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From: David Jefferies
Date: 26 Nov 2002
Time: 06:21:52
Remote Name: 195.92.168.164
I have just been asked to comment on any possible problems with safety of a mobile phone mast in a Shell petrol station hoarding, at a height of 4 metres and a range of 60 metres from someone's living room. We are told it radiates 800 watts, presumeably into an omnidirectional pattern, at a frequency of 1.8 GHz.<><><> Allowing for a dipole radiation pattern gain of 1.65 numerical in the azimuth plane, that makes (I think) the power density at a range of 60 metres (well into the far field) of around 30 milliwatts per square metre, or 3 microwatts per square cm. Here there is no allowance for multipath or absorption in obstacles.<><><> Now if we compare this with the likely power density from a mobile phone handset radiating 100 milliwatts into a head area of 20cms by 10 cms (yes these are questionable assumptions but not unreasonable) we arrive at a power density of 500 microwatts per square cm into the head, which is a factor of 167 times stronger.<><><> This little calculation must be comforting to those Hams who have neighbours who question the safety of their transmitter installations at the same time as talking to their mates on their mobile phones. :-) <><><> David Jefferies.