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Take the Myth out of Facts

Many myths concerning the safety of people living close to cellular BTS towers are circulating. According to the stories, all cellular RAN installations are suspect, chiefly the antennas employed. According to this scietifically unsupported approach, the larger the antenna and its gain, the more dangereous it is to people.

Inorder to separate the facts from the myths, we would like to call your attention to the article below written by the distinguished international expert on RF hazards, Dr. Haim Mazar, former head of RF Spectrum, Licensing and Monitoring Division at the Israel Ministry of Communications and Vice Chair ITU-Radio Study Group 5 (terrestrial services).


Myths and realities


Myth: The construction of a site antenna in one’s neighborhood should be of RF human exposure concern to people of that neighborhood.


Reality: Quite the opposite. As use of handsets is total, the limiting factor in terms of EMF exposure is the transmissions from the handset (uplink). This is the case in view of its physical proximity to the user's body. The handsets transmissions are power controlled, such that the handset does not transmit higher power than what is necessary to maintain reliable communications. Closer to the site the handset transmits less power.


Myth: The higher the number of site antennas in each area the higher the EMF exposure.


Reality: Not true. In reference to the exposure from the handset see the above; due to the profusion of sites, the handsets are closer to their corresponding base station and emit less. For radiation from the site antenna, the transmission levels are such that they should allow quality of service at the cell boundaries. The power density attenuates as the square of distance in free space and with a higher exponent resulting in higher levels at the inner areas of the cell. The smaller the cells the smaller is that extra exposure levels in the inner parts of the cell.


Myth: The larger the dimension of the cell site and antennas, the higher the exposure.


Reality: Not true. Antennas are made big in order to get higher gains of main beams. As a result, the field strength (and power density) in the area close to the antenna is reduced; achieved due to the sidelobe in elevation.


Myth: An antenna erected on the roof causes maximum exposure inside the building underneath.


Reality; Not true. Antenna transmits horizontally (or some small downtilt) such that directly underneath the transmissions are much reduced. Moreover, a concrete roof is a quite strong attenuator of EMF.


 Conclusively, the use of VEGA very high gain narrow beam antennas on cellular towers actually lowers the exposure to possibly harmful radiation.