Waveguide, waveguide manufacturing method, and wireless transmission system

1. A waveguide, comprising:

a dielectric including two surfaces, an electric field intersecting with the two surfaces;

metal-plating layers coating the two surfaces of the dielectric, the electric field intersecting with the two surfaces; and

a protective layer coating a periphery of the dielectric including the two surfaces coated with the metal-plating layers, wherein

the protective layer includes a sheet-like conductor wound up around the dielectric including the two surfaces coated with the metal-plating layers.

2. The waveguide according to claim 1 , wherein

the sheet-like conductor is a metal tape.

3. The waveguide according to claim 2 , wherein

the metal-plating layers and the metal tape are made of the same metal material.

4. The waveguide according to claim 2 , wherein

the metal-plating layers are made of a metal material having a conductivity higher than a conductivity of the metal tape.

5. The waveguide according to claim 1 , wherein

a cross-sectional shape of the dielectric perpendicular to a waveguide direction is a rectangle, and two surfaces including longer sides of the cross section are the two surfaces, the electric field intersecting with the two surfaces.

6. The waveguide according to claim 5 , wherein

the rectangular cross-section of the dielectric has arc-shaped corners.

7. The waveguide according to claim 5 , wherein

the dielectric has two arc-shaped surfaces including shorter sides of the rectangular cross-section.

8. The waveguide according to claim 1 , wherein

a cross-sectional shape of the dielectric perpendicular to a waveguide direction is an elliptical shape, and two surfaces of the cross-section having a larger curvature are the two surfaces, the electric field intersecting with the two surfaces.

9. The waveguide according to claim 1 , wherein

the waveguide is configured to transmit a high-frequency signal.

10. The waveguide according to claim 9 , wherein

the high-frequency signal is a millimeter-waveband signal.

11. A waveguide manufacturing method, comprising:

a step of metal-plating layers coating two surfaces of a dielectric, an electric field intersecting with the two surfaces; and

a step of winding up a protective layer made of a sheet-like conductor around the dielectric including the two surfaces coated with the metal-plating layers to thereby coat a periphery of the dielectric including the two metal-plated surfaces with the protective layer, in this order.

12. The waveguide manufacturing method according to claim 11 , wherein

the dielectric has a sheet-like shape, and

the step of metal-plating includes metal-plating both surfaces of the sheet-like dielectric.

13. The waveguide manufacturing method according to claim 12 , further comprising:

the step of cutting the sheet-like dielectric having both the metal-plated surfaces into strips each having a predetermined width.

14. The waveguide manufacturing method according to claim 13 , wherein

the step of coating with the protective layer includes winding up a sheet-like conductor around the dielectric, the dielectric being metal-plated and cut in a strip.

15. The waveguide manufacturing method according to claim 14 , wherein

the sheet-like conductor is a metal tape.

16. A wireless transmission system, comprising:

a sender configured to send a high-frequency signal;

a receiver configured to receive the high-frequency signal; and

a waveguide configured to transmit the high-frequency signal between the sender and the receiver, wherein

the waveguide includes

a dielectric including two surfaces, an electric field intersecting with the two surfaces,

metal-plating layers coating the two surfaces of the dielectric, the electric field intersecting with the two surfaces, and

a protective layer coating a periphery of the dielectric including the two surfaces coated with the metal-plating layers, and

the protective layer includes a sheet-like conductor wound up around the dielectric including the two surfaces coated with the metal-plating layers.

17. The wireless transmission system according to claim 16 , wherein

the high-frequency signal is a millimeter-waveband signal.