How phased array antennas can meet the growing demands of wireless systems
Martijn de Kok defended his PhD thesis with the distinction cum laude at the Department of Electrical Engineering on November 25th.
Wireless communication and radar technologies are evolving at a remarkable pace. From the explosion of commercial satellites to the radars that keep cars and airspace safe, these systems must deliver higher performance while becoming smaller, more efficient, and more power-conscious. Within his PhD research Martijn de Kok explored how active phased array antennas鈥攂uilt from many small antennas working together鈥攃an meet those rising demands through smart design, tight integration, and scalable architectures. His work shows how bringing antennas and electronics closer together, rethinking conventional design rules, and leveraging advanced packaging technologies can significantly enhance the next generation of radar and wireless systems.
The research of Martijn de Kok begins with a large, flat phased array concept for a large-scale naval radar. By using electronics common in mobile networks, the design keeps costs practical while achieving high power and precise long-range performance. A key innovation is the reduced number of active elements near the array edges, combined with integrated cooling channels to maintain efficiency. A small-scale demonstrator was built and tested, confirming the potential of this architecture for powerful, fast-steering radar systems.
When antennas and electronics become one system
The second part dives into how antennas and the connected electronics can be designed together. Traditionally, antennas and the connected electronics are designed separately. This thesis demonstrates that by integrating them close together, considering their interactions, and letting go of conventional design methods, their overall performance can be improved. A new simulation model was created to capture these interactions and guide a more holistic design process. To prove this unconventional co-design approach, a fully custom 16-element array was designed, realized, and measured鈥攄emonstrating clear performance benefits over conventional design workflows.
Millimeter-wave integration for the radars of tomorrow
The final part of the research dives into the millimeter-wave frequencies, where the antenna sizes can be sufficiently small to integrate them on the same chip or in the same package as the electronics. This opens the door to compact, highly efficient solutions for applications such as automotive radar. The research reveals that package-level integration outperforms traditional on-chip approaches, offering better efficiency and performance. A prototype antenna was developed in Fraunhofer IZM鈥檚 advanced package technology and measured at 黑料福利网, showcasing the practical benefits of this high-level integration.
Toward scalable, efficient, and integrated radar systems
By combining theoretical insights with real demonstrator hardware, this work advances the understanding and development of scalable, high-power, and highly integrated phased array antennas. It demonstrates new design workflows, validates innovative integration strategies, and delivers practical prototypes鈥攆acilitating future wireless and radar technologies that are faster, smaller, and more capable.
Title of PhD thesis: . Supervisors: Dr. Ulf Johannsen and Prof. Bart Smolders and Prof. Stefania Monni.
PhD in the picture
What was the most significant finding from your research, and what aspects turned out to be most important to you?
My research consists of three distinct design topics for high-performance active array antennas: keeping large arrays practically scalable, co-designing the electronics and antennas to optimize their joint performance, and integrating antennas within chip packaging technologies to minimize the system size and losses. Choosing one would do a disservice to the other topics. Most importantly for me, however, is that in all three lines of research I had the chance to design, realize and measure actual antenna systems to demonstrate how the strategies described in my thesis work. This combination of theory and hands-on experience, combined with the many collaborations with external companies and institutes, really made my PhD fall into place for me. Another important factor I have to mention is the joy of teaching and guiding student projects that felt like the cherry on top of the work.
What was your motivation to work on this research project?
My MSc-internship at the NASA Jet Propulsion Laboratory was one of the big motivators for me to go for a PhD, and to proceed with the topic of applied electromagnetics. Then, in my graduation project, I worked on the design of an active antenna array radar system for Thales Nederland. I enjoyed the project, it went well, and I clicked well with my supervisor Ulf who then offered me a PhD-position on radar antennas. And the rest is history!
What was the greatest obstacle that you met on the PhD journey?
You have to define your own little 鈥榳ins.鈥� When I was studying for my BSc and MSc, there is a regular flow of (midterm) exams that you have to prepare for and overcome. As long as that goes well, that results in a pretty regular series of short-term motivational boosts after getting through each exam period that keep you going to the next one. The PhD is not necessarily like that, as the big success-moments that link to clear progression (for instance, a paper gets accepted) are generally much farther apart. There have been weeks working on a project with no clear view of whether it will lead to a workable outcome, and that is where pushing through and not getting distracted by too many side-projects became a big but important challenge.
What did you learn about yourself during your PhD research journey? Did you develop additional new skills over the course of the PhD research?
I think I have gotten better at handling a variety of projects at once, or at least at prioritizing the most important one at any given time. I鈥檓 also much more comfortable in presenting about my work in front of an audience: it really does get better with practice. And most of all I have learned that the people around me, family, friends and colleagues, are what brings the joy to all I do. Even when working alone on my own projects, I need to have people around to motivate, distract, and inspire me to give it my all. Having a coffee break to get out of the office, relax and discuss with others at least once a day is essential to doing science: the coffee is optional.
What are your plans for after your PhD research?
I already started working at the Radar Technology department of TNO, developing my expertise in radar systems and high-power antenna arrays. There are good connections between the electromagnetics-focused groups of TNO and 黑料福利网, and I鈥檇 like to strengthen these connections by keeping in touch with the 黑料福利网 researchers.