RF/optical shared aperture for high availability wideband communication RF/FSO links
An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.
1. An apparatus, comprising:
a first reflecting element comprising a concave primary mirror that has an inner perimeter and an outer perimeter and a first curvature, wherein said first reflecting element further comprises a concave secondary mirror disposed within said inner perimeter, wherein said secondary mirror comprises a central aperture and a second curvature that is greater than said first curvature;
a folding mirror facing said secondary mirror, wherein said folding mirror is configured to transmit a radio-frequency signal (RFS) and is further configured to reflect an optical signal (OS); and
a compensating element configured to transmit said RFS, wherein said folding mirror is located between said compensating element and said first reflecting element.
2. The apparatus of claim 1 , wherein said folding mirror comprises a dichroic material.
3. The apparatus of claim 1 , wherein said folding mirror and said compensating element are located between said primary mirror and the focal point of said primary mirror.
4. The apparatus of claim 1 , further comprising a source of said OS.
5. The apparatus of claim 4 , wherein said OS comprises a wavelength of 1550 nm.
6. The apparatus of claim 1 , wherein said OS and said RFS each propagate from a different focal point of said primary mirror.
7. The apparatus of claim 6 , wherein said folding mirror and said primary mirror are configured and positioned to collimate said OS as is exits said apparatus.
8. The apparatus of claim 4 , further comprising a source of said RFS.
9. The apparatus of claim 8 , wherein said source of said RFS comprises a millimeter-wave scalar feed horn antenna.
10. The apparatus of claim 1 , wherein said compensating element comprises dielectric material.
11. The apparatus of claim 1 , wherein said compensating element comprises a compensating curvature configured such that said RFS will be collimated as it exits said apparatus.
12. The apparatus of claim 1 , wherein said folding mirror and said compensating element are in contact.
13. The apparatus of claim 1 , wherein diameters of said folding mirror, said compensating element and said secondary mirror are equal.
14. A method, comprising:
providing an apparatus, comprising:
a first reflecting element comprising a concave primary mirror that has an inner perimeter and an outer perimeter and a first curvature, wherein said first reflecting element further comprises a concave secondary mirror disposed within said inner perimeter, wherein said secondary mirror comprises a central aperture and a second curvature that is greater than said first curvature;
a folding mirror facing said secondary mirror, wherein said folding mirror is configured to transmit a radio-frequency signal (RFS) and is further configured to reflect an optical signal (OS); and
a compensating element configured to transmit said RFS, wherein said folding mirror is located between said compensating element and said first reflecting element;
transmitting said RFS through said compensating element and said folding mirror; and
reflecting said OS from said folding mirror.