## 3 Results and Discussion
### Multi-Location On-Body RF EMF Exposure Evaluation (Virtual Measurements)  
In articles presenting research using several PEMs [15; 16; 17; 20] it was already suggested that limiting the dispersion of RF EMF on-body measurement results can be achieved by conducting wearable measurements simultaneously at several on-body locations. As mentioned earlier, in realistic measurement conditions, RF EMF sensitive equipment are usually placed on the torso, avoiding the head and arms, the movement of which may affect the operation of the devices [15]. Figure 8 (regarding narrowband multichannel measurements case) presents the KX1 bp ratio (means and MMR values) derived following the formula:  
\[\text{KX1}=\text{E}_{\text{x1}}/\text{E}_{\text{up}}, \tag{3}\]  
where: \(\text{E}_{\text{x1}}\)--E-field value measured by an on-body multi-location equipment in considered combination of locations: H, or H and combination of C, W and A; \(\text{E}_{\text{up}}\)--the unperturbed E-field value set in the simulations (\(\text{E}_{\text{up}}=10\) V/m). Figure 7: The KX-RMSbp ratio, presenting the discrepancy between the unperturbed E-field and the results of E-field measurements by broadband wearable equipment in various locations near the human body (analyzed subsets of results over all directions of RF EMF propagation and E-field vector polarizations, when the measurement equipment is located on: H—head, C—chest, A—arm, W—waist, F—front, B—back, R—right side, L—left side); the distribution of the broadband RMS values at a particular locations are characterized by MMR—the range from minimum to maximum values (bar), and mean value (dot). When using multi-location measuring equipment, the KX1 bp ratio distribution may be evaluated from results of measurements obtained at various locations of the measurement ball-probes and averaged over any of two to seven considered locations of multi-point measurements: over the head (H), on the chest (C), waist (W) and arms (A). Figure 9 summarized KX1 bp ratio evaluated for considered PEM locations when broadband measurements are performed using ball-probe (KX1-RMSbp). Figure 8: The results of multi-location ball-probe measurements (multi-channel narrowband analysis) evaluating the E-field exposure, normalized to the parameters of an unperturbed (homogeneous) E-field—the KX1 bp ratio—in the location of the human body under exposure evaluation, averaged over all the considered exposure scenarios (two to seven ball-probes): measurement points located over the head (H), on the front or back of the chest or waist (CB, CF, WF, WB), and on the left or right arm (AL, AR); the distribution of results of KX1 bp ratio is characterized by MMR—the range from minimum to maximum values (bar), and mean value (dot). Figure 9: The results of multi-location measurements (broadband analysis) evaluating the E-field exposure, normalized to the parameters of an unperturbed (homogeneous) E-field—the KX1-RMSbp ratio—in the location of the human body under exposure evaluation, averaged for all the considered exposure scenarios: two to seven ball-probe measurement points located over the head (H), on the back or front of the chest or waist (CB, CF, WF, WB and on the left or right arm (AL, AR); the distribution of the broadband RMS values KX1-RMSbp are characterized by MMR—the range from minimum to maximum values (bar), and mean value (dot). Tables 4-6 compared the dispersion of results for single and multi-point measurement locations expressed by above mentioned KX1 bp ratio across the considered RF EMF frequencies for \(\phi\)50 mm E-field ball-probe, and KX1 ss ratio in case of point E-field small-sensors located at various distances to body. The largest differences, regardless of the number of measurement points covered by simultaneous measurements, were obtained for a frequency of 100 MHz (when the wavelength of EMF, approximately three meters there, is nearest to the human body height).