A new antenna that uses saltwater and plastic has been developed by Lei Xing and her colleagues at the College of Electronic and Information Engineering at Nanjing University of Aeronautics and Astronautics in China

IEEE Spectrum reports researchers have developed an advanced liquid-based antenna system that relies on a readily available ingredient: saltwater.

The saltwater-based antenna that achieves 12 directional beam-steering states and one omnidirectional state. Its circular configuration allows for complete 360-degree beam-steering and works for frequencies between 334 to 488 MHz.

The proposed design consists of a circular ground plane, with 13 transparent acrylic tubes that can be filled with (or emptied of) saltwater on demand. One tube is located in the centre to act as a driven monopole (the radio signal is fed in via a copper disk at the base of the tube).

Surrounding it are 12 so-called parasitic monopoles. When only the driven monopole is excited, this creates an omnidirectional signal. But the 12 remaining monopoles, when filled with water, work together to act as reflectors and give the broadcasted signal direction.

More Information - https://spectrum.ieee.org/tech-talk/telecom/wireless/new-antenna-uses-saltwater-to-achieve-multiple-beamsteering-states