Dynamic Reconfigurable MIMO Antenna Based on Tunable Liquid Metal

Abstract This paper presents a multiple-input–multiple-output (MIMO) antenna that is tuned using liquid metal with electrochemical method. This antenna comprises: two printed Inverted-F antenna (PIFA) elements for radiating and a stretched split ring resonator (SSRR) decoupling structure between elements for keeping mutual coupling at a minimum level. A strip of liquid metal in a fluidic channel which connects to the arm of the two PIFAs, can be used to alter its resonant frequency. A fabricated prototype demonstrates this design in which liquid metal forms the radiating element. Adjusting the physical dimensions of the liquid metal causes the antenna's operating frequency to span a wide bandwidth, ranging from 1.1 GHz to 2.6 GHz. Electromagnetic simulations of the device align closely with empirical measurements of gain and radiation patterns. The device exhibits varying levels of radiation efficiency throughout its tuning range, fluctuating between 87% and 89%. MIMO characteristics such as an envelope correlation coefficient (ECC) less than 0.15 and diversity gain (DG) is approximately 10 dB were measured for two cases of liquid metal.