Researchers at the University of Birmingham have developed a new type of high-performance ‘phase shifter’ for use in advanced phased array antenna systems. Researchers led by Dr. Yi Wang from Birmingham’s School of Engineering created a new type of high-performance ‘phase shifter’ using a liquid Gallium alloy that varies the phase angle of microwave and millimetre-wave radio signals.
The researchers at the University of Birmingham have developed a new tunable linear phase shifter which boasts a combination of low insertion loss (almost independent of the phase), high phase resolution, and low dispersion. The ‘passive’ phase shifting element also promises capability to handle high power. The phase shifter is based on a new design of substrate integrated waveguide structures, has simple circuitry and is easy to fabricate.
The phase shifter is a key enabling technology for advanced phased array antennas (PAA) which are widely used in mobile base stations, satellites and radar systems. These PAA systems use multiple phase shifters to provide the controlled phase increments that steer the radiation beam. However, current phase shifters typically use semiconductors and suffer from high signal loss (insertion losses) and relatively poor power handling capabilities.
“The new phase shifter does not need cleanroom facilities for fabrication, so it is inexpensive to manufacture. The liquid-metal-enabled phase-shifting elements have a ‘passive’ nature, unlike their ‘active’ semiconductor-based counterparts, which potentially offer high power handling capability. "Apart from their signature application in phased array antennas, the phase shifters may find a wide range of usages, from communications and radars to instruments.” said Dr. Yi Wang, Associate Professor in RF and Microwave Engineering and Head of the Emerging Device Technology Research Lab.
Dr Wang said: “An ideal phase shifter would provide a stable, and wide phase angle range with a minimal loss of signal over the operation bandwidth. However conventional phase shifters suffer from signal losses which increase as the phase angle increases, and the phase varies with frequency. Taken together, these issues can cause signal degradation and impair performance. Rectifying this requires additional complicated circuitry and consumes more power, which adds to both the bulk and the running cost of the entire antenna.”
The research team set out to overcome these long-standing issues by designing a new type of phase shifter that controls the phase shift via a liquid-metal material that runs in microfluidic channels.
The results of prototype testing are published today in IEEE Transactions on Microwave Theory and Techniques and show that, the new phase shifter shows low signal losses that are almost independent of phase angle.
In addition, while most conventional phase shifters provide different phase delays at different frequencies (dispersion), which limits their usable bandwidth and applicability, the new phase shifter has a ‘phase compensation’ technique that provides extremely low phase deviation with frequency over a wide bandwidth.
University of Birmingham Enterprise has filed a patent application covering the microfluidic channel wave-guiding device, and the research team, which has extensive experience of working with industry, is now seeking to licence the novel technology for development and commercialisation and is doing further research to expand this protection.
Click here to learn more about the phase shifter.
