Measuring 5G Electric Fields Strength With Software Defined Radios

The effect of electromagnetic radiation on public health is a recurring topic in the societal and political discourse, peaking with the introduction of every new generation of cellular technology. With the introduction of 5G, promising high peak download speeds as well as high-power beams, there is a need to revisit traditional measurement approaches. ICNIRP, a.k.a the International Committee on Non-Ionising Radiation Protection, offers a useful guideline to evaluate the electromagnetic field exposure of living tissues and provides some limits to keep exposure well below the threshold where it is considered harmful. However, modern packet radio technologies such as 5G or Wi-Fi are different from old broadcasting technologies. They deliver high power in very short bursts, spread over a wide band, thus increasing the difficulty of measuring electric fields with traditional instruments, such as spectrum analyzers. In addition, 5G promises a high spatial focusing performance, which means that the field can vary significantly even in a small area. Hence, measurements with a higher spatial density than we can achieve with expensive and bulky spectrum analyzers are urgently needed. Software-defined radios (SDRs), as a size- and cost-efficient alternative, can be used to capture signals in the time domain and thus increase measurement accuracy. However, software-defined radios are not designed to be used as RF power meters. They require accurate calibration and data analysis to ensure the measured power is correct. The aim of this work is to provide a general framework to calibrate SDRs, enabling them to measure RF power and extract the corresponding electric field value. Subsequently, the influence of the SDR parameters on the accuracy of the electric field measurement is investigated. To assess the performance of the proposed calibration framework in a real-life scenario, we rely on our private 5G network with a calibrated SDR to measure the RF power from a 5G network. Our measurements show that the average electric field exposure of 5G networks is well below 1 V/m.