Tuesday, November 22, 2011

Radiation from Cell Towers --By Prof. Girish Kumar

From the Reports of Prof. Girish Kumar, IIT , Mumbai

A GSM 900 base station antenna transmits in the frequency range of 935 - 960 MHz. This  frequency band of  25 MHz is divided into twenty sub-bands of 1.2 MHz, which  are allocated to various operators. There may be several carrier frequencies ( 1 to  5 ) allotted to one operator with upper limit  of 6.2 MHz bandwidth . Each carrier frequency may transmit 10 to 20 w of power. So , are operator may transmit 50 to 100w of power & there  may be 3 to 4 operators on the same roof top or tower, there by total transmitted
power may be 200 to 400w. In addition, directional antennas are used, which  typically may have a gain of around 17dB( numeric value in 50 ), so effectively, several Kw of power may be transmitted in the main beam direction.


more write in next blog --!

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