[amsat-bb] RF Exposure

[David Reinhart <wa6ilt@xxxxxxxxxxxxxxxx>]

I was going to present a paper on this at the Symposium this October in
Atlanta, but it begins to look like I may not make it so I'll throw out
the problem here.

Sorry to be a kill-joy, but a lot of people hoping to use AO-40 in
condos, with attic mounted antennas, etc., need to be aware that they'll
probably be breaking FCC regs if they actually get on the air.

Many people think that the RF exposure rules the FCC put in place a few
years ago are way too conservative or even just plain nonsense, but
there they are.  If you run a quick and dirty analysis (there's an RF
exposure program for W32 on qrz.com written by our own Stacey Mills)
you'll see that the uncontrolled exposure distance can easily proclude
(for example) balcony mounted transmit antennas on U or L band.  To
comply with the rules, people with ground mounted antennas probably need
something like a string circle around their antennas at the uncontrolled
exposure distance with RF exposure warning signs.  I really don't know
what the minimum requirement are for signs and access control.

Heck, I discovered that my 70cm output during terrestrial contests (when
I run lots of power) wasn't meeting the criteria for uncontrolled
exposure.  That's with an antenna more than 40 feet off the ground 12
feet away from the house.  The house is a raised ranch and one corner of
the upper level ends up being too close.  It just so happens that's
where the master bedroom is!

All these comments are based on my preliminary work and should be looked
at in that light.  Nevertheless, I am sure that some of the
installations people have discussed here won't meet the requirements and
this is a factor that needs to be considered.  At the very least you may
end up with ticked-off neighbors and at worst you could be harming
someone's health.

David Reinhart
wa6ilt@amsat.org

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