Using the salt concentration of the Blackwater Estuary to aid radio transmissions
Amateur radio enthusiasts DXing
occasionally use the exceptionally salty water in the estuary to enhance their radio
transmissions. The term DXing comes from, telegraphic shorthand for "distance"
which is DX.
The
enthusiasts set up potable transmission equipment on the Spit at the Shoe,
which is just yards from where the seasalt is extracted. The explanation of why
salt water benefits this activity is complex...
The
electrical conductivity of pure distilled water, that contains no dissolved
solids, is zero and it is effectively an insulator, and the conductivity level
of water depends entirely on the quantity of dissolved salts and other
minerals, and is directly proportional to the level of salt, (sodium chloride)
dissolved in the water.
When
using a vertical aerial for transmission and reception, the vertical conducting
section functions as one half of a dipole, the other half is dependent upon the
conductivity of the medium below, beit earth or water, and the aerial
efficiency and equipment performance is dependent on what is below. High
conductivity in saline water permits Radio Frequency (RF) currents to flow in a
"ground plane" and uses much less power than a typical inland earth
location.
Shipborne
short and medium wave radio tranmitters have benefited from this effect for
many years, however it has only been in recent years that equipment available
to land-based amateurs has become small and portable enough to take advantage
of this phenomenon.
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