[Fwd: Re: A radio can NEVER work without a ground?]
andre.kesteloot at verizon.net
Sun Jul 15 17:16:08 CDT 2007
hal feinstein wrote:
> Another of those glaringly obvious questions:
> Proposition: In an idea system we know that radio reception can only
> occur when a receiving apparatus conducts radio signals
> from its antenna, through intermediate circuits, to ground.
that is not, unfortunately, a true proposition, or put another way, it
is not properly formulated.
One needs a radio signal to be induced in the input circuit of a receiver.
Traditionally, when one used external "receiving aerials", the antenna
was connected to one side of a coil, the other side being indeed
connected to "ground".
A RF potential difference existed between the aerial and the ground, and
was coupled, via the coil, to the rest of the receiver circuitry.
The input circuit, however, can also consist of a tuned circuit such as
a length wire wound around a ferrite rod, and tuned with a capacitor.
Magnetic lines of force passing through the ferrite rod and the coil
will induce a RF difference of potential across the two ends of that coil.
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