The Design and Manufacturing Process of an Electrolyte-Free Liquid Metal Frequency-Reconfigurable Antenna

Abstract

This communication provides an integrated process route of smelting gallium-based liquid metal (GBLM) in a high vacuum, and injecting GBLM into the antenna channel in high-pressure protective gas, which avoids the oxidation of GBLM during smelting and filling. Then, a frequency-reconfigurable antenna, utilizing the thermal expansion characteristic of GBLM, is proposed. To drive GBLM into an air-proof space, the thermal expansion characteristics of GBLM are required. The dimensions of the radiating element of the liquid metal antenna can be adjusted at different temperatures, resulting in the reconfigurability of the operating frequency. To validate the proposed concept, an L-band antenna prototype was fabricated and measured. Experimental results demonstrate that the GBLM in the antenna was well filled, and the GBLM was not oxidized. Due to the GBLM being in an air-proof channel, the designed liquid metal antenna without electrolytes could be used in an air environment for a long time. The antenna is able to achieve an effective bandwidth of over 1.25–2.00 GHz between 25 °C and 100 °C. The maximum radiation efficiency and gain in the tunable range are 94% and 2.9 dBi, respectively. The designed antenna also provides a new approach to the fabrication of a temperature sensor that detects temperature in some situations that are challenging for conventional temperature sensing technology.

Application of Machine Learning in Electromagnetics: Mini-Review

“…Reconfigurability in antenna can be achieved through different mechanisms such as electrical, optical, physical, and/or material changes [97][98][99][100][101]. ML has become popular with reconfigurable antennas, specifically frequency-reconfigurable ones [102,103].…”

A Gravity-Triggered Liquid Metal Patch Antenna with Reconfigurable Frequency

“…The existing techniques of deforming and reconstructing liquid metal can be divided into mechanical and electric actuating methods. Mechanical actuating includes, e.g., methods such as pressurization by a syringe [ 11 , 12 , 13 , 14 ] or a pump [ 15 , 16 , 17 ], thermal expansion [ 18 ], gravity [ 19 , 20 ], or external forces [ 21 , 22 , 23 ]. Instances of electric actuating include electrochemistry [ 24 , 25 ] and capillary electrowetting [ 26 , 27 ].…”

“…There are advantages and disadvantages in those driving modes of the liquid metal. External forces [ 18 , 19 , 20 ] or syringe injection [ 9 , 10 , 11 , 12 ] methods may not be convenient enough. Pumping methods [ 13 , 14 , 15 ] often require specially designed auxiliary flow channels.…”

“…The melting points of gallium and common bismuth-based alloys are higher than room temperature (25 °C), so elemental gallium and bismuth-based alloys are not suitable for applications that need to remain in a liquid state at room temperature. Therefore, in this work, EGaIn (a kind of gallium-based alloy, with a melting point of 15.5 °C [ 18 ]) was selected from many types of liquid metals. However, compared with mercury, EGaIn is more prone to oxidation [ 17 ].…”

A Compact Octa-Band Frequency Reconfigurable Antenna for Wireless Applications

“…In the last decade, reconfigurable antenna gains considerable attention of researchers due to an exponential increase in the number of users connected to the internet [1,2]. Reconfigurable antennas provide the ability to switch polarization, frequency, and pattern as per user's demand [3][4][5][6].…”