Reconfiguring the Operating Frequency of a Gallium-Based Liquid Metal Yagi-Uda Antenna by Stretching

This paper presents a reconfigurable Yagi-Uda antenna. The driven element is a loop antenna and the parasitic elements are annular in shape. The antenna can be reconfigured by stretching the elements. In practice, the elements would be formed from silicone tubing filled with Gallium-based liquid metal. The full-wave simulation results show the effect of stretching the diameter of the loop antenna along with the parasitic elements. We can achieve continuous frequency reconfiguration from 1.41 GHz to 0.55 GHz (equivalent to a tuning ratio of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.6: 1$</tex>). Throughout this range, the antenna maintains a return loss of at least 10 dB and a realized gain of over 7 dBi. Finally, we explored a range of other approaches for designing the antenna. We considered the effect of those approaches on the total tuning range and realized gain. The largest frequency tuning range was obtained after setting the element-to-element spacing so that it was correct for every frequency, within the tuning range. With this we were able to achieve continuous frequency reconfiguration from 1.46 GHz to 0.27 GHz (equivalent to a tuning ratio of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5.4: 1$</tex>). Throughout this range the antenna maintains a return loss of at least 10 dB and a realized gain of over 7 dBi, at the operating frequency.