1. D L Jaggard, J C Liu and X Sun,Electron Lett,77, 27 (1991)
2. C M Krowne,IEE Proc. 140, 242 (1993)
3. N Engheta and P Pelet,Opt. Lett. 593, 14 (1989)
4. N A Krall and A K Trivelpiece,Principles of plasma physics (McGraw-Hill Inc., 1973)
5. C M Krowne,IEEE Trans. Antennas and Propag. 24, 12 (1984)