Practical issues

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5. Liquid metal Elastic Stretchable wire - 6. Practical issues

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Resistance of Liquid Metals and other metals

Before you worry that the resistance of liquid metals is too high, consider the applications and the overall effect.  For example, if I am only using liquid metal to "tune" the end of an element then the effect on the overall resistance is less.  There are other advantages, like being able to tune to reduce SWR loss.

The following table is a comparison of different metals.  I converted this information from various sources and verified it, so I believe it is generally correct.  If you see any errors, let me know.

Ohms mm2/m gives you a good idea of the resistance for 3 feet of a liquid metal in the 1/16 inch id tubing that I am using.  It is interesting that liquid Mercury has about twice the resistance of Galinstan liquid metal.  The metals that make up the Galinstan each have less resistance than the alloy, so I wonder if a better compromise of resistance vs. melting point could be made.  It might not hurt it to freeze in certain applications.
 
Metal
Ohms mm2/m Times better
than Galinstan
Times worse
than Copper
Melting
Point °F
Galinstan liquid metal
(Gallium, Indium, Tin)
0.435 1 25.8 -4
Mercury liquid 0.961 0.452 57.2 -38
Gallium 0.147 2.59 8.75 86
Indium 0.0861 5.05 5.12 314
Tin 0.109 3.99 6.48 449
Lead 0.208 2.09 12.3 621
Steel 0.450 0.97 26.7 2750+
Brass 0.035 12.4 2.08 1500+
Aluminum * 0.0265 16.4 1.58 1220
Copper 0.0168 25.8 1 1982

* Caution:  Gallium based liquid metals will dissolve quickly into aluminum, and can ruin the aluminum.  Interestingly a very small amount can be used to "weld" two pieces of aluminum together.
 

Links & more

Liquid Metal Antenna group on Yahoo!

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