we are able to demonstrate the validity of the CW-Ambient technique for a SNF measurement system.