The changes in the E_{max} and the E_{avg}, which were measured at 46 different locations, are given in Figure 3a and Figure 3b respectively. As seen from Figure 3a, the maximum E_{max} acquired is 3.72 V/m at location 26 for the second measurement (M2), while maximum E_{avg} acquired is 2.67 V/m at location 26 for the third measurement (M3). The reason for the high E values observed at this point may be due to the fact that the location has a high user density and is close to one of the base stations. The statistical characteristics of measured values are specified and listed in .

Figure 3 a) Maximum (E_{max}) b) Average (E_{avg}) Es versus locations

Table 2 Statistical characteristics of the measured values

Band selective measurements were fulfilled at all locations using the Narda SRM 3006 to specify the effect of E sources into the total E. All band selective measurements are shown in Figure 3. An example of the details of the SRM–3006 measurements, which involve the E sources (frequency ranges, service name etc.), caused pollution as shown in for location 26. In the table, each E source has a specific index number and the 23^{rd} index is the representation of E levels inclusive of undefined frequency bands, and the 24^{th} index is the representation of total E (E_{T} values of the medium.

Figure 4 Band selective E values

Table 3 Frequency selective E values

It is seen from that the primary sources of E are LTE900, LTE800, GSM1800, GSM900, LTE1800, and UMTS2100 bands. When total E is 3.616 V/m, 2.243 V/m of this value is produced by UMTS2100, while 2.048 V/m, 1.402 V/m, and 0.913 V/m are produced by GSM900, LTE800, and LTE900 respectively. The total E of medium is computed as follows:

$$\begin{array}{}{\displaystyle {E}_{T}=\sqrt{\sum _{i=1}^{23}({E}_{i}{)}^{2}}}\end{array}$$(1)

where *E*_{i} is the electric field for *i*^{th} band. The other transmitters excluding 18 bands give rise to *E*_{23}. The contribution percentage (*P*_{i}) of each band is computed as in Eq. 2.

$$\begin{array}{}{\displaystyle {P}_{i}=\frac{{E}_{i}^{2}}{{E}_{T}^{2}}\times 100}\end{array}$$(2)

The pie chart illustrating the divisions of all E sources is given in Figure 5 for location 26. As seen from Figure 5, 88.7% of total E in the medium is emitted by base stations which use LTE800, LTE900, GSM900, LTE1800, UMTS2100, and the other frequency bands. Among these systems, UMTS2100 has the most contribution with 43.6%.

Long term E measurements were taken to determine the change of E values measured at location 26 during a day, and the results are given in Figure 6. Figure 7 shows the measurement location 26. Measurements started at 6pm and continued until the next day. Figure 6 shows a great variation depending on the measurement hours. It is seen that the number of users actively using the base station is the main factor influencing the E. Low E values were measured between the hours of 05:00–07:00 in the morning (mean E is 7.05 V/m), and very high E values between 12:00 and 18:00 hours (mean E is 10.5 V/m). The highest measured E value was 17.53 V/m while the 24 hour average was 9.45 V/m. The standard deviation value is 2.02 V/m for this 24 hour measurement.

Figure 6 E levels measured for 24 hour at location 26

Figure 7 A picture of location 26

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