Radiation pattern of a PCB based probe intended for near field measurements

In some situations, the OATS (open air test site) far field condition cannot be satisfied, and near field measurements must be performed. The EMI environment inside a car is one of these situations, where only near field probes can be used for measurement. We developed a near field probe that can measure the electric and magnetic fields simultaneously. The probe was built on a PCB (printed circuit board) along with the electronics needed to transmit the signals through an analog optical link. Calibration of the probe was performed in a TEM cell. The results for the sensitivity as a function of the frequency and the radiation pattern are presented.