"Jeff" napisal w wiadomosci
...
On 12/04/2012 09:41, Szczepan Bialek wrote:

So the earth is necessary in your radio for the static reasons.
In my also:
"In the lower half of the mast, there was a vertical steel tube, attached
to
the mast's outer structure with large insulators. This tube was grounded
at
the bottom, and connected electrically to the mast structure by an
adjustable metal bar at 328 metres.[2] This technique allowed adjusting
the
impedance of the mast for the transmitter and worked by applying a DC
ground
at a point of low radiofrequency voltage, to conduct static charge to
ground
without diminishing the radio energy. Static electrical charge can build
up
to high values, even at times of no thunderstorm activity, when such tall
structures are insulated from ground. Use of this technique provides
better
lightning protection than using just a spark gap at the mast feed, as is
standard at most mast radiators insulated against ground."
From: http://en.wikipedia.org/wiki/Warsaw_radio_tower

It seems to me that the same reasons were in Marconi times.

So I repeat my question:

""The necessity or utility of the earth connection has been sometimes
questioned, but in my opinion no practical system of wireless telegraphy
exists
where the instruments are not connected to earth."(Marconi in 1909).

It is still true?
S*



How many times do you need to be told? NO IT IS NOT TRUE, Marconi may have
been correct when he made the statement considering the equipment and
practices at the time, BUT he was not correct as a statement concerning
radio systems in general. Things move on. Your mobile phone has no earth
connection, satellites have no earth connection. Accept this and move on.

Radio on the Moon has the "earth connection". The Moon is smaller than the
Earth.
Do you think that "the earth" must be giant?

Your mobile phone has earth connection, radio on satellites and planes
have earth connection because they are on the chassis. Accept this and
move on.

Some antenna systems do have an earth connection, many don't.

All must have.

Some have them in order to work correctly, some have them for protection
against a lightening strike or a build up of static, some for both. Many
have no earth connection at all.

All must have for protection against the build up of static.
"Static electrical charge can build up to high values, even at times of no
thunderstorm activity,"
S*