For those interested in antenna design, one of the more recent innovation has been dynamically tunable antennas. This trend started out with screwdriver antennas (where a screen mechanism is used to adjust the antenna length) then a few years ago a hydraulic approach was used to dynamically change the structure of Yagi beams…
Now, North Carolina State University (NCSU) researchers have released a paper titled A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity describing “a new electrochemical method for reversible, pump-free control of liquid eutectic gallium and indium (EGaIn) in a capillary.”
Flashbacks to the 2nd terminator movie anyone?
There was a good IEEE article about this antenna research, but to summarize: by placing a positive or negative voltage across the interface between the liquid metal and an electrolyte, the researchers found that they could cause the liquid metal flow into a capillary changing its operating frequency and radiation pattern.
“Using a liquid metal — such as eutectic gallium and indium — that can change its shape allows us to modify antenna properties [such as frequency] more dramatically than is possible with a fixed conductor,” explained Jacob Adams, an assistant professor in the Department of Electrical and Computer Engineering at NCSU.
It looks like some amateur radio operators have been experimenting with liquid metal antennas for a while.