> You may be overlooking the fact that the stated antenna pattern is only
> valid when far away from the antenna.

Maybe not so much overlooking as getting a feel for the overall power of the
beast. One is liable to be in the near field at the range he was taking
photos at. If instead we take the opposite extreme (also incorrect) and
assume that the power was radiated half isotropically - ie linearly in the
whole direction then one is still standing in the lair of a 400 kW beast.
Taking inverse square law drop off (also incorrect here) and comparing with
a 1 watt transmitter - one would have to be sqrt(400,000) = 600 times closer
to get the same result. If the photo was taken from 200 metres away (can't
recall the picture well) that would be the same as placing the camera within
1/3 of a metre of a working 1 wat transmitter aerial. Probably OK but if it
did cause problems one would not be surprised. If though there is any sort
of gain over isotropic where you are standing due to a lobe etc then the
situation gets worse. I suspect the transmitter is at least a likely
contender for the caera's demise.

> Also, it would have to be a mighty fast SCR to respond to GHz range
> signals, wouldn't it?

I think you are liable to get bulk recitification of the power signal and
the resultant DC voltages can then play such games as they can find. The
effective diode(s) doesn't have to be optimised for th egHz range to still
work there.

Maybe we should do some more research. Anyone live near Canberra and have a
few spare digital cameras to spare ?



        RM






>
> Sean
>
> At 11:50 AM 5/30/2002 +1200, you wrote:
> > > I'm compelled to state that I *seriously* doubt personnel
> > > were allowed anywhere near where a 'personnel hazard'
> > > could possibly exist and I also doubt that the 'sidelobes'
> > > at distance from such an antenna would contain enough energy
> > > to damage electronics as well ...
> >
> >
> >You may be right.
> >But there is an awful lot (technical term) of power involved.
> >Antenna gain is 40 million (75 dB) and transmit power is 400 kW so that's
16
> >Terrawatts (16,000,000,000,000) EIRP.
> >
> >Wouldn't need to much of a sidelobe to do quite some damage. All the
camera
> >needs is for some highish impedance point to rise to a voltage somewhat
in
> >excess of local supply voltage and the energy from the camera supply
could
> >do the rest - SCR latchup or something similar by a normally never biased
on
> >pathway.
> >
> >
> >
> >         RM
> >
> >--
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> >ways.  See http://www.piclist.com/#archives for details.
>
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