Plasma radio-frequency waveguide switch
The plasma radio-frequency (RF) waveguide switch utilizes the RF transmission cutoff frequency property of ionized gas (plasma) to implement an RF switch in waveguide. The plasma RF waveguide switch includes a waveguide defining an inner space and having an input port for receiving an RF signal and an output port, a plasma chamber placed in the inner space, ionizable gas contained in the plasma chamber, and at least one activator configured to activate the ionizable gas into a plasma state. The plasma chamber is self-contained and hermetically sealed, and therefore, the plasma RF waveguide switch does not require an external gas tank or gas supply device. The plasma chamber includes a first dielectric hermetic waveguide window at a side of the plasma chamber and a second dielectric hermetic waveguide window at an opposite side of the plasma chamber.
1 . A plasma radio-frequency (RF) waveguide switch, comprising:
a waveguide defining an inner space and having an input port for receiving an RF signal and an output port;
a plasma chamber placed in the inner space, wherein the plasma chamber is self-contained and hermetically sealed, and wherein the plasma chamber comprises a first dielectric hermetic waveguide window at a side of the plasma chamber and a second dielectric hermetic waveguide window at an opposite side of the plasma chamber;
ionizable gas contained in the plasma chamber; and
at least one activator configured to activate the ionizable gas into a plasma state.
2 . The plasma RF waveguide switch of claim 1 wherein the ionizable gas includes argon, xenon, neon, krypton, hydrogen and/or helium.
3 . The plasma RF waveguide switch of claim 1 wherein the first and second dielectric hermetic waveguide windows are λ/2 thick or electrically thin, where λ is a wavelength of the RF signal received in the waveguide.
4 . The plasma RF waveguide switch of claim 1 wherein the activator comprises one or more filaments placed inside the plasma chamber and filament electrodes through hermetic feedthroughs connecting the one or more filaments to a ballast.
5 . The plasma RF waveguide switch of claim 4 wherein the one or more filaments are placed along broad walls of the waveguide near the middle of a width of the plasma chamber, minimizing the parasitic effects on the RF signal since the electric field gradients are minimal at the center of waveguide broad wall.
6 . The plasma RF waveguide switch of claim 1 wherein the activator comprises a capacitor comprising a first electrode layer disposed outside the plasma chamber and a second electrode layer disposed outside the plasma chamber facing the first electrode layer.
7 . The plasma RF waveguide switch of claim 1 wherein the activator comprises an induction coil disposed outside the plasma chamber.
8 . A single pole double throw (SPDT) switch, comprising:
a waveguide defining an inner space and comprising an input section for receiving an RF signal and a first and second output sections that separate from the input section at a waveguide junction of the waveguide;
a first plasma chamber placed in the first output section, wherein the first plasma chamber is self-contained and hermetically sealed, and wherein the first plasma chamber comprises a first dielectric hermetic waveguide window at a side of the first plasma chamber and a second dielectric hermetic waveguide window at an opposite side of the first plasma chamber;
a second plasma chamber placed in the second output section, wherein the second plasma chamber is self-contained and hermetically sealed, and wherein the second plasma chamber comprises a first dielectric hermetic waveguide window at a side of the second plasma chamber and a second dielectric hermetic waveguide window at an opposite side of the second plasma chamber;
ionizable gas contained in the first and second plasma chambers;
a first activator configured to activate the ionizable gas in the first plasma chamber into a plasma state; and
a second activator configured to activate the ionizable gas in the second plasma chamber into a plasma state.
9 . The SPDT switch of claim 8 wherein a distance between the waveguide junction and the first plasma chamber is λ/4, where the λ is a wavelength of the RF signal received in the input section.
10 . The SPDT switch of claim 8 wherein a distance between the waveguide junction and the second plasma chamber is λ/4, where the λ is a wavelength of the RF signal received in the input section.
11 . The SPDT switch of claim 8 wherein the ionizable gas includes argon, xenon, neon, krypton, hydrogen and/or helium.
12 . The SPDT switch of claim 8 wherein the first and second dielectric hermetic waveguide windows of the first plasma chamber are λ/2 thick or electrically thin, and the first and second dielectric hermetic waveguide windows of the second plasma chamber are λ/2 thick or electrically thin, where λ is a wavelength of the RF signal received in the input section.
13 . The SPDT switch of claim 8 wherein the first activator comprises one or more filaments placed inside the first plasma chamber and filament electrodes connecting the one or more filaments to a ballast, and the second activator comprises one or more filaments placed inside the second plasma chamber and filament electrodes connecting the one or more filaments to the ballast.
14 . The SPDT switch of claim 13 wherein the one or more filaments of the first activator are placed along broad walls of the waveguide near the middle of a width of the first plasma chamber, and the one or more filaments of the second activator are placed along broad walls of the waveguide near the middle of a width of the second plasma chamber.
15 . The SPDT switch of claim 8 wherein the first activator comprises a capacitor comprising a first electrode layer disposed outside the first plasma chamber and a second electrode layer disposed outside the first plasma chamber facing the first electrode layer, and the second activator comprises a capacitor comprising a first electrode layer disposed outside the second plasma chamber and a second electrode layer disposed outside the second plasma chamber facing the first electrode layer.
16 . The SPDT switch of claim 8 wherein the first activator comprises an induction coil disposed outside the first plasma chamber, and the second activator comprises an induction coil disposed outside the second plasma chamber.