Iranian Journal of

Background and Objectives: with the developments of technology, contact with various frequencies of electromagnetic fields ( EMF ) has significantly increased, while the abundant benefits of using microwaves in routine life cannot be neglected. During recent years there have been reports of adverse effects caused by contact with electric and magnetic fields of these waves that spread from BTS antennas. The purpose of this study is the measurement of microwaves spreading around BTS antennas in Tehran.
Materials and Methods:  according to the location of BTS antennas in Tehran , power density of electromagnetic waves around 63 antennas in near and distant fields in different distances was measured. The measurements were performed using the standard method of IEEE Std C95.1 by Hi-4333 device .in order to analysis  data we used spss 16 and descriptive and deductive statistical tests.
Results: results of this study show that in the near field, with increase of distance  from the foot of antenna , the  average power density of electromagnetic waves increase in a way that in the distance of 10 meters from the antenna foot , the increase of average power density is hardly conceivable and from 10 to 15 meters distance is perfectly noticeable. But in the distant field, with increase of distance from 20 meters, the average power density of the electromagnetic waves decreases and from 100 meter and further, the gradient of the diagram will get almost linear and the rate of power density reaches the base limit in a way that with the increase of distance there would be no significant decrease.
Conclusion: All the measures of power density of electromagnetic waves caused by BTSs are about 0.06% of recommended measures of environmental standards and 0.0000013% of occupational standards. The results of this study are close to the results of other studies.

Background and Objectives: Due to the increasing use of mobile phone in recent years, the number of BTS antennas has also increased. .Proliferation of BTS antennas in cities and villages, and perpetuation of encountering with waves from one side and  increasing the anxiety of many people in encountering with their waves from the other side convinced more investigations in this field. Therefore, the purpose of this study was to investigate  the propagation of microwave around the BTS antennas of Maragheh and to compare power density measurements  with allowable environmental standards.

Material and Methods: In this research, the frequency of BTS antennas was determined through field monitoring. Then, measurements were performed using a calibrated Spectran 4060 and the standard method IEEE Std C95.1 was adopted in close and far fields from each antenna. Then, the obtained data were analyzed  after entering to SPSS environment. In this study, the Kolmogrov-Smirnov test, Kruskal-Wallis, and Mann-Whitney tests were used.

Results: This research found  that in both  Irancel and Hamrah Aval operators, the power density increased with distance in close fields and decreased in far fields. Moreover, at the distance of 20 meter, the maximum value of power density was measured. Significant difference between these distances was observed (P-value ≤0.05).

Conclusion: Out of 1804 cases in far and close fields, the highest power density measured at 900 MHz band was 4.51 mW/m²,  which is in accordance with 0.1% permissible exposure.