A microwave plasma closing switch and stealth plasma antennas

Summary form only given, as follows. We have developed a microwave closing switch (in contrast to the TR opening switches used in RADAR), that has up to 65 dB difference in transmission open vs closed. The basic concept is a coaxial line in which the center conductor is a glass tube filled with a low-pressure gas, and the outer conductor is a metal pipe. Normally, this structure corresponds to a cylindrical wave guide beyond cutoff and microwave transmission along the structure is negligible. However, when the gas in the cylindrical glass tube is ionized, it behaves as an excellent conductor, and the structure becomes a coaxial line that efficiently transmits microwaves. Applications include modulation as well as microwave switching. We have found that ordinary fluorescent lamps can be used as the central conductor. In another application of the same technology we have constructed antennas out of glass tubes filled with low-pressure gas. When the gas is ionized, we have an efficient, highly-directional receiving or transmitting antenna. When the gas de-ionizes, the structure reverts to a simple structure of glass tubes, with negligible RADAR cross-section.