Highly Transparent and Tunable Antenna Window Using Saltwater for UHF Band Applications

Abstract

This paper presents a highly optical transparent and tunable liquid antenna for applications on the UHF band. The antenna has high transparency (> 91%), which is achieved through its use of salty water as a conductive medium held within a clear and hollow acrylic rectangular prism, allowing its use as an optical window. To achieve frequency- and beam-tunable characteristics, two advanced configurations of the antenna using dual-port feeding are proposed. The antenna’s performance is simulated and then verified through experiments. Measurement results show that for a basic configuration using single-port feeding, the antenna has a −6 dB bandwidth ranging from 350 to 675 MHz and efficient radiation efficiency (> 60%) over the band. For advanced configurations, a tunable frequency and directional radiation pattern can be achieved with enhancing gain compared to the basic configuration. These results demonstrate the proposed antenna can be used as a bi-functional device, i.e., as atunable antenna and optical window.