Calibration of antennae on 3m OATS

Radiated emission measurement of commercial products is usually performed on the open area test site (OATS). Test instrumentation and antennae are used to obtain the radiated emission data. The measurement error accumulated by each instruments, sensors and OATS used in the measurement may creates doubts on the validity of the observed data. One of the most common sources of error in radiated emission is antenna. Using an inaccurately calibrated antenna can result in mistaken rejection of valid test data. It can also lead to mistaken acceptance of invalid test data which is still the worst. The calibration of EMC antennae are usually performed by two methods as outlined in ANSI C63.5-1998 specification i.e. standard site method and reference antennae method. Most of commercial labs used 3 m OATS to perform the emission measurement. In view of this, a study has been carried out to find out the most suitable and acceptable methods to calibrate the antennae on same.