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Liquid Metal Antennas

from Michael Lake - KD8CIK on February 28, 2006
Website: http://www.hamdomain.com/
View comments about this article!

There is a new way to experiment with antennas, using a non-toxic liquid metal called Galinstan.  This Gallium, Indium, and Tin based conductive liquid allows for adjustable and switchable  antenna elements.

I have already experimented with the following:

1.  Using air pressure to force the liquid metal up plastic tubing, giving you adjustable length elements.  An entire yagi beam antenna could be adjusted in frequency by putting liquid metal tubes on the element ends.  My prototype liquid metal antenna can adjust to the 2m, 220, and 440 bands plus has a contact near the top for a fixed 6m connection.

2.  You can make a stretchable elastic wire.  Liquid metal is placed in a rubber tube with contacts on the ends.  The advantage of making a stretchable elastic wire with liquid metal is that the surface is continuous - it has a predictable impedance.

3.  Air, gas, or non-conductive liquid can be used to push liquid metal into contacts.  For example, you could switch sections of an antenna using air lines.  It may be much cheaper than doing it electrically.  I used an aquarium air pump and tubing.

4.  I have tried putting a balloon inside a balloon, with liquid metal in between the balloons.  When you inflate the inner balloon the liquid metal forms a thin shell between the balloons.  This gives you an air pressure adjustable antenna element.

Already there are patents for using liquid metal as an adjustable ‘'Conductive fluid ground plane`’ and similar ideas.  Now is the time to experiment with using this non-toxic liquid metal.  You can obtain it from several places on the internet depending on the quantity that you want.

I saved the downside for last.  The Gallium based liquid metal has a problem sticking to surfaces.  It does not stick in the Geratherm thermometers that use it because they claim to use a thin layer of oxide (or ‘’rust‘’).  From my experience, oxide actually appears to be part of the problem.  Protecting the surface with a thin layer of oil kept it from sticking for longer.  Perhaps someone can find the ‘’magic’’ solution…

However, it does not matter if the liquid metal sticks in elastic stretchable wire or balloons.  That is why I am already planning to use a balloon with a layer of liquid metal to tune a multi-band antenna I have yet to finish.  Remote adjustment is important to me because I am paralyzed and have trouble getting on my roof (it’s another story).

More information is on my website:
http://www.hamdomain.com/lm-antenna/

Mike Lake - KD8CIK

Member Comments:
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Liquid Metal Antennas  
by N3UMH on February 28, 2006 Mail this to a friend!
Pretty cool; like a liquid SteppIR...

Galinstan is pretty expensive in quantity though, isn't it?

Probably going to rule out a liquid metal HF array.

I work with lots and lots of sodium metal, but there's a more serious weatherproofing problem there...

73 and good experimenting,

Dan,
N3OX
www.n3ox.net
 
RE: Liquid Metal Antennas  
by KC9HVN on February 28, 2006 Mail this to a friend!
" work with lots and lots of sodium metal, but there's a more serious weatherproofing problem there... "

Lol! yep, that would make for some excitement up on the roof.

73's
m.
AB9LZ
 
RE: Liquid Metal Antennas  
by K5DVW on February 28, 2006 Mail this to a friend!
Wow, where do you get this stuff? Curious over what temperatures it's liquid?
 
RE: Liquid Metal Antennas  
by N3UMH on February 28, 2006 Mail this to a friend!
I think galinstan is liquid down to -19C

Upper limit boiling...

I checked out KD8CIK's site more; seems it's $40 for 1/2oz. but he used small tubing to make relatively long elements.

It's too bad sodium is so reactive; it's only $2/liter in bulk, and it's the best electrical conductor of any liquid. Of course, it doesn't melt until 98C, so you'd have to heat the antenna!!!

Dan,
N3OX
 
RE: Liquid Metal Antennas  
by W9PMZ on February 28, 2006 Mail this to a friend!
Next thing you know we will have liquid metal terminators...........

73,

Carl - W9PMZ
 
RE: Liquid Metal Antennas  
by K0BG on February 28, 2006 Mail this to a friend!
Sort of puts new meaning in the word quanta.

Alan, KØBG
www.k0bg.com
 
Liquid Metal Antennas  
by ARRLBOOSTER on February 28, 2006 Mail this to a friend!
I built a log periodic out of this stuff! It was a real chore. It is expensive, cost me about $49,000.oo.
I found that the cold-soldering system worked the best for all you do it your selfers.
 
Liquid Metal Antennas  
by N3AIU on February 28, 2006 Mail this to a friend!

Aren't the StepIR antenna people already thinking about making a multi-band VHF/UHF antenna? It seems that it would be a much more cost-effective solution.

73, Nick N3AIU
 
RE: Liquid Metal Antennas  
by WI7B on February 28, 2006 Mail this to a friend!

Michael,

A number of studies on electromagnetic conduction in Galinstan have be performed. That is because of the interest in understanding effects observed during magnetic induction melting of refractory metals.

Most recently Jens-Uwe Mohring has looked at the dynamic behavior of Galinstan under the influence of RF upto 50 KHz. It turns out that critical induction currents occur around resonance that not only generate standing waves, but "pinch" regions. These "pinch" regions form little cusps on the surface of the Galinstan and are stabilized by the RF field into "channels".

Since RF works specifically on the surface of Galinstan, the formation of these "channels" leads to dynamic instabilities in the conductor. Also check out the work of Y. Fautrelle and his analysis of these instabilities.

Not saying this will limit Galinstan's application to HF antennae, but these LF studies are worth some understanding before one would apply to much resonant high power to a Galinstan surface.

73,

---* Ken
 
RE: Liquid Metal Antennas  
by N6AJR on February 28, 2006 Mail this to a friend!
I think this would get pretty heavy in any appreciable length,, I'll keep my steppir, thanks..
 
RE: Liquid Metal Antennas  
by KD8CIK on February 28, 2006 Mail this to a friend!
I forgot about the pinching effect - a similar thing happens in electrical plasma. However, I do not expect it to be significant in my experiments. It is because of the weight and surface contact.

The force from the pinching effect is also proportional to current, so problems are more likely at higher power levels.

Mike Lake - kd8cik
 
Cheaper liquid metal & safety  
by KD8CIK on February 28, 2006 Mail this to a friend!
According to a document by Cadwallader called "Gallium Safety in the Laboratory", they made a liquid metal like Galinstan for 1/10th the small quantity cost. Their document is also good for safety. Search for "Gallium Safety in the Laboratory" in Google, etc.

Remember that the RF surface effect (or skin effect) keeps the current on the surface. That is another reason why I have tried thin layers in balloons, or using flat tubing. This can save considerably on costs.

Mike Lake - kd8cik
 
RE: Cheaper liquid metal & safety  
by N8BOA on February 28, 2006 Mail this to a friend!
What about a high power lasar that ionizes the air so that it then conducts RF. High wind could be a issue as well as homeland security
 
Liquid Metal Antennas  
by KZ1X on February 28, 2006 Mail this to a friend!
If you make one, Arnold Schwarznegger will be sent back via a time portal to destroy it.
 
RE: Liquid Metal Antennas  
by KC8VWM on February 28, 2006 Mail this to a friend!
Keep thinking like this.

Now you have me wondering about a circulating liquid metal heatsink cooling system for an amplifier.

Goodbye noisy fans.. Hello liquid metal!

Hmmm. A liquid metal antenna for mobile operations...?

I can see it now,.. A single translucent rod filled with liquid capable of covering everything from 15 meters to UHF frequencies and operated by your vehicles built in air vacuum system. Look ma.. no motors to wear out!

Could liquid metal somehow be injected into coaxial cable and used as shielding ?

Finally, a very flexible hardline!

73 Charles - KC8VWM
 
RE: Liquid Metal Antennas  
by NS6Y_ on February 28, 2006 Mail this to a friend!
Still not as cool as using a Home Depot motorized tape measure as your own adjustable vertical.
 
(re:) Liquid metal heatsink  
by KD8CIK on March 1, 2006 Mail this to a friend!
Liquid metal has been used for cooling applications, it has a high thermal conductivity.

The hazards are these: 1. It is electrically conductive - leaks can be bad for electrical circuitry. 2. It slowly dissolves into some metals, aluminum is the one it attacks most. (You can in theory dissolve a piece of aluminum in half with liquid Gallium or Galinstan.) 3. For good thermal conductivity it must be kept free of oxides.

A layer of a Gallium resistant metal would be one way to protect an aluminum heat sink There are reports of aluminum in a computer heatsink rapidly dissolving before a persons eyes. I have tried to get the liquid metal to attack aluminum myself and it was annoyingly slow and weak. Weeks later I am waiting for an effect on the end of a freshly cut 3/16 inch aluminum wire. I did dissolve aluminum foil after a few hours…
 
Whole new meaning to ON THE AIR  
by K6JEB on March 1, 2006 Mail this to a friend!
I love it. With the air pressure-created antenna you mention on your site, it gives a whole new meaning to "ON THE AIR"

Only issue I could see is when there are weather changes, there may be enough of a change in the ambient air pressure to cause some changes in the point of resonance. But this could easily get 'blown away' by just adding or subtracting air pressure in the antenna element tubes.

hi

73 de K6JEB
Jack
www.k6jeb.com
 
RE: Whole new meaning to ON THE AIR  
by KA5N on March 1, 2006 Mail this to a friend!
I thought that this article was scheduled for the the 1st of April.
 
RE: Whole new meaning to ON THE AIR  
by WB2GOF on March 1, 2006 Mail this to a friend!
I thought Galinstan was a small Islamic country to the southeast of Russia...
 
Liquid Metal Antennas  
by KE4ZHN on March 1, 2006 Mail this to a friend!
Interesting. The only thing I see wrong with this approach is, youd still need some sort of pumping system to work the elements. To me this would cancel out any advantage youd gain from not using a motor to extend and retract the elements. If anything the plumbing and pumps required would most likely be more complex than using a simple motor to do the same thing.
 
Liquid Metal Antennas  
by KI6LO on March 1, 2006 Mail this to a friend!
When have had liguid(y) antennas for a long time in the Mojave desert. Aluminum gets really hot and sorta limp in August every year, around the same time the mercury boils and the asphalt gets boggy. Everything related to antennas is way to hot to handle at 115+ degrees F.

 
RE: Liquid Metal Antennas  
by K8MHZ on March 2, 2006 Mail this to a friend!
" If anything the plumbing and pumps required would most likely be more complex than using a simple motor to do the same thing."

A big syringe for veterinary purposes would suffice and they are cheap.

I think the concept is fascinating, myself.

Thanks for some new ideas.

73,

Mark K8MHZ
 
Liquid Metal Antennas  
by KR6EL on March 2, 2006 Mail this to a friend!
What is the DC resistance of this "liquid metal"? 50 ohms is what after AC?
 
RE: Liquid Metal Antennas  
by KA0PMD on March 2, 2006 Mail this to a friend!
I would like to make a fan dipole out of Galinstan.

73,

KAØPMD
Reno, Nevada
 
RE: Liquid Metal Antennas  
by KC0JBJ on March 3, 2006 Mail this to a friend!
"Still not as cool as using a Home Depot motorized tape measure as your own adjustable vertical."

If you are interested in this or have already put one together and can give some advice, please check out the discussion on HF Tape Measure antennas on the Elmer's Forum here on eHam:

http://www.eham.net/forums/Elmers/109671

By the way, did you know there are two (at least) versions of the Black and Decker Autotape (motorized tape measure)? I am going to post the differences on the Forum.

Interesting discussion of non-mercury liquid metal. In high school I played with an alloy called "Wood's Metal". It was solid at room temperature, but would melt in hot water and soften in your hand......Hmmmm, does that present any possibilities......?

 
RE: Liquid Metal Antennas  
by KB1LKR on March 3, 2006 Mail this to a friend!
Wood's metal is approximately 50% bismuth, 25% lead, 12.5% tin and 12.5% cadmium -- so I wouldn't eat it and it's not RoHS compliant due to the Lead & Cadmium, but it would be safer than N3UMH's Sodium (~98°C M.P. if memory serves, or NaK (Sodium-Potassium) alloys, which over a fair range of ratios is liquid at room temperature -- but, like straight sodium, weatherproofing remains CRITICAL!

I think McMaster-Carr ( www.mcmaster.com ) carries Wood's metal and related alloys, as perhaps does Small Parts, Inc. ( www.smallparts.com ). both are a good source of supply for other odds and ends too.
 
Liquid Metal Antennas  
by KD7WAX on March 3, 2006 Mail this to a friend!
I am all for it. I think this will get me above the 5 WPM I could not obtain otherwise. And the cat in the picture seems to approve. So yea to liquid metal antennas.
 
RE: Liquid Metal Antennas  
by WA2JJH on March 4, 2006 Mail this to a friend!
Hey why not. Pushing the envelope of techno;ogy has always been a ham radio thing to do.

The reason why the FCC gave hams so much spectrum above 50mhz, was because back then 440 was considered microwaves.

Back to liquid polymer metals. Hmmmmmm could one not build a glass tube filled with a liquid metal polymer.

How about a free standing UHMW polyethylen filled tube with a murcury composite. One could tune the antenna by using a heating coil.

You want 10M...heat untill the liquid metal rises to 8-9 feet. I guess a free standing (MURCURY THERMONOMTER) COULD BE USED UP TO 20m. I would then use a16 foot solid copper wire as a counter poise.

Have fun. If it works........patent before publish!!!!!
 
RE: Liquid Metal Antennas  
by N1LQJ on March 9, 2006 Mail this to a friend!
intresting, with the right equipment you can run a weather station from one antenna, an antenna and barometer in one. I would imagine a constant feedback loop is necessary, for air pressure and temp. changes, remember you selected a metal design to respond to temp. changes.
 
April’s fools and hardships of invention  
by KD8CIK on March 9, 2006 Mail this to a friend!
A basic understanding of physics and practical dynamics can answer many questions without your having to be an expert. All metals, and most all materials, respond to temperature changes. I guess this is a world filled with “antennas that measure temperature“…

I also mention that a closed system of air or hydraulic fluid could be used to push the liquid metal - eliminating outside air pressure (or feedback & gages can be used). We have been doing similar things in industry for many years. (Much of my practical knowledge comes from working as an industrial mechanic for Guardian Industries, fixing CNC glass cutting machines and other PLC driven equipment. Seeing is believing.)

Where other people see jokes or hardships, the real genius pushes on. Who was the fool who thought that you could produce lasing light buy electrically heating a thin wire? It must have been a waste of time to most people. Another April’s fools joke - and it’s reminder seems to be everywhere.

Michael Lake - KD8CIK
- Also the inventor of the highest gain omni directional antennas the world may ever see, the Parabolic Discone. (It is also on my website HamDomain.com.)
 
RE: April’s fools and hardships of invention  
by WA2JJH on March 11, 2006 Mail this to a friend!
i like the past posters idea of using hydrolics.
Avaition hydrolics prefered!
 
RE: April�s fools and hardships of invention  
by WW2W on May 13, 2006 Mail this to a friend!
All this talk Foolery? Nonsense!
The "shortcomings" of your desired device have led me
into an idea you may also perhaps tinker with: How about a very accurate barometer in which the liquid antenna itself is the oscillating freqency determining element
of a circuit. I also think that in this case one may throw up one's hands and use mercury.
How about using liquid metal for variable caps?
There must be some application where tuning diodes
and HV glass variables don't hack it where this would.
Maybe even a "Liqicap BFO" for fine tuning that SSB BFO those last few hundred hz. Hmmmm. The main problem you will find with all your liquid designs will be microphonics. As you know, liquids are VERY good for picking up vibrations. Just a few thoughts thrown at the wall, good luck. Have fun and watch out for those poisonous metals! 73 de Tony WW2W
 
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