Ionic Fluid Antenna.

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:

Materials Required:

2 inch x 10 foot PVC pipe [Any wall thickness]*
Two female 2 inch PVC threaded sleeves*
Two male 2 inch PVC threaded caps with square, "wrenchable", type ends.*
PVC glue [For leak prevention]
One roll of Teflon (plumbers PTFE) tape [For leak prevention]
A small portion of fresh Silicone [For leak prevention]
6 inches of heavy copper braid, 4 or 6 g [For RF input/probes]
8 inch or so medium weight rope [For suspension system]
2 inch stainless hoseclamp [For suspension system]*
3 gallons of water**
Several pounds of granulated table salt [5-10 pounds]***
25 feet [or so] of rope [For suspension system]
Hydrometer and clear measuring cylinder [Optional]

*To make a "Fat Boy" [10 foot x 4 inch IFA], substitute all 2 inch items to 4 inch.

**For a "Fat Boy", prepare with 6+ gallons of water.

*** For a "Fat Boy", prepare with 10-20 pounds of salt. Granulated dissolves best.

Construction:

Take the 10 foot PVC pipe, prepare ends by sanding where the female sleeves will go on both ends.
Glue female both ends on 10 ft PVC.
Solder 1 inch of one end of the copper braid. Solder it as solid as possible to prevent water coming through the strands.
Bend the braid into an "L", with the soldered end being the short end of the "L". This portion will stick out of the PVC cap.
Drill a hole in one of the squared wrenchable cap ends. Make the hole on the side, so that when the antenna is standing on it's end, there will be no pressure on the protruding braid [RF connection].
Insert the braid into the hole, so the unsoldered end comes out to the inner-side of the cap.
De-braid the copper braid, making it like a spider. Bend the strands [Hence called, "probes"] so they "sit" on the inside of the cap. Bend the tips inward, so when the cap in inserted into the tube [Antenna], they will not snag.
Silicone the inside very liberally, avoiding any silicone from getting on the probes. [Let it cure for several hours]
Silicone the outer portion of the drilled hole, avoiding the silicone from getting on the RF connection [Soldered braid]. [Let it cure for several hours]
Liberally, teflon tape wrap the male thread on the cap end with probes, and snug into the female fitting [Base of antenna].
Heat 3 gallons of tap water to a boil. Pour salt into the water and stir continuously until no more salt will dissolve. Extra salt will fall to the bottom. Let cool.
Note: I have successfully used rock salt and found it to dissolve "OK" in hot water, when stirred. I keep a 50 gallon plastic garbage pail outside, with my saline solution in it. When making a large batch, I have run a garden hose from my hot water tap into the saline reservoir, and stirred in the rock salt, mixing the batch with a canoe paddle. The reservoir, at this writing, is sitting in 15 degree F weather, and looks as clear and ice-free as a summer swimming pool!

Set 10 foot PVC on a firm seating, at a 45 degree angle, with the probe end down. Best to do this outside. Note that spillage will kill grass.

Pour the saline into the tube until full.

Teflon tape other male cap. Snug into place.

Take short rope and tie a knot in each end.

Using hose clamp, clamp short rope to top end of antenna [Top is opposite end of probes].

Find overhang, and mount suspension rope.

Suspend antenna, checking for leaks.

Tune and go on the air.

Maintaining your copper probes:

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!

The experimenting continues:

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).

Highfields Amateur Radio Club
Constructors Corner.