Triggered-plasma microwave switch and method

A method for selectively directing a microwave signal along first and second signal paths, comprising the steps of:

• providing an ionizable gas of a selected species;
• adjusting the pressure of said gas so that the incidence of a microwave signal will generate from seed electrons in said gas a plasma having a reflecting electron density N.sub.r that is sufficient to reflect said microwave signal from said plasma;
• causing said microwave signal to be incident upon said gas;
• and
• selectively directing ultraviolet light into said gas to direct said microwave signal along a first signal path away from said plasma or omitting said directing of ultraviolet light to direct said microwave signal along a second signal path through said gas.

A method for obtaining a selected phase of a microwave signal, comprising the steps of:

• providing an ionizable gas of a selected species;
• selecting a pressure of said gas so that the incidence of a microwave signal will generate from seed electrons in said gas a plasma having a reflecting electron density N.sub.r that is sufficient to reflect said microwave signal from said plasma;
• dividing said gas into a plurality of gas compartments which are serially connected between an initial gas compartment and a final gas compartment so that said initial gas compartment has a different path length from each of the other said gas compartments;
• causing said microwave signal to be incident upon said initial gas compartment;
• and
• generating seed electrons in a selected one of said gas compartments to reflect said microwave signal along a selected signal path from that gas compartment to said initial gas compartment with a phase which is associated with said selected signal path.

A triggerable microwave switch for selectively directing a microwave signal along first and second signal paths, comprising:

• a microwave transmission member;
• a microwave chamber formed by said transmission member for containing an ionizable gas;
• input and output ports formed by said transmission member to communicate with said microwave chamber;
• and
• an electrode extending into said microwave chamber and arranged to receive a voltage trigger signal to generate a trigger electron density N.sub.t in said gas;
• said microwave signal reflected along a first path from said input port when said trigger electron density N.sub.t is present and directed along a second path to said output port when said trigger electron density N.sub.t is absent.

A triggerable microwave switch for selectively directing a microwave signal along first and second signal paths, comprising:

• a microwave transmission member;
• a microwave chamber formed by said transmission member for containing an ionizable gas;
• input and output ports formed by said transmission member to communicate with said microwave chamber;
• and
• an ultraviolet-radiation generator which is arranged to direct, in response to a trigger signal, ultraviolet radiation into said chamber for photoionization of said gas and consequent generation of a trigger electron density N.sub.t ;
• said microwave signal reflected along a first path from said input port when said trigger electron density N.sub.t is present and directed along a second path to said output port when said trigger electron density N.sub.t is absent.

A tunable short, comprising:

• a plurality of microwave switches, each of said switches having an input port and an output port and configured to selectively reflect a microwave signal from its input port and to transmit said microwave signal from its input port to its output port in response to a trigger signal;
• and
• an entrance port formed by the input port of a first one of said switches with said switches connected in series so that the input ports of the other switches are each spaced by a different path length from said first switch;
• wherein each of said microwave switches includes:
• a) a microwave transmission member;
• b) a microwave chamber formed by said transmission member for containing an ionizable gas and said input and output ports are formed by said transmission member to communicate with said microwave chamber;
• and
• c) a triggered plasma generator configured to generate, in response to said trigger signal, a trigger electron density N.sub.t in said gas;
• so that a microwave signal is reflected along a first path from said input port when said trigger electron density N.sub.t is present and directed along a second path to said output port when said trigger electron density N.sub.t is absent;
• selective application of a trigger signal to different ones of said switches causing a microwave signal received at said entrance port to travel different path lengths as it is reflected back to said entrance port.