Continuous Electromagnetic Emission Measurement Setup with Antenna Position Tracking

Abstract

ZAbstract -For measuring the maximum electromagnetic emissions around equipment many test methods use the frequency domain, traditionally using a super-heterodyne test receiver. However, for large equipment under test the frequency domain method is very time consuming when the measurements are performed at low frequencies, below 150 kHz, where small bandwidth and thus long measurement time is needed. Timedomain measurements are now replacing the traditional superheterodyne receivers, but the commercial time-domain receivers still use a first mixer stage. However, at low frequencies, low cost digitisers can do the same job directly in the baseband. Using fast signal processing, this method allows to continuously measure the radiated magnetic field around the equipment under test. Combined with position tracking, this allows to identify areas of maximum emissions very fast. These positions are then used to obtain a more detailed spectral analysis of emissions by increasing the measurement time over those spots. In result, the whole measurement procedure can be significantly optimized by spending less time over areas of lower interest, and putting more focus on areas of potentially high emission levels. This paper presents the concept as well as an experimental comparison of three antenna movement approaches satisfying the NRE01 and RE101 radiated emissions measurement procedures.

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

“…Although not expected in the low-frequency range, if the EUT radiates strongly at a certain angle between the marked positions, the highest emission level can be underestimated [7]. Using a multiaxial antenna with multichannel digitizer, the entire measurement time can be decreased to a couple of minutes [8]. With the decreased measurement time, more antenna positions can be used around the EUT.…”

“…In [7] the prospect to use a digitizer for TD measurements is discussed. In [8] the evaluation of non-stable emission is shown. Another advantage of these digitizers is the multiple inputs, typically two or four, sometimes even eight [9], as opposed to the EMI receivers that typically have only one.…”

On-site Radiated Emissions Result Visualization using Augmented Reality

“…For that purpose, the localization of the high EMI areas should be done. The attempt to create an EM emission map was shown in [3]. However, the usability of such a method is limited due to the position of the camera and the antenna tracking technique working only with flat surfaces.…”

“…This paper extends this study by implementing augmented reality (AR) glasses for the purpose of both tracking the antenna and displaying the results. The advantage is based on continuous visual feedback about the measured data being continuously plotted in an AR environment to help the test engineer find the highest emission spots and adapt accordingly, as described in [3]. In the end, the time to evaluate the EM environment around large equipment and complex systems decrease drastically.…”

Efficient Time-Domain Multi-Channel Measurements using a Multi-Axis Antenna for Frequency Range below 30 MHz

“…In [5] the prospect to use a digitizer for TD measurements is discussed. In [6] the evaluation of timevariant emission, and the advantages for EMI measurements, is shown. Another advantage of these digitizers is the multiple inputs, typically two or four, sometimes even eight [7], as opposed to the EMI receivers that typically have only one.…”