An active electro-optical loop and dipole probe for electromagnetic near-field measurements

An active electro-optical dipole and loop probe have been developed to measure electromagnetic near-fields. For the assembly of the probes attention has been paid to the sensitivity of the probe, to the susceptibility of the probes to interfering electromagnetic fields and to their high-frequency behaviour. The electro-optical loop probe (1 cm/spl times/1 cm) has a sensitivity comparable to that of conventional loop probes of the same size, can measure magnetic fields up to 0.1 mA/m and has a linear dynamic behaviour of at least 60 dB. The electro-optical dipole probe (h/sub eff/=1 cm) has a sensitivity that is better than that of conventional dipole probes of comparable size, can measure electric fields up to 30 mV/m and has a linear dynamic behaviour of at least 60 dB. In contradiction to most of the reported near-field probes with an optical link there is no conversion of the antenna signal to a DC-signal which means that all the spectral information of the electromagnetic field is preserved. This makes these probes excellent instruments for diagnostic EMC-measurements.