How 5G NR Signals Impact on the Response of Broadband Electric Field Probes

Abstract

Overview

New-generation mobile communication systems, particularly long term evolution (LTE) and 5G new radio (NR), employ digitally modulated signals. These signals have significant peak-to-average power ratios that may interfere with the normal operation of diode-based wideband electric field probes, potentially causing an overestimation of field strength.

Methodology & Findings

The study uses a novel methodology to analyze how broadband electric field probes respond to 5G NR signals compared to standard continuous wave (CW) radiation. By using test models designed by the 3rd generation partnership project (3GPP), the study experimentally assessed the impact of factors such as signal center frequency, modulation complexity, time/frequency duplex configuration, signal bandwidth, and orthogonal frequency-division multiplexing (OFDM) subcarrier spacing.

• Overestimation of field strength can be as high as several tens of percent.
• The overestimation is more pronounced in scenarios involving full-frame and larger bandwidth signals.
• Suggests extension of calibration standards to accommodate the distinct behavior of probes under 5G and CW signals.

Conclusion

Considering the high crest factor of 5G signals, electric field probes tend to overestimate the amplitude when exposed to intense fields. A key mechanism behind this is the diode’s response to peak strength rather than the rms value. A proposed solution is incorporating a variable attenuator at the diode's input to ensure the diode operates within the optimal range.

Furthermore, caution is advised when using diode-based sensor probes for measuring electromagnetic fields expected to exceed 6 V/m to prevent non-compliant readings concerning exposure limits.