It never ceases to amaze me how inventive the radio amateur can be. I was recently looking around for some unusual antenna designs when this came to my eyes. An antenna made from water!
Now I know some (most?) of you may be skeptical, but think about it. Wet earth is a better ground than dry earth and, if you live overlooking the sea, a wire into the water is about the best you can do for a ground!
I have previously read an article about transmitting through a piece of wet string (someone heard the "Wet string is better than that antenna" and decided to put it to the test). It was discovered that wet string (dampened with a salt solution) does, in fact, work reasonably well as an antenna but you have to keep dampening it as the wind and RF dry it out.
Anyway, I digress. The point of this experimental antenna project is to make an antenna out of water.
When David started his experimentation he contacted an electrical engineer and asked him, "What is the best ratio of water-to-salt to make the highest conductivity of saltwater to make an antenna?"
The reply was, "That will not work as an antenna, RF energy would only radiate through metals."
To which David countered, "I have just talked to Australia on my saltwater antenna."
The surprised engineer replied, "I'll be damned!"
David reports that his tests using a water filled tube as an antenna consistantly out performed 4g copper wire of the same length when suspended side by side and using the same equipment for testing.
His research has shown him that the amount of salt dissolved in the water had a direct relationship with the increased conductivity of the water. He further notes: "you cannot have too much salt in the water". I'll give you his directions to make one of these but bear in mind that for some of his experiments he used salt water filled garden hosepipe. Just let the planners complain about you hanging your hose up to drain (even though you know it's full of water and stoppered!).
Over to David for how to make and maintain such an antenna:
Firstly, copper can be substituted by a "high nickel blend" of stainless steel. This will minimize corrosion. If using copper, the threaded PVC cap allows for easy cap removal. Thus allowing you to inspect and / or clean the copper probes. I have found it best to clean them once a month, and to use fine steel wool. Be sure to top-off the saline solution in the tube, and put on fresh teflon tape before replacing the threaded cap. Now, go back on the air and have a blast!
This IFA is a long way from being perfected! Variations in many aspects of the antenna may show improvement in performance. Yet to be tested are other Ionic Fluids, some more conductive than others. However, some Ionic Fluids are dangerous, and expensive. There are even different kinds of salts that have yet to be tried, such as Copper Chloride. Using saltwater is the real meaning of "Homebrew". It's easily available, quite safe, and easy to prepare.
Thanks for your hard work David, there's plenty there for people to work with / on for assembling their own "water radiator". I'm just wondering that if a different type of salt is used, and the colour of the water changes as a result, could it be called a "Dye Pole"??
The original concepts and details about this antenna can be found at:
Ionic Liquid Antenna Concept by N9ZRT
(dated 2002, most of the links seem broken though) and
The Ionic Fluid Antenna
(undated, no links).