Employing electromagnetic fields (EMFs) in new wireless communication and sensing technologies has substantially increased the level of human exposure to EMF waves. This paper presents a useful insight into the interaction of electromagnetic fields with biological media that is defined by the heat generation due to induced currents and dielectric loss. The specific absorption rate (SAR) defines the heating amount in a biological medium that is irradiated by an electromagnetic field value. The paper reviews the radio frequency hazards due to the SAR based on various safety standards and organisations, including a detailed investigation of previously published work in terms of modelling and measurements. It also summarises the most common techniques utilised between 1978 and 2021, in terms of the operational frequency spectrum, bandwidth, and SAR values.
larger than the bandwidth of the PDs. The fundamental frequencies used were 10 GHz and 10.1 GHz, and the result of the measurement of the UTC-PD at 40 mA is shown in Figure 3 (right inset). The two tone measurements were repeated for different photocurrents, and the results are presented as the OIP3 versus the photocurrent in Figure 4(a). The OIP3 of the UTC-PD was found to be increasing with bias voltage, and therefore a bias À6 V was chosen, which was found to be the largest safe voltage. The increase of the OIP3 with voltage is consistent with results of [8]. Because of the dynamic range limitations of the ESA, the measurements of PIN-PD and the UTC-PD were limited to photocurrents between 5 and 13 mA, and 15 and 40 mA, respectively. The UTC-PD had about 15-20 dB larger OIP3 in this measurement range. The measurements of the linearity and noise can be added together under the assumption that the photodetector is limiting the link, as mentioned in the introduction, and thus, the SFDR can be calculated and is plotted as a function of photocurrent in Figure 4(b). As a consequence of the high OIP3 of the UTC-PD, the SFDR is more than 10 dB higher than for the PIN-PD.
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