In article .com,
"RHF" wrote:

In article
,
Telamon wrote:

If you connect the radio ground to the other half of a dipole or other
Hertzian type antenna it should reduce common mode pickup, which is the
main mode of local noise pickup.

I'll explain why this is if anyone cares to know.


I will take you up on your offer, please enlighten
and educate me ~ RHF

Snip

A portable using a whip antenna or using a single wire extension is a
Marconi type, which is a common mode voltage antenna. Locally generated
noise is picked up best by this type of antenna.

The whip or extension wire picks up common mode energy, generated nearby
or from a distance, which travels across the radio input impedance into
the radio chassis return. If you hold the radio or if it is plugged into
an AC converter supply then you and the mains become part of the RF
return. The radio chassis return, you or the mains look like a low
impedance path for the RF to go into so the circuit is the one element
generating a voltage with the RF current across the radios input
impedance into a low impedance ground or return.

This is contrasted with a Hertzian balanced antenna where the RF current
travels from one element to the other through the radios input impedance.

Here locally generated noise tends to couple to both elements more or
less equally so a potential voltage difference does not appear across
the radios input impedance for the local noise source energy. However, a
distant EM waves at 1/2 wavelength of the dipole or smaller will
generate a potential voltage between the two elements, which causes RF
current to flow through the radios input impedance.

This action between local and distant energy on a Hertzian type antenna
is situationally dependent but should show a marked improvement over a
Marconi type antenna for distant signal to local noise. This improvement
is best shown with the portable on batteries so the antenna arrangement
is best balanced. Using a AC supply will have a tendency to unbalance
the Hertzian antenna.

--
Telamon
Ventura, California