Conical liquid antenna for wide range of frequencies

https://inderscience.blogspot.com/2021/11/developing-liquid-radio-antenna.html

"simple, low cost... can be tuned easily... omnidirectional... transparent... wireless applications... 30 to 40 percent shorter than its equivalent metal antenna... pure water, seawater, and glycerin as the liquid component... voltage standing wave ratio of 1 to 2 over a frequency range of 300 to 850 megahertz... gain achieved in experimental results was 2 dBi... operating frequency is adjusted by changing the height of liquid within the cone"