High-performance antenna switches
Given their high potential, NEM switches are attractive building blocks for next-generation cognitive wireless communication systems. However, fabrication challenges associated with sub-micron lithography systems and processing equipment have prevented their widespread use. In the EU-funded project 'Development of high-performance and high-reliability NEMS switches for smart antenna structures' (NEMSMART), scientists found a way to improve the reliability of NEM switching performance. Research was geared towards two alternative radiofrequency switch technologies. These included microfluidic switches based on liquid metals and switches based on smart materials. Based on the wetting-on-dielectric method, the microfluidic approach had limited success, with liquid-metal droplets undergoing oxidation and leaving metallic residues. As such, scientists investigated the use of smart materials as switching components, which did not involve stiction or contamination. These included ferroelectric and phase-change materials. Although the former exhibited a tuneable dielectric coefficient, the latter showed resistance tenability due to the amorphous-to-crystalline material state transition. The NEM switch ON-OFF ratio was much smaller compared to its micro-electromechanical and microfluidic system counterparts; however, this switching scheme did not involve any fragile parts. Once successfully developed, the proposed high-reliability NEM switches based on smart materials could be easily integrated into antenna architectures to realise multifunctional reconfigurable antennas. NEMSMART thus paved the way for major breakthroughs in antenna design and implementation since the invention of legacy antennas.
Keywords
Antenna switches, nano-electromechanical, wireless communications, reconfigurable antennas, smart antenna structures, radiofrequency switch, microfluidic, liquid metals, smart materials, antenna architectures, antenna design
