EMC/EMI near-field testbed for EM phasor measurements using active optical sensors

An automated near-field testbed for system- to chip-level EMC/EMI evaluations in the RF domain capable of precise EM phasor measurements is presented. The scanning system combines a large scanning volume with micrometre resolution. An optical surface reconstruction system allows measurement of the surface structure of the device under test (DUT) with better than 20μm uncertainty, allowing scans at a precisely known separation above arbitrary electronic components. Miniaturized active electro-optical time-domain ultra-wideband E- and H-field sensors for the frequency range from 0.01 to 6 GHz combined with a high speed vector signal analyser are applied to measure the EM phasor field distribution with a dynamic range of >120dB. The isolation of the probes eliminates perturbation of the EM field of the DUT compared to electrically connected probes and offers up to 60dB better sensitivity than passive electro-optical probes.