Radio-over-fiber transponder with a dual-band patch antenna system

• US 20080044186A1
• Filed: 08/16/2006
• Published: 02/21/2008
• Est. Priority Date: 08/16/2006
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Corning Cable Systems LLC (Corning Incorporated)
• Inventors: George, Jacob, Sauer, Michael, Zenteno, Luis A.
• Granted Patent: US 7,627,250 B2
• Time in Patent Office: Days
• US Class Current: 398/115
• CPC Class Codes: H04B 10/25754 Star network topology
• CPC Class Codes: H04B 10/25759 Details of the reception of RF signal or the optical conversion before the optical fibre

Abstract

The radio-over-fiber (RoF) transponder includes a converter unit adapted to convert RF electrical signals into optical signals and vice versa, and an antenna system electrically coupled to the converter unit. The antenna system includes first and second Z-shaped patch antenna elements formed on an antenna substrate. These patches are adapted to respectively transmit and receive radio-frequency (RF) electromagnetic radiation at a first frequency f_A (e.g., 2.4 GHz) over a first picocell. The antenna system also includes a square patch antenna element formed atop the antenna substrate surface between the first and second Z-shaped patch antenna elements. The square patch antenna is adapted to transmit and receive RF electromagnetic radiation at a second frequency f_B (e.g., 5.2 GHz) over a second picocell substantially co-located with the first picocell. One or more spaced-apart transponders can be supported by one or more optical fibers to form an array of picocells.

Claims

1. A radio-over-fiber (RoF) transponder, comprising:

a converter unit adapted to convert RF electrical signals into optical signals and vice versa;

an antenna system electrically coupled to the converter unit, the antenna system having an antenna substrate with a surface;

first and second patch antenna elements formed on the antenna substrate surface and adapted to respectively transmit and receive radio-frequency (RF) electromagnetic radiation at a first frequency f_A over a first picocell; and

a third patch antenna element formed on the antenna substrate surface and adapted to transmit and receive RF electromagnetic radiation at a second frequency f_B over a second picocell that at least substantially overlaps the first picocell.

2. The transponder of claim 1, wherein the first and second patch antenna elements define Z-shaped patch antenna elements and wherein the third patch antenna element defines a square patch antenna element.

3. The transponder of claim 1, wherein the third patch antenna element is formed on the antenna substrate surface between the first and second patch antenna elements.

4. The transponder of claim 1, wherein f_A is a frequency in a 2.4 GHz band and f_B is a frequency in a 5.2 GHz band.

5. The transponder of claim 1, wherein the converter unit includes:

first and second E/O converters that convert an electrical RF signal into an optical RF signal for respective first and second frequencies f_A and f_B; and

first and second O/E converters that convert an optical RF signal into an electrical RF signal for the first and second frequencies f_A and f_B, respectively.

6. The transponder of claim 5, including:

first and second downlink optical fibers respectively optically coupled to the first and second O/E converters and adapted to carry downlink RF optical signals having frequency f_A and f_B, respectively; and

first and second uplink optical fibers respectively optically coupled to the first and second E/O converters and adapted to carry downlink RF optical signals having frequencies f_A and f_B, respectively.

7. The transponder of claim 1, wherein the converter unit includes:

an E/O converter that includes a sub-carrier multiplexing (SCM) transmitter adapted to sub-carrier multiplex uplink electrical RF signals of respective frequencies f_A and f_B onto a sub-carrier multiplexed (SCM) uplink electrical signal, the E/O convert adapted to convert the SCM uplink electrical signal into an SCM uplink optical signal; and

an O/E converter adapted to receive an SCM downlink optical signal and covert it to an SCM downlink electrical signal, the O/E converter having an SCM receiver adapted to receive and demultiplex the SCM downlink electrical signal to obtain downlink electrical RF signals of respective frequencies f_A and f_B.

8. The transponder of claim 7, further including:

a downlink optical fiber optically coupled to the O/E converter and adapted to carry the SCM downlink optical signal; and

an uplink optical fiber optically coupled to the E/O converter and adapted to carry the SCM uplink optical signal.

9. The transponder of claim 1, further including a conductive ground layer operatively arranged between the antenna substrate and the converter unit.

10. The transponder of claim 1, wherein at least one of the first and second patch antenna elements has a single antenna port, and the third patch antenna element has two antenna ports.

11. A radio-over-fiber (RoF) optical fiber cable, comprising:

an outer protective jacket;

one or more optical fiber communication links supported at least substantially within the outer protective jacket;

one or more spaced apart transponders according to claim 6 arranged to form an array of corresponding one or more first and second picocells in response to corresponding one or more of the downlink optical RF signals being provided to the corresponding one or more transponders, wherein picocells of adjacent transponders do not substantially interfere.

12. The optical fiber of claim 11, wherein the transponders are located within the outer protective jacket.

13. A radio-over-fiber (RoF) optical fiber cable, comprising:

an outer protective jacket;

one or more optical fiber communication links supported at least substantially within the outer protective jacket;

one or more spaced apart transponders according to claim 8 arranged to form an array of corresponding one or more first and second picocells in response to corresponding one or more of the SCM downlink optical signals being provided to the corresponding one or more transponders, wherein the picocells of adjacent transponders do not substantially interfere.

14. The optical fiber of claim 11, wherein the transponders are located within the outer protective jacket.

15. A radio-over-fiber (RoF) picocellular wireless system, comprising:

a head-end station adapted to provide first and second downlink RF optical signals having respective first and second frequencies f_A and f_B, and adapted to receive and process first and second uplink RF optical signals having respective first and second frequencies f_A and f_B;

an optical fiber cable optically coupled to the head-end station, the optical fiber cable having one or more optical fiber communication links adapted to carry the first and second downlink RF optical signals and the first and second uplink optical signals;

one or more transponders respectively optically coupled to the corresponding one or more optical fiber communication links, with at least one transponder having a converter unit adapted to convert RF optical signals to RF electrical signals and vice versa; and

wherein at least one transponder includes a micro-strip antenna system with first and second patch antenna elements adapted to respectively transmit and receive RF electromagnetic radiation at the first frequency f_A over a first picocell, and a third patch antenna element adapted to transmit and receive RF electromagnetic radiation at the second frequency f_B over a second picocell substantially co-located with the first picocell, and wherein picocells of adjacent transponders do not substantially interfere.

16. The system of claim 15, wherein:

at least one transponder includes first and second optical fiber ports, and at least one optical communication link includes a downlink optical fiber coupled to the first optical fiber port and an uplink optical fiber optically coupled to the second port; and

wherein at least one transponder is adapted to (a) perform sub-carrier multiplexing of first and second uplink electrical signals of frequencies f_A and f_B, and (b) perform sub-carrier de-multiplexing of first and second uplink electrical signals of frequencies f_A and f_B.

17. The system of claim 15, wherein the optical fiber cable is arranged above a ceiling of a room.

18. The system of claim 15, wherein the first frequency f_A is in a 2.4 GHz band and the second frequency f_B is in a 5.2 GHz band.

19. The transponder of claim 15, wherein the first and second patch antenna elements define Z-shaped patch antenna elements and wherein the third patch antenna element defines a square patch antenna element.

20. The transponder of claim 15, wherein the third patch antenna element is formed on the antenna substrate surface between the first and second patch antenna elements.

21. A method of generating first and second substantially co-located first and second picocells at respective first and second frequencies, comprising:

providing first and second downlink optical signals of respective first and second frequencies f_A and f_B to a radio-over-fiber (RoF) transponder;

at the transponder, converting the first and second downlink optical signals to corresponding first and second electrical signals;

feeding the first electrical downlink signals to first and second patch antenna elements adapted to transmit at the first frequency f_A so as to form a first picocell; and

feeding the second electrical downlink signals to a third patch antenna element adapted to transmit at the second frequency f_B so as to form a second picocell substantially co-located with the first picocell.

22. The method of claim 21, including operably supporting one or more transponders with an optical fiber cable, thereby forming an array of co-located first and second picocells, wherein picocells of adjacent transponders do not substantially intefere.

23. The method of claim 21, including:

performing sub-carrier multiplexing on the first and second downlink electrical signals at a head-end station operably coupled to the transponder;

providing the first and second downlink optical signals to the transponder as a sub-carrier multiplexed optical signal; and

performing sub-carrier de-multiplexing at the transponder to recover the first and second downlink electrical signals.

24. The method of claim 21, including communicating with one or more client devices with the first and/or second picocells at the first and/or second wavelength by exchanging first and/or second downlink and uplink electromagnetic signals of corresponding first and/or second frequencies f_A and f_B, between the transponder and the one or more client devices.