Metamaterials Boost Microwave Feed-Horn Performance
Penn State and Lockheed Martin engineers have developed a metamaterials lined feed horn antenna that has low loss, low weight and more than an octave of bandwidth. Potential applications include satellite feeds antennas covering both Ku- and Ka-bands and C-band horns covering both uplink and downlink frequencies. While these horns could be used for Earth-based antennas, the most promising use is for space-based antennas where its wide bandwidth and light weight should easily offset the extra cost for the metamaterial lining.
""Existing horn antennas have adequate performance, but have undergone little change over several decades except for advances in more accurate modeling techniques," said Erik Lier, technical fellow, Lockheed Martin Space Systems. "Modifications enabled by metamaterials can either enhance performance, or they can lower the mass and thus lower the cost of putting the antenna in space."
Douglas Werner, professor of electrical engineering at Penn State, said this is one of the first practical implementations of electromagnetic metamaterials that makes a real world device better.
The researchers--also including Qi Wu and Jeremy A. Bossard, postdoctoral fellows in electrical engineering, and Clinton P. Scarborough, graduate student, electrical engineering, all from Penn State--designed horn antenna liners from metamaterials with special low-index electromagnetic properties, with an effective refractive index between zero and one, and which do not physically exist in natural materials. To increase bandwidth and decrease loss, the antenna liners needed to have repetitive structure considerably smaller than the wavelengths the antenna is designed to transmit.
Ku-band antennas spanning 12 to 18 GHz can be easily fabricated using conventional printed circuit board manufacturing techniques. Super extended C-band antennas require larger structural intervals, about one-quarter inch between wires, to cover 3.4 to 6.725 GHz and can be manufactured as a simple wire grid structure.
A rendering of the antenna
shows the grid structure.