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Electronically steerable plasma mirror

Electronic steering of microwave beams using a plasma mirror allows the use of wide instantaneous bandwidth waveforms. Areas of application for a plasma mirror based antenna system include ship self-defense, high-resolution radar imaging, high data rate communications, spread spectrum links, and remote sensing. Recent experiments have demonstrated that a planar plasma mirror immersed in a magnetic field, can be formed with electron densities high enough to reflect X-band microwaves. The plasma sheet can be steered in elevation by tilting the magnetic field, and steering in azimuth may be accomplished by designating cathode initiation sites. The measured radiation pattern for a 90/spl deg/ reflection from a 50 cm/spl times/60 cm plasma mirror is very similar to that obtained from a metal mirror of comparable dimensions. As a reflector, the plasma mirror exhibits extremely low loss, the reflectivity is very nearly 100%, and the sidelobes are down by >20 dB. Switching times between successive mirror orientations may be less than 10 /spl mu/s.