An UHF Reconfigurable Liquid-Metal Monopole Antenna Based on a 2-D Surface

This article demonstrates an ultrahigh frequency (UHF) liquid-metal monopole antenna qualified for reconfiguring its resonant frequency by stretching or shortening its length on a 2-D surface. The proposed antenna consists of liquid eutectic gallium and indium (EGaIn) and NaOH solution. A power supply generates a direct current (DC) potential between the EGaIn and NaOH solution. Depending on the electrically-driven method to push or withdraw the EGaIn, the antenna is capable of forming different lengths to redistribute the current of the radiating element. Compared with the microchannel liquid-metal antenna, the proposed antenna can be tuned on a 2-D surface, rather than relying on the microchannel for shaping. By varying the length of EGaIn on a 2-D surface, the proposed antenna can provide continuously tunable frequency range and repeatability. For EGaIn monopole antenna with lengths from 50 to 10 mm, the measured resonant frequency operates from 0.78 to 2.42 GHz for a tuning ratio 3.1:1. The application of the design, operation of tuning liquid-metal antenna at several frequencies, and measurement process are explained in this article.