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Re: [TowerTalk] FW: [N3SH] Cell tower questions

Subject: Re: [TowerTalk] FW: [N3SH] Cell tower questions
From: Dave Fuller <>
Date: Wed, 10 Aug 2005 15:08:21 -0600
List-post: <>
I guess I can take a shot at this.  I worked as an engineer for PCS 
companies for 8 years doing system design.   As the lead engineer of 
many markets I did RF strength calculations on hundreds and hundreds of 
cell sites.   I can tell you that if the site antennas are 65 feet or 
more off the ground the RF exposure directly under the antennas is 
typically less than 1% of the FCC limits for long term RF exposure.  The 
same RF exposure rules apply to amateur operations as well although 
there are slightly different limits based on frequency.   If you are  
even 1/10 of a mile from cell site you will receive thousands of times 
less exposure to RF field strength than you would get using your own 
cellular or cordless telephone in your own home.   Without running the 
calculations I would expect more than 10,000 times less signal from the 
cell site at a half mile than the exposure from your own cordless 
phone.  The worry is not even a reasonable consideration.   The 1 over R 
square rule really gets huge at those distances.   A few times I had the 
expensive test equipment to measure the actual field strength from a PCS 
system and the only place I could get a signal to exceed the limits for 
long term exposure was typically less than a foot from the antenna 
directly in the beam pattern with the transmitter running at maximum 
output..   No.... that equipment to make those measurements is not cheap 
or simple to do.   I also was able to exceed the limit with my mobile 
ham antenna on my car running 100 watts on HF but only inches from the 
antenna, even a few feet from the antenna was safe.

There are quite a few documents out there that show that  in a typical 
city the RF field strength in your neighborhood from all other RF souces 
such as pager, broadcast, two-way, police services, TV etc..all add up 
to hundreds to thousands of times more RF already than a cell site would 
ever contribuite to a neighborhood even if you lived right next door to 
it.   I used to tell people that suppose 100 cars per hour drive down 
your street.....if a cell site is added it might add one more car per 
DAY to the traffic already present in the neighborhood.

In short, a cell site 1/2 mile away is not even worth the effort to be 
concerned about it.   Still there are people out there who hate cell 
towers just like ham towers and they like to bring up the RF radiation 
issue to generate anti tower support, even though simple physics shows 
that there is clearly little additional exposure in our communities due 
to the addition of cell sites that blanket our communities.

 The cell/PCS systems are the ultimate in QRP application of radio and 
using the minimum power levels to accomplish the communication goals at 
every instant..   The systems all must work on the minumum power for 
each call to be served and there are elaborate software schemes that do 
closed loop power control to ensure that the minimum power is used at 
every instant on every call to maintain your phone call.   You can see 
simple evidence of this when you compare the battery life of the old 
analog cell phones to the new digital cellular or PCS phone.    If your 
new small PCS/Cellular phone ever roams on an old analog network you 
find out quickly about the closed loop power control systems (or lack 
of).   Analog cellular is quickly on it's way out and all the new 
systems are safer and more reliable than ever. 

-Dave WD7Z wrote:

>Can any one on TT answer Todd's questions?
>Larry K3VX
>----------------------  Forwarded Message:  ---------------------
>From:    Todd Wade <>
>Subject: [N3SH] Cell tower questions
>Date:    Wed, 10 Aug 2005 17:29:49 +0000
>I have a co-worker who is considering a move to a new
>home.  The house he's looking at is within a 1/2 mile
>of a cell tower that is approx. 75-100 ft.  His wife
>is raising concerns over RF exposure. 
>Since I'm no expert in microwave (or any other RF
>subject for that matter!), I told him that I would ask
>a few questions of the group.  
>1. What sort of exposure would someone have at that
>distance?  What are typical power numbers from cell
>sites?  Would there really be any significant RF at
>the house's location?
>2. Is there some kind of cheap way that they could
>take field strength readings around the house that
>would give them a feel for their exposure?  I realize
>that some kind of receiver would work, but they want a
>simple scheme, be it something they borrow or buy, or
>be it from someone doing the survey using their own
>Thanks for any help.  He wants to put his wife's
>worries to rest fairly soon.
>Todd - W8LEV
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