ECE PhD student Duncan Madden recognized for his work on antenna arrays

Duncan Madden, a doctoral student in Electrical and Computer Engineering, took 2nd prize in the 2024 Ernest K. Smith USNC-URSI student paper competition for the paper, “In-Situ Calibration of Active Electronically Scanned Antenna Arrays Through SAR Imaging.” His research aims to enable antenna arrays to self-calibrate, reducing the need for human intervention. This is particularly relevant for antenna arrays that are mounted on aircraft or spacecraft. 

“Development of self-calibration methods for antenna arrays would extend the lifetime of arrays deployed for current and future scientific, commercial, or military missions,” said Madden. “It would also reduce maintenance costs and decrease system downtime. Independent calibration is an important step towards automation of the air and space vehicles on which the arrays are deployed.”

Antenna arrays work by adjusting the phase and magnitude of the signal at each antenna element so that the signals constructively or destructively interfere with each other in advantageous ways, explained Madden. If there is some error in how the signals are aligned, system performance can degrade. Calibration is the process of detecting and correcting those errors.

“We addressed the problem by proposing to use backscattered radio frequency signals from the ground below the airborne vehicle as the calibration channel,” explained Madden. “Synthetic aperture radar (SAR) is needed to turn those signals into something usable. From the signals (with SAR), we can form pixelated images, and each pixel can be used as a calibration target. Our experiments so far have shown that this method can be used to accurately determine the channel imbalances between two antennas.”

“The research is an important step for in situ automated calibration and proper operation of airborne and spaceborne active electronically steerable arrays (AESA) for radar and communication systems,” said Kamal Sarabandi, the Fawwaz T. Ulaby  Distinguished University Professor.

Madden has developed a testbed antenna array for further experimentation, which will include testing on a larger scale. “This is a challenging problem which still needs attention and creative solutions,” he said. 

The project requires Madden to explore several different topics in the area of applied electromagnetics, including antenna, transmitter, and receiver hardware design, synthetic aperture radar, and scattering – all of which he is enjoying.

Madden received his bachelor’s degree from the University of New Mexico (UNM), and master’s degree from the University of Michigan. He is the recipient of a National Defense Science and Engineering Graduate Fellowship, and former President of UNM’s student chapter of IEEE-HKN, the national honors society for electrical and computer engineers.

The paper, co-authored by his advisor, Prof. Kamal Sarabandi, was presented at the 2024 National Radio Science Meeting.