While tall, bulky antennas seem like relics in an era of sleek smartphones, they’re still an unfortunate necessity for American soldiers. “One of the problems that many military communications systems have is that they use low frequencies—anywhere from 2 MHz to below 1 GHz,” says Electrical and Computer Engineering Assistant Professor Nader Behdad. “As a result, very often you see huge antennas sticking off of their vehicles.” Behdad thinks those enormous antennas could be scrapped for low-profile, broadband antennas—thanks to a different approach to antenna design that replaces large dipole antennas with a more compact multi-mode radiator.
With a three-year, $510,000 grant through its young investigator program, the U.S. Office of Naval Research will enable Behdad to develop the next generation of vehicle antennas. He aims to tune multiple parts of the same antenna structure to radiate at different frequencies, using synthetic “metamaterials” to shape their radiation patterns so that they won’t interfere with one another. Made up of metals, dielectrics and other materials, metamaterials react to electromagnetic waves differently based on their index of refraction, making it possible to manipulate two competing radiation patterns to make them work in tandem within a single antenna. Behdad estimates that a 20-by-20-by-3-centimeter antenna could operate anywhere between 200 MHz and 40G Hz and could be flush with a vehicle surface.
Commercially, his research is relevant in areas such as mobile phones and wireless data connections for personal computers. However, the military implications are even more crucial than preparing for a more connected future: Eliminating large antennas from communications equipment could make U.S. soldiers safer. “If you have something like a huge antenna sticking out of a soldier, it paints a pretty big target on them as they walk in the street,” says Behdad.
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