Pneumatically‐Actuated Liquid Metal‐Based Frequency Reconfigurable Antenna

Abstract Software‐defined radios and cognitive radios can switch their operating frequency across a wide range. Although analog and digital circuits enable cross‐frequency operation of much of the RF frontend, there is a lack of practical antennas that are frequency‐reconfigurable over such a wide range. Prior rigid antennas are either narrow‐band with high radiation efficiency, or wide‐band with low radiation efficiency. This study presents a soft, stretchable, compact, omnidirectional liquid metal composite antenna system to enable high radiation efficiency when reconfiguring to different frequencies across a wide band. On the hardware front, an extendable multi‐branch stretchable liquid metal based antenna geometry is optimized that preserves high efficiency when switching across a wide range of frequencies. On the software front, a control algorithm is incorporated that ensures that the antenna automatically configures to the optimal received signal strength. The antenna design enables a strain limit of 33% for two independent actuatable branches, further enabling a switchable operating frequency range across 1–5 GHz. Experimental characterization demonstrates that PASTA reduces the radiation loss by 10–20 dB over the operating frequency range compared to state‐of‐the‐art rigid and flexible antennas.