





1. Introduction: I wanted the ideal antenna, one that would work its best on any frequency that I needed. Similar looking to an old fashioned mercury thermometer, I used air pressure to push a column of non-toxic liquid metal to the height I wanted out of a container. Electrical contact in the container turned the column of liquid metal into an adjustable antenna of any length that I desired! The height of the liquid metal is proportional to the air pressure used to push it up, so either an air pressure gauge or automatic system can be used for correct adjustment. You can apply this idea to multiple elements, or use columns of liquid metal to tune the ends of solid antenna designs. Why have a narrow bandwidth beam antenna when you could adjust the length of all the elements at once? Instead of mercury I am using a non-toxic liquid mental alloy called Galinstan. It contains Gallium with other metals and is used in Geratherm thermometers. See their website on the following link:

http://rgmd.com/therm/faq/ I realized that this idea can have significant impacts on the design and use of antennas. What is more interesting is that it could have been done with mercury over 50 years ago! My belief is that our society teaches people to be narrow minded, so major "simple" ideas may still be waiting to be discovered. Regardless of what the world thinks, I have the potential antenna of my dreams.



Apply these ideas to other liquids I only chose liquid metal because it was a better conductor. Salt water could be substituted for example, though it may not be as efficient. See the Ionic Liquid Antenna, or ILA, on N9ZRT's website.



Why not use solid adjustable antennas? I have tried automatic car radio antennas, adjustable springs, and other ideas. If they were reliable and convenient for making adjustable transmitting antennas then I, and many others, would be using them. What happens to the unused parts of an adjustable solid antenna? For example, the retracted sections of an automatic car antenna add capacitance to ground, cause an impedance problem, and provide an unwanted path for RF. There are also multiple contacts in the telescopic antenna that are subject to wear, weather, and high currents if used for transmitting. What about accurate positioning? Would it be practicable to make an adjustable Yagi beam like in the diagram to the right above, using solid adjustable elements? The basic advantage of using liquid metal is that the RF can be kept in a straight line for the best (and predictable) velocity factor, inductance, and impedance. Coils, springs, and solid sliding elements can have problems with RF.



Solid multi-band or wide band antennas? There are advantages with an adjustable antenna for one band at a time, like the liquid metal antenna. It helps reduce out of band harmonics and receiver IMD caused by out of band signals. Multi band antennas are usually not as efficient because of coil and other loss. Wide band antennas like the discone have other issues. Both solid multiband and wideband antennas have additional problems when put into arrays for gain.



On the Air Testing (as of 12-29-05) Over the Christmas weekend I tested my prototype on the 2 meter band (144-148 Mhz). As would be expected, the Liquid Metal Antenna (LM-Antenna) acted like a normal metal antenna of a given length. The SWR could be matched near 1:1 and it took 5 watts with no problem. I tried the local 146.940 TRAC repeater but it did not respond (no one else was using it either). The other 147.375 TRAC repeater did pick up my LM-Antenna but no one appeared to be listening. I did hear myself on the repeater by listening with a separate scanner. So, the first person-to-person contact with my LM-Antenna has yet to be written about.