Manuscript received July 17;
1995. This work was supported in part by the U.S. Army Research Office through grant DAAL03-89-G-0030. H.-s. Hwang;
T;
W;
Nuteson;
M;
B;
Steer;
and J. W. Mink are with the Electronics Research Laboratory;
Department of Electrical and Computer Engineering;
North Carolina State University;
Raleigh;
NC 27695-7911 USA. J. Harvey is with the U.S. Army Research Office;
Research Triangle Park;
NC 27709-2211 USA. A. Paollela is with the Microwave and Lightwave Components Division;
AMSRL-EP-MA;
U.S. Army Research Laboratory;
NJ 07703 USA. Publisher Item Identifier S 1051-8207(96)00910-1;