Back Channel — New Phase Shifter Using Liquid Gallium Alloy Yields Impressive Results, Smaller Smartphones?, Exploring The Dark Ages Of The Universe, And More

By John Oncea, Editor

Back Channel presents the most captivating news and innovations in RF and microwaves. This week, we look at a world-record coherent transmission, how RF testing needs to change, a new composite safer than SPE, and more.

A new phase shifter using a liquid gallium alloy shows low signal losses and extremely low phase deviation over a wide bandwidth. Researchers led by Dr. Yi Wang from the University of Birmingham’s School of Engineering say 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 loss of signal (insertion losses) and relatively poor power handling capability. “The new phase shifter does not need cleanroom facilities for fabrication, so is inexpensive to manufacture,” said Wang. “The liquid-metal enabled phase shifting elements have a ‘passive’ nature, unlike the ‘active’ semiconductor-based counterparts, which potentially offers high power-handling capability. Apart from the signature application in phased array antennas, the phase shifters may find a wide range of usages from communications and radars to instruments.”

McGill University (go Redbirds!) and Keysight Technologies have successfully demonstrated a world record 1.2 Tbps and 1.6 Tbps O-band coherent transmissions operating over 10 km using distributed feedback lasers (DFBs) for both the carrier and local oscillator. To address growing short-reach intra-data center traffic demands -- from 2 to 10 km – coherent transmission systems are being considered as an alternative to intensity modulation direct detection (IMDD) systems that are currently operating at 200 Gbps per wavelength over 2 km in the O-band. Low chromatic dispersion makes power-efficient coherent links an attractive replacement for IMDD technologies at 1.6 Tbps and beyond.

A new kind of transistor could shrink communications devices on smartphones, according to the University of Michigan (go Wolverines!) “By realizing this new type of transistor, it opens up the possibility for integrating multifunctional devices, such as reconfigurable transistors, filters, and resonators, on the same platform — all while operating at very high frequency and high power,” said Zetian Mi, U-M professor of electrical and computer engineering who led the research, “That’s a game changer for many applications.”

“When you can continuously test network software, how does RF testing also need to change?,” asks RCR Wireless News. Their answer is an IT tool: continuous integration and continuous delivery/deployment (CI/CD). “CI/CD is all about automating all the test suites – which is easy when what you’re testing is virtual,” says David Woodcock, who handles product strategy for test orchestration company ACentury. “But the radio layer is very much physical.” That often means manual test set-up in a lab that mirrors, as much as possible, the production network. “You can’t do continuous integration and continuous deployment, with continuous testing in the middle, if you have to stop doing what you’re doing and re-align your lab to do the next test,” Woodcock says. “RF is different. I’ve seen it many times in my career where people from the wired IT industry assume that the radio link part of any network is just like an Ethernet cable, and it’s not. So, you need to incorporate that layer into your end-to-end test – and right now, it’s the limiting factor for how fast you can test.”

Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory are leading a new effort to land a radio telescope on the moon. If successful, the project will mark the first step toward exploring the Dark Ages of the universe, an early era of cosmological history starting about 380,000 years after the Big Bang. “Modeling the universe is easier before stars have formed. We can calculate almost everything exactly,” said Brookhaven physicist Anže Slosar. “So far, we can only make predictions about earlier stages of the universe using a benchmark called the cosmic microwave background. The Dark Ages Signal would provide a new benchmark. And if predictions based on each benchmark don’t match, that means we’ve discovered new physics.”

Researchers are attempting to improve the detection of high dynamic range and large field-of-view radio sources, according to Phys.org. Dr. Shan Hao from the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences and his collaborators carried out a preliminary study on the high dynamic range (HDR) radio source detection algorithm based on the full set alternative data release 1 of TIFR GMRT Sky Survey (TGSS). The researchers proposed an angular resolution and discrimination algorithm based on the HDR compression tone-mapping and gain control, which was embedded in the wavelet multi-scale framework. “Our proposed algorithm has certain advantages. It avoids unexpected changes and loss of integrated flux density information in the traditional methods, as well as excessive and false high dynamic information,” said Dr. Shan.

Purdue University (#BoilerUp) announced that a team led by Vilas Pol, a Purdue professor in the Davidson School of Chemical Engineering, has developed a new composite material that is safer to use in solid-state lithium-ion batteries than traditional solid polymer electrolyte, or SPE, technologies. The new battery exhibits stability to cell damage, leading to a huge increase in safety. Pol said traditional SPE materials have other drawbacks. “They have poor thermal stability, which can cause battery thermal runaway and lead to catastrophic firing. Their ionic conductivity is limited to low temperatures, which can reduce energy efficiency and lifetime. And low-energy-density batteries can cause quick energy depletion and short operating times of devices, considering the limited space for a battery in electronics or electric vehicles.”

Finally, our friends at the Association of Old Crows are celebrating women’s history month (hi, mom!) with a podcast that honors the contributions of three women whose discoveries, inventions, and insights made a lasting impact on electromagnetic spectrum operations and, in some cases, helped turn the tides of war: Florence Violet McKenzie, Joan Curran, and Hedy LaMarr. The episode features guest narrator Ms. Shelley Frost, the first woman Executive Director of the Association of Old Crows and let me tell you, the Hedy LaMarr segment was super interesting.