1. a U.S. Army Research Office , P.O. Box 12211, Research Triangle Park, North Carolina, 27709, U.S.A
2. b Department of Electrical and Computer Engineering , North Carolina State University , Raleigh, North Carolina, 27695, U.S.A
3. c U.S. Army Electronics Technology and Devices Laboratory , Ft Monmouth, New Jersey, 07703, U.S.A
4. d Scientific Research Associates , Inc.,50 Nye Road, Glastonbury, Connecticut, 06033, U.S.A