Earth Dipole

[Phil]

The security of all forms of wireless communication can be compromised in surprising ways. Some years ago I built a portable VLF receiver with a magnetic (ferrite coil) antenna. It clearly received sferics, whistlers, the washing machine motor from the end of the garden, and gave advance warning of the arrival of the electric milk lorry as it turned the end of the road.

One weekend morning I switched it on and clearly heard the Voice of God - and, more to the point, she was talking directly to ME. It took a short walk to discover that I was eavesdropping into the hearing aid induction loop at the Baptist Church nearly half a mile away. Disappointment and relief in equal measure.


Phil M1GWZ



On 21 Jul 2013, at 20:55, Alberto di Bene wrote:

> On 7/21/2013 8:21 PM, Mike O'Dell wrote:
> 
>> If i remember it right (50-50 chance),  for "transmitting", it was basically a transistor audio
>> amplifier driving a filament transformer backwards as a step-up output transformer.
>> the "output" was fed to a pair of spikes pushed into the ground about 20 feet apart.
>> in "receive" mode, the amplifier was fed from the spikes with some extra voltage
>> gain.
> 
> When was young (many eons ago...) I used this method to communicate with a friend,
> also interested in radio. We didn't have yet a license, so we resorted to this trick to 
> talk each other. We were absolutely sure that nobody could hear us, so we were, how
> to say, a bit free in our talks, especially when commenting the virtues or lack thereof
> of the girls of our entourage...
> 
> Then one day we were told that in the local cinema hall, during the pauses of the 
> movie, our voices could be clearly heard... and with them, all of our comments about 
> our girlfriends... a bit embarrassing, to say the least... I lost the friendship of some 
> girls, but at the same time made positive steps towards those of whom I had appreciated
> the.... virtues....    :-) 
> 
> 
> 73  Alberto  I2PHD
> 
> 
> 
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