Making big waves with small waves

Posted on August 11, 2023

Tinus Stander, a professor in the Department of Electrical, Electronic and Computer Engineering in the University of Pretoria’s Faculty of Engineering, Built Environment and Information Technology, delivered his inaugural address on 7 August 2023. The topic of his presentation was “Making big waves with small waves: Today’s challenges in microwave and millimetre (mm)-wave engineering”.

Prof Stander is associated with the Department’s Carl and Emily Fuchs Institute for Microelectronics (CEFIM). He is involved in cutting-edge research in the field of microwave and mm-wave microelectronics, with its transdisciplinary applications, including radio astronomy and transportation.

According to Prof Stander, systems that operate in the microwave and mm-wave frequency range have applications that span the breadth of human endeavours. They are used to connect, see, navigate, heal and understand our universe. The breadth of these applications is matched only by the breadth of challenges facing the microwave engineer to develop better, smarter, smaller, cheaper, greener and more impactful solutions to these challenges.

He introduced the audience to the concepts involved in communication through radio-frequency waves, specifically those related to frequency and bandwidth. He explained that the key trend is to strive for higher frequencies and wider bandwidths to accomplish faster communication and better imaging, particularly in the fields of terrestrial communications, radio astronomy and radar.

During his address, he reflected on a few key challenges across these application domains, and the key research inquiries that contribute to addressing them. He highlighted some of the problems of wide bandwidth signal processing and packaging for 5G and mm-wave communications, and explained how new modelling and frequency filtering approaches can alleviate some of these shortcomings.

He discussed how on-chip filtering and signal routing can be used to improve integrated circuit operation at higher frequencies and higher bandwidth. This is done by integrating as much of the microwave and mm-wave system on a single integrated circuit as possible.

“However, radio astronomy presents a wide range of challenges,” he explained, “not least of which is the need for continuous site monitoring, where low-cost water vapour radiometry has found application”. He explained how water vapour radiometry can be used to estimate the delay and attenuation of radio waves in radio astronomy. His research team has made great strides in developing cheap, low-cost, compact integrated water vapour radiometers.

Outlining some of the challenges faced by a nascent consumer access terminal industry in satellite communications, he described how some challenges can be addressed by using additive manufacturing or 3D printing to produce microwave components. “Additive manufacturing is a valuable technology that can be used as a rapid customisation tool for small-scale production, especially for complex designs,” he explained. This is not only cost effective, but allows one to go through faster iterations of prototyping, which allows one to develop new technologies much sooner. However, there are challenges in using 3D printing in the production of microwave and mm-wave components, especially with regard to the metallisation of smooth, porous 3D printed parts with non-toxic processes. “Resolving these challenges formed an important part of our research.”

Prof Stander then went on to discuss the role and unique difficulties of microwave and mm-wave systems in space. An important element in this regard is the reliability of the technology. “Our development of new approaches to built-in self-testing have made an important contribution to solving challenges related to the use of this technology for improved performance,” he explained.

He concluded his address with an overview of future research his research team plans to conduct to address continuing challenges. “Ongoing research in key areas can help equip the next generation of microwave engineers to face new challenges that arise in the field of microwave and mm-wave microelectronics.”

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