Test capacity bottleneck
As a rule, today’s antennas are tested in so-called anechoic chambers. This is a room where the walls absorb all the echoes, Hübrexen explains. However, both setup and interpretation of measurement data are time-consuming tasks and require a lot of expertise.
“Many companies spend more than a third of their development time testing antenna performance,” she emphasizes. “5G applications are proliferating and every device requires testing. There is a serious bottleneck in terms of testing capacity.”
Recognizing that a completely new approach was needed, Hübrexen started working with TU/e’s Integrated Antenna Systems Group and investigated switching to a different type of measurement chamber. Initially, she and her colleagues were viewed with some suspicion. After all, their vision was novel. In an anechoic chamber, everything is absorbed, but in her “reverberation chamber”, Hübrexen uses metal walls to do just the opposite, reflecting all the waves.
“The concept of reverberation chambers is in acoustics and is not entirely new. We worked with electromagnetic waves instead of sound waves and applied existing low-frequency concepts to high frequencies. So that we could simulate reality by reflection. “Additionally, this significantly reduces the time required to capture all the power radiated by the antenna. Traditional measurement systems require the room to be illuminated before finally compiling everything. Everything is measured in the reverberation chamber.”It also determines whether the device is radiating at the correct frequency and the maximum transmit power, which is an important issue for things like mobile phones.” It also allows for an easy way to measure whether it has been exceeded. It is much more accurate, scalable, and up to 100 times faster when it comes to testing certain aspects of antenna quality. ”
open mind
In order to specifically measure the performance of the high-frequency antenna, a prototype reverberation chamber was built, after which Hübrexen carried out an extensive validation process. Under duress, she admits that this was her pioneering work.
“When I started my PhD project, I was working in the first reverberation chamber capable of handling such high frequencies. I had observed so many aspects of this chamber and with all the measurement work I had done, We were able to eradicate many problems. Gradually, we discovered ways to solve them. We adopted an open-minded approach and were less tied down to stochastic processes where models were used blindly. By ensuring that this was not the case, we were able to translate our findings into a real product.”
practical guide
Although Hübrexen’s research results show that reverberation chambers offer many advantages over current measurement techniques, she still encounters researchers who are skeptical. She believes this is because it is harder to orient the antenna in a reverberant chamber than in an anechoic chamber. This problem is considered to be a serious problem if the direction is significantly related to the high frequency antenna. Radio frequency antennas collect radiation and produce strong signals. .
However, Hubrexen demonstrated that for many measurements, antenna orientation is not as important as expected. For the important measurements, she and her colleagues developed a new methodology for use in reverberation chambers. To help people understand the value of reverberation chambers in measuring the properties of modern antenna systems (antennas and electronics), she presents her work in the form of a practical handbook that shares details of her new approach. I decided to write my doctoral thesis. “How a reverberation chamber works is even more difficult to understand. If it works intuitively, it’s easy to trust. You just have to prove it. That’s it. Because people convinced me to experience for myself how well it works.”
not automatic
She’s seeing this more and more among users, including in her role as CEO of ANTENNEX, a spin-off from TU/e. ANTENNEX was the first company to sell portable high frequency reverberation chambers for commercial use. Her path to a PhD, she reluctantly admits, is far from traditional. Last year, she was asked by the University’s Integrated Antenna Systems Group to become her CEO of the company ANTENNEX, which she founded in 2021.
The company is increasingly receiving requests from large companies to test antenna performance. Similarly, Ms. Hubrexen has been providing measurement services since her undergraduate internship. “After spending a year as a PhD candidate, I decided to leave the project due to work commitments and started a new PhD study in the electromagnetism group. From a timing perspective, it took 18 months. It wasn’t easy to later become the CEO of a startup. It’s a very hands-on move,” she laughs.
After a short silence, she continued in a serious tone. “I had to fight hard to get everything done on time while running a company, but it certainly took its toll. And I was lucky. Good students, lots of students. “The people who supported and helped me, and now a new team and investors, are eager to take ANTENNEX in a new direction. Although this was a great challenge, I would not recommend anyone to spend evenings and weekends competing to complete a dissertation. ”
Source: Cursor.
