Efficient Multichannel Time-Domain Multiaxis Loop Antenna Measurement for Frequencies below 30 MHz

Conventional frequency-domain measurements are slow and are not able to grab time-varying effects, compared to time-domain measurements. Standard measurement procedures, for example CISPR 36 for electric vehicles, requires measurements at multiple positions around the equipment under test. Small resolution bandwidth in combination with long dwell time for every frequency step, results in a long measurement time. This is especially true in the lower frequency range as the bandwidths are small and thus need more measurement time. CISPR 36 requires also using only one antenna in parallel or perpendicular position to the equipment under test at once. Using time-domain measurements, the measurement speed can be already significantly improved. The effectiveness of measurements can be increased drastically if multiple antennas are positioned at several locations around the equipment under test, and multiple digitiser channels are used in parallel. A new antenna construction for multidirectional measurements in combination with a cost-efficient multichannel digitizer for time-domain measurements in the frequency range below 30 MHz is proposed in this paper. Simulation results, theoretical background and initial measurements are shown, proving that such a method is indeed viable.