March/April 2010

Radar to map ice formations remotely

The National Aeronautics and Space Administration (NASA) has awarded $2.4 million to the Georgia Institute of Technology to develop a new type of radar system that will be used to study the Earth's ice and snow formations from the air. The system could provide new information about the effects of global climate change.

The research will create a small, lightweight, low-cost phased-array radar that uses silicon-germanium (SiGe) chips in tandem with radio-frequency micro-electromechanical systems. The system being developed could be mounted on aircraft or satellites to enable high-quality mapping of ice and snow formations.

Traditionally, research on frozen areas has required bulky radar equipment that must be operated on the surface, said John Papapolymerou, a professor in Georgia Tech's School of Electrical and Computer Engineering who is principal investigator on the project. The lightweight radar approach could allow unmanned aerial vehicles to gather information by flying over a large area such as Greenland, using the radar system to map ice sheets in three dimensions.

"This aerial approach would greatly facilitate environmental remote sensing of ice, allowing us to map larger areas of interest to better understand location, quantity and composition," said Papapolymerou, who is teamed with another Georgia Tech professor, John Cressler, and Ted Heath, a Georgia Tech Research Institute senior research scientist. "This mapping ability is very important because we need to know about ice accumulation, consistency and stability."

Phased-array radar technology uses fixed, interconnected antenna elements to send and receive multiple radar signals almost simultaneously. This approach employs a technique called phase-shifting to electronically steer the radar-signal beam.

The basic sub-array unit under development consists of a flat grid with eight antenna elements on a side-64 in all. These sub-arrays, measuring about 8.5 by 7 inches, can be combined to create a larger radar array capable of high-quality 3-D mapping.