Using the salt concentration of the Blackwater Estuary to aid radio transmissions


DXing in the Blackwater at goldhanger in 2013.jpgAmateur 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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