Assessment of short/long term electric field strength measurements for a pilot district

Cetin Kurnaz; Dogan Yildiz; Serap Karagol

doi:10.1515/phys-2018-0013

Article Open Access

Assessment of short/long term electric field strength measurements for a pilot district

Cetin Kurnaz , Dogan Yildiz and Serap Karagol

Published/Copyright: March 20, 2018

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From the journal Open Physics Volume 16 Issue 1

Abstract

The level of electromagnetic radiation (EMR) exposure increases day by day as natural consequences of technological developments. In recent years, the increasing use of cellular systems has made it necessary to measure and evaluate EMR originating from base stations. In this study, broadband and band selective electric field strength (E) measurements were taken at four different times in order to evaluate the change of short term E in Atakum district of Samsun, Turkey. The measurements were collected from 46 different locations using a SRM 3006 and a PMM 8053 EMR meter in a band from 100 kHz to 3 GHz, and the maximum E (E_max) and the average E (E_avg) were recorded. The highest values have been noticed in these measurements at 9.45 V/m and 17.53 V/m for E_avg and E_max respectively. Apart from these measurements, 24 hour long term E measurements were taken at a location where the highest value was observed and analyzed, to observe the change of Es during a day. At the end of the study, a tentative mathematical model that helps in computing the total E of the medium with 95% accuracy, was obtained.

Keywords: Electric field strength; electromagnetic (EM) radiation; EM measurement; base station; statistical analysis

PACS: 84.40.Ua; 84.40.Ba; 87.50.S-; 87.50.cm

Introduction

With the rapidly evolving technology, the use of wireless communication systems increases day by day. Devices using wireless systems use electromagnetic waves for communication, and these systems conduce toward an increase in the use of electromagnetic radiation (EMR). Cellular systems occupy a large part of our daily lives in wireless systems and cellular systems users communicate with each other with the help of base stations. Users demanding communications from anywhere, increase of multimedia usage, and the ability of base stations to operate a limited number of users at the same time, force operators to install more base stations. Established base stations are actively broadcasting EMR for 24 hours a day so that people living in these areas are exposed to EMR radiation of the base stations even if they do not want to be. Each base station behaves like an EMR source, and this increase in base stations causes the level of EMR that is exposed to increase daily.

There are a number of limitations and standards that have resulted from some research by certain international organizations that are examining the effects of EMR on human health. These limitations are specified by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [1], which is based on the assumption of 24 hour exposure recognized by the World Health Organization (WHO). In Turkey, restrictions and regulations related to exposure to EM fields are established by the Information and Communication Technologies Authority of Turkey (ICTA) [2]. In Turkey, 75% of ICNIRP’s restriction values are applied by ICTA. The electric field limit values determined by ICTA and ICNIRP are shown in Table 1. The values in this table are the average values given after EMR exposure for six minutes. There are 3 communication operators in Turkey currently used by the users and they use 2G (second generation), 3G (third generation) and 4G (fourth generation) systems. According to [2], the electric field strength (E) limits are 30.9 (V/m) for 900 MHz base station, 43.7 (V/m) for 1800 MHz base station, 45.75 (V/m) for 3G systems, which is 2100 MHz, and also 45.75 (V/m) for 2600 MHz base station.

Table 1

Reference EMR levels of ICNIRP and ICTA

Frequency range (MHz)	E (V/m)
	ICNIRP	ICTA
0.010 – 0.15	87	65.25
0.15 - 1	87	65.25
1 - 10	87/f^1/2	65.25/f^1/2
10 - 400	28	21
400 - 2000	1.375f^1/2	1.03f^1/2
2000 - 60000	61	45.75

f is frequency in MHz

Obtaining EMR values in crowded settlements, especially where there are too many cellular systems, is very important to be able to examine the effects of EMR on human health. For this reason, a number of studies have been conducted in the literature [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13] to measure EMR contamination from base stations and to investigate the effects of these measurements on human health. Therefore, in this study, E measurements were taken at four different times in order to examine and evaluate the change of E in Atakum district which is one of the most crowded districts of Samsun, Turkey.

1 Electrical field strength measurements

In this study, the E measurements were conducted using a SRM-3006 and a PMM 8053 EMR meter in Atakum district at 46 different locations considering the number of users, distance from base stations and line of sight. In the measurements, the maximum E (E_max) and the average E (E_avg) were recorded. The total E in the band between 100 kHz – 3 GHz is measured using the PMM–8053 with the EP-330 isotropic electric field probe [14] twice in August 2015 named as M1, M2, and in December 2016, named as M3, and M4 respectively, while band selective measurements are conducted using the Narda SRM–3006 with the 3501/03 isotropic E-field probe [15] in February 2017. The E measurement locations are shown in Figure 1, and visuals of the measurements using the PMM-8053 and SRM-3006 are shown in Figure 2.

Figure 1

Measurement locations in Atakum district

Figure 2

Taking measurement with a-) PMM 8053, b-) SRM 3006 EMR meter

2 Measurement results

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 Table 2.

Figure 3

a) Maximum (E_max) b) Average (E_avg) Es versus locations

Table 2

Statistical characteristics of the measured values

	E_max (V/m)			E_avg (V/m)

	Max.	Mean	Std.	Max.	Mean	Std.
M1	3.65	1.22	0.56	1.85	0.45	0.41
M2	3.72	0.86	0.63	2.10	0.40	0.43
M3	3.32	0.91	0.78	2.67	0.57	0.62
M4	3.48	0.94	0.83	2.41	0.53	0.58

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 Table 3 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

Index	Service Name	Lower Frequency	Upper Frequeue	E (V/m)
I	Low Band	30 MHz	37.3 MHz	0.133

	FM Band	87.5 MHz	108 MHz	0.021

3	Air Band	108.1 MHz	136 MHz	0.022

4	Land Band-I	130.1MHz	173 MHz	0.021

5	TV VHF Band	173.1MHz	230 MHz	0.023

6	Laud Band-II	230.1 MHz	400 MHz	0.026

7	Land Band-III	400.1MHz	470 MHz	0.015

8	TV UHF Band	470.1 MHz	790.9 MHz	0.084

9	LTE800	791MHz	820.9 MHz	1.402

10	ETCÌ	821MHz	925 MHz	0.057

11	LTE900	925.1MHz	935.1 MHz	0.913

12	GSM900	935.1 MHz	961.0 MHz	2.048

13	ETC2	961.1MHz	1.805 GHz	0.147

14	GSM1800	1.805 GHZ	1.820 GHz	0.554

15	LTE1800	1.820 MHz	1.879 MHz	0.456

16	DECT	1.880 GHz	1.899 GHz	0.024

17	ETC3	1.899 GHz	2.010 GHz	0.067

18	UMTS2100	2.010 GHz	2.170 GHz	2.243

19	ETC4	2.171 GHz	2.399 GHz	0.034

20	WLAN	2.400 GHz	2.483 GHz	0.314

21	ETC 5	2.484 GHz	2.569 GHz	0.031

22	LTE2600	2.570 MHz	2.660 MHz	0.082

23	Residual services			0.598



24	Total			3.616

It is seen from Table 3 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:

ET=∑i=123(Ei)2(1)

where E_i is the electric field for i^th band. The other transmitters excluding 18 bands give rise to E₂₃. The contribution percentage (P_i) of each band is computed as in Eq. 2.

Pi=Ei2ET2×100(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%.

Figure 5

Pie chart of E

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

3 Analysis

Total E value of medium is calculated with Eq. 3 with the use of band selective measurements. In this equation, all service names’ E value will be represented with an index number (e.g. E₁₀ for GSM900) throughout the rest of the paper. The estimated total E of the medium (E_T) can be computed with Eq. 3 using the six bands which consist of 88.7% of total E.

E^T=E92+E112+E122+E142+E152+E182(3)

In order to evaluate the performance of the method Normalized Root Mean Square Error (NRMSE) is computed as follows:

NRMSE=1N∑i=1N(ET,i−E^T,i)2max(ET)−min(ET)(4)

where E_T,i is actual E value, Ê_T,i is estimated E, i is measurement location, and N is the number of measurements locations.

The NRMSE is 0.0729 between E_T and Ê_T for Eq. 3. In order to obtain lower NRMSE multilinear regression [16] was implemented and total E in medium is estimated as follows;

E^T=(0.01810+1.0448E92+1.2804E112+0.9814E122+1.3335E142+0.9655E152+0.9768E182)1/2(5)

NRMSE between between E_T and Ê_T is calculated as 0.0705 using this equation. Figure 8 shows estimated E values using Eq. 3, and Eq. 5, and actual E values of corresponding measurement locations. It is seen from Figure 8, Eq. 3 gives the best performance especially actual E values lower than 0.5 V/m, while Eq. 5 gives better performance for high E values. Therefore a new empirical E estimation model can be proposed combined of Eq. 3 and Eq. 5 and given in Eq. 6. The NRMSE is 0.0538 between E_T and Ê_T for Eq. 6.

Figure 8

Multilinear regression analysis

E^T=E92+E112+E122+E142+E152+E182E<0.5(0.01810+1.0448E92+1.2804E112+0.9814E122+1.3335E142+0.9655E152+0.9768E182)1/2E≥0.5(6)

4 Conclusion

In this study, for observing the change of E in Atakum district of Samsun, Turkey, three stage measurements were conducted. In the first stage, short term E measurements were taken at four different times and at 46 different locations. It can be seen from the measurements that E values may change with time and the measurement locations. It can be inferred from the measurements results that the maximum recorded E_max is 17.53 V/m while the maximum E_avg is 9.45 V/m which are below the limits determined by the ICTA and ICNIRP. It is also seen from the results that E_avg has increased within measurement periods. In the second stage, in order to define the main E source in Atakum district, band selective E measurements were performed at the same locations using the SRM 3006. An extensive analysis of band selective measurements demonstrates that the primary E sources in Atakum district are the base stations which use LTE800, LTE900, GSM900, LTE1800, UMTS2100 frequency bands, and 2100MHz has the most contribution to total E value with 43.6%. In the third stage long term E measurements were recorded to assess the changing of E during the day. It is seen from the results that the E level in the morning increases by 48.9% compared to the measurements in the afternoon. At the end of the study a tentative mathematical model was obtained to estimate E in the medium with an accuracy of up to 95%.

References

[1] ICNIRP Guidelines, Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic, and Electromagnetic Fields (up to 300GHz), International Commission on Non-Ionizing Radiation Protection, Health Physics 1998, 74 (4), 494-522Search in Google Scholar

[2] Information and Communication Technologies Authority of Turkey, Ordinance change on By-Law on Determination, Control and Inspection of the Limit Values of Electromagnetic Field Force from The Electronic Communication Devices According to International Standards, Law no.29497, 9 October 2015Search in Google Scholar

[3] Engiz B.K., Kurnaz Ç., Long-Term Electromagnetic Field Measurement and Assessment for a Shopping Mall, Radiation Protection Dosimetry, 2017, 175(3), 321-329.10.1093/rpd/ncw343Search in Google Scholar PubMed

[4] Kurnaz Ç., An Emprical Modelling of Electromagnetic Pollution on an University Campus, The Applied Computational Electromagnetic Society Express Journal, 2016, 1(2), 76-79.Search in Google Scholar

[5] Kurnaz Ç., Bozkurt M.C., Measurement and Evaluation of Electromagnetic Pollution Levels in Ünye District of Ordu, Journal of New Results in Science, 2016, 5(12), 149-158.Search in Google Scholar

[6] Engiz B.K., Measurement and Assessment of Long Term Electric Field Strength in Different Locations, International Journal of Advanced Research in Computer and Communication Engineering, 2016, 5(10), 455-458.Search in Google Scholar

[7] Kurnaz Ç., Engiz B.K., Measurement and Evaluation of Electric Field Strength in Samsun City Center, International Journal of Applied Mathematics, Electronics and Computer, 2016, 4(1), 24-29.10.18100/ijamec.271016Search in Google Scholar

[8] Kurnaz Ç., Engiz B.K, Bozkurt M.C., Monitoring of RF/Microwave Field Strength at Schools in a Pilot District in Samsun/Turkey, 16th Mediterranean Microwave Symposium (MMS-2016), 14-16 November 2016, Abu Dhabi, UAE10.1109/MMS.2016.7803786Search in Google Scholar

[9] Kurnaz Ç., Engiz B.K, Monitoring and Assessment of Electromagnetic Pollution in Samsun (Turkey), 39th International Conference on Telecommunications and Signal Processing (TSP-2016), 27-29 June, 2016, Vienna, Austria10.1109/TSP.2016.7760864Search in Google Scholar

[10] Mousa A., Electromagnetic radiation measurements and safety issues of same cellular base stations in nablus, Journal of Engineering Science and Technology Review 2011, 4(1), 35-42.10.25103/jestr.041.05Search in Google Scholar

[11] Seyfi L., Measurement of electromagnetic radiation with respect to the hours and days of a week at 100 kHz–3GHz frequency band in a Turkish dwelling, Measurement, 2013, 46(9), 3002-3009.10.1016/j.measurement.2013.06.021Search in Google Scholar

[12] Baltrenas P., Buckus R., Measurements and analysis of the electromagnetic fields of mobile communication antennas, Measurement, 2013, 46(10), 3942-3949.10.1016/j.measurement.2013.08.008Search in Google Scholar

[13] Koprivica M., Slavkovic V., Neskovic N., Neskovic A., Statistical Analysis of Electromagnetic Radiation Measurements in the Vicinity of GSM/UMTS Base Station Installed on Buildings in Serbia, Radiation Protection Dosimetry, 2016, 168(4), 489-502.10.1093/rpd/ncv372Search in Google Scholar PubMed

[14] http://www.pmm.eu/includes/sendfile.asp?nomep=Field_ProbesSearch in Google Scholar

[15] https://www.narda-sts.us/pdf_files/DataSheets/SRM3006_DataSheet.pdfSearch in Google Scholar

[16] Brown S.H., Multiple linear regression analysis: a matrix approach with MATLAB, Alabama Journal of Mathematic, 2009, 34, 1-3.Search in Google Scholar

Received: 2017-11-02

Accepted: 2017-11-22

Published Online: 2018-03-20

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Articles in the same Issue

https://doi.org/10.1515/phys-2018-0013

Keywords for this article

Electric field strength; electromagnetic (EM) radiation; EM measurement; base station; statistical analysis

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