A New Type Of Slot Antenna For NextG Communications

The antenna, designed by doctoral student Aditya Varma Muppala and Prof. Kamal Sarabandi, is featured by IEEE Transactions on Antennas and Propagation.

5G has brought the world ultra-low latency, high speed, high reliability, and high capacity for a multitude of highly anticipated applications. Even before 5G was rolled out in 2019, researchers in Electrical and Computer Engineering were working on the next generation of wireless technologies, now called simply NextG.

A critical component of any of these NextG technologies is the antenna used to transmit and receive the information.

Doctoral student Aditya Varma Muppala and his advisor Kamal Sarabandi, the Fawwaz T. Ulaby Distinguished University Professor, have recently published a paper describing a new method for designing a slot antenna for NextG communications.

The paper, “An Ultra-Wideband Quad-Mode SIW Cavity-Backed Slot Antenna for NextG Communication and Sensing Arrays,” is currently featured by IEEE Transactions on Antennas and Propagation.

We talked to first author Aditya Varma Muppala to provide a high-level overview of the technology, and learned about the touch of serendipity that led him to deviate a bit from his core research to develop a new type of antenna, which the authors are calling a Substrate Integrated Waveguide (SIW) Cavity-Backed Slot Antenna.

Can you talk about the research and development of this new type of antenna?
We [Kamal Sarabandi and I] asked ourselves the question, for the next generation of communication systems – called Next G, which is 6G or even 7G, what kind of antenna is needed to make this practical?

We knew it needed to be wideband because we wanted very high data rates. We needed to make it scalable into an array in order to take advantage of phase array based techniques where you can scan a beam in different locations very quickly, and it had to be low profile, low cost, and easy to fabricate.

These are very strict constraints on an antenna. So Kamal and I went back to the drawing board, and we said, ‘Okay, how can we make an antenna that can match all these conditions?’

Kamal had the idea of going back to a paper that he published about 20 years ago, where he introduced a new concept called “fictitious short.”

We combined that with some modern techniques in antenna design, including characteristic mode analysis and coupled mode theory, to show how you can extract the maximum bandwidth from a single slot antenna. The slot antenna, being scalable, satisfies all the other constraints that we had.

So we made a nice antenna. It’s scalable to large arrays, it’s very wide band, it’s low profile, and it’s easy to fabricate.

Slot antennas have been part of my core research. We first implemented this design at 20-30 GHz in a standard way, using a method similar to printed circuit board technology. Then we implemented a similar slot antenna on chip using digital design at 240-270 gigahertz.

So, we’ve shown this concept of fictitious shorts and characteristic mode analysis can extend from the lower end of Ghz to close to THz, both on and off chip. It’s a very versatile design.

What’s the difference in data rates between 5G and 6G?
With 5G, you can get 5-10 gigabits per second. But with 6G, we expect hundreds of gigabits per second.

How does this project fit in with your core research?
My research has focused on antennas for radar, not communications. I was making a wideband antenna for a radar system, and the 10 GHz (40%) of bandwidth I got was way more than what was needed for radar, which came as a surprise. This bandwidth is appropriate for communications, so we developed this technology further along those lines.

Did others contribute to this research, aside from your co-author, Kamal Sarabandi?
I’d like to acknowledge the assistance of Behzad Yektakhah, a postdoctoral researcher with Kamal’s group. He helped me quite a bit with understanding antenna design.

What are your future plans for yourself, and for this research?
I will be defending my thesis soon, and will start at U-C Berkeley this summer as an Assistant Professor. This specific research is not part of my thesis. There is a new student in Kamal’s group that is working on NextG antennas, and she may continue this research.