Optically transparent, radio frequency, planar transmission lines
View Patent ↗A high radio frequency transmission line having a dielectric substrate with two sides and constructed of a transparent material. An electrically conductive strip extends along at least a portion of one side of the substrate. An electrically conductive film is deposited on one of the sides of the substrate at a position spaced from the conductive strip. This conductive film has a thickness sufficiently small so that the film is substantially transparent.
1. A high radio frequency transmission line comprising a transparent structure that comprises:
a dielectric substrate having two sides and constructed of a transparent material;
an electrically conductive strip comprising a highly conductive, optically opaque metallic film having a width of less than a millimeter and a thickness of at least five skin depths of the operating frequency of the transmission line extending along at least a portion of one side of said substrate; and
an electrically conductive film having a thickness of less than one skin depth of an operating frequency of the transmission line deposited on one of said sides of said substrate at a position spaced from said conductive strip, said film having a thickness sufficiently small so that said film is substantially transparent;
wherein said transparent structure provides low power insertion loss of a radio frequency, microwave or millimeter wave signal at frequencies ranging from 5 GHz to 43 GHz;
further wherein said transparent structure provides a minimally obstructed view of a distant object.
2. The transmission line as defined in claim 1 wherein the thickness of said film is less than a skin depth of an operating frequency of the transmission line.
3. The transmission line as defined in claim 2 wherein said thickness of said film is substantially one fifth of the skin depth at said operating frequency of said transmission line.
4. The transmission line as defined in claim 1 wherein said substrate is constructed of sapphire.
5. The transmission line as defined in claim 1 wherein said substrate is constructed of quartz.
6. The transmission line as defined in claim 1 wherein said substrate is constructed of amorphous silicon dioxide.
7. The transmission line as defined in claim 1 wherein said substrate is constructed of a transparent polymer.
8. The transmission line as defined in claim 1 wherein said conductive strip comprises a metal selected from the group consisting of silver, copper, gold and alloys thereof.
9. The transmission line as defined in claim 8 wherein said metal comprises gold.
10. The transmission line as defined in claim 8 wherein said metal comprises silver.
11. The transmission line as defined in claim 8 wherein said metal comprises copper.
12. The transmission line as defined in claim 1 wherein said conductive strip and said film are disposed on opposite sides of said substrate.
13. The transmission line as defined in claim 1 wherein said conductive strip and said film are disposed on the same side of said substrate.
14. The transmission line as defined in claim 1 wherein said film comprises a carbon nano-structured material.
15. The transmission line as defined in claim 14 wherein said carbon nano-structured material comprises carbon nano-tubes.
16. The transmission line as defined in claim 1 wherein said film comprises a transparent conducting oxide.
17. The transmission line as defined in claim 1 wherein said film comprises a transparent conducting polymer.
18. The transmission line as defined in claim 1 wherein said film comprises a grid of conducting nano-wires.
19. The transmission line as defined in claim 1 wherein said film comprises an ultra-thin metallic film having a thickness of not greater than 10 nanometers.
20. The transmission line as defined in claim 1 wherein said film comprises an encapsulated transparent conducting fluid.
21. A high radio frequency transmission line comprising a transparent structure that comprises:
a dielectric substrate having two sides and constructed of an optically transparent material;
an electrically conductive strip comprising a highly conductive, optically opaque metallic film having a width of less than a millimeter and a thickness of at least five skin depths of the operating frequency of the transmission line extending along at least a portion of one side of said substrate; and
an electrically conductive film having a sub-skin depth thickness of the operating frequency of the transmission line wherein said electrically conductive film comprises a substantially transparent carbon nanotube network that is deposited on one of said sides of said substrate at a position spaced from said conductive strip, said film having a thickness sufficiently small so that said film is substantially transparent;
wherein said high radio frequency transmission line provides low power insertion loss of a radio frequency, microwave or millimeter wave signal at frequencies ranging from 5 GHz to 43 GHz;
further wherein said transparent structure provides a minimally obstructed view of a distant object.
22. The transmission line as defined in claim 21 wherein the thickness of said electrically conductive film is less than one skin depth of an operating frequency of the transmission line.
23. The transmission line as defined in claim 21 wherein said thickness of said film is substantially one fifth of the skin depth at said operating frequency of said transmission line.
24. The transmission line as defined in claim 21 wherein said conductive strip comprises a metal selected from the group consisting of silver, copper, gold and alloys thereof.
25. The transmission line as defined in claim 21 wherein said substrate is constructed of an optically transparent material selected from the group consisting of sapphire, quartz, amorphous silicon dioxide, glass, and transparent plastics.