U¿ytkownik "Rob" napisa³ w wiadomo¶ci
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Szczepan Bialek wrote:

"Howard K0ACF" napisa3 w wiadomo?ci
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"Szczepan Bialek" wrote in message
.. .

"The wire antennas used with crystal receivers are monopole antennas
which develop their output voltage with respect to ground. They require
a
return circuit connected to ground (earth) so that the current from the
antenna, after passing through the receiver, can flow into the ground."

I had a crystal radio & the antenna was a piece of wire hanging out of
it
& the radio was built in a wooden box & I could listen to it on the
second
floor of a wooden building & sitting on a wooden chair. no connection to
the ground (earth) as you say is required & the station I listened to
was
a daytime station located about 50 miles away...How did it work & no
connection to the ground (earth) as you say is required & no battery
power
& the crystal had a cat wisker for tuning...

Ian wrote:
"Normally there is a tuned circuit at the input, which consists of a
coil and capacitor in parallel. The DC flows through the coil.

At the output there either is a high-impedance magnetic headphone,
which conducts DC through its coil, or a crystal headphone with a
resistor in parallel for the DC path."

Next the DC flows into "ground":

NO NO NO NO NO!!!!

The DC flows in a circle inside the receiver!!!

When you see the schematic diagram of a working crystal receiver,
you can make a trip trough the diode, through other components in
the receiver, all conducting DC, back to the the point where you
started at the diode.

This path must exist and this is where the DC flows.

The path is the ground: "The use of the term ground (or earth) is so common
in electrical and
electronics applications that circuits in portable electronic devices such
as cell phones and media players as well as circuits in vehicles such as
ships, aircraft, and spacecraft may be spoken of as having a "ground"
connection without any actual connection to the Earth. This is usually a
large conductor attached to one side of the power supply "

When there is no such path, a DC voltage equal to the peak value
of the HF voltage will develop across the diode, the diode will
no longer conduct, and there is no more rectification. Hence the
receiver will not work.

This is not related to "ground". There must be HF voltage at
the input of the receiver, but it is not important if it is between
a monopole antenna and ground or between the poles of a dipole.

Each voltage disappear (leakage) with the time. That before diode and that
after. The leakage is always and everywhere.
The leakage is surface and humidity dependent.

You can even make a crystal receiver with a ferrite rod as an
antenna, which will operate without any ground.

Leakage do the work.
S*