Apparatus and methods for dynamic impedance matching of a guided wave launcher

• US 10,470,053 B2
• Filed: 05/07/2019
• Issued: 11/05/2019
• Est. Priority Date: 02/27/2017
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Rappaport, Harold Lee
• Primary Examiner(s): Tran, Khanh C
• Application Number:
  US16/405,044
• Publication Number:
  US 20190261192A1
• Time in Patent Office: 182 Days
• CPC Class Codes: H01P 5/04 with variable factor of coupling
• CPC Class Codes: H01P 7/08 Strip line resonators
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H04B 3/04 Control of transmission; Equalising
• CPC Class Codes: H04B 3/36 Repeater circuits H04B3/58 takes precedence
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04B 3/52 Systems for transmission between fixed stations via waveguides
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04W 16/18 Network planning tools

Abstract

Aspects of the subject disclosure may include, for example, a guided wave launcher generates, in response to an output RF signal, a guided electromagnetic wave along a surface of a transmission medium, wherein the guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path, and wherein the guided electromagnetic wave has a non-optical carrier frequency. A mismatch probe generates a mismatch signal based on the output RF signal, wherein the mismatch signal indicates an impedance mismatch of the guided wave launcher. A controller generates one or more control signals in response to the mismatch signal, wherein the one or more control signals adjust one or more adjustable circuit elements of an impedance matching circuit, wherein adjustment of the one or more adjustable circuit elements facilitates reducing the impedance mismatch of the guided wave launcher. Other embodiments are disclosed.

Claims

1. A waveguide device, comprising:

an impedance matching circuit that includes one or more adjustable elements, wherein the impedance matching circuit receives an input signal and generates an output signal in response to the input signal;

a guided wave launcher configured to generate, in response to the output signal, a guided electromagnetic wave outside a surface of a transmission medium, wherein the guided electromagnetic wave propagates along the outside the surface of the transmission medium without requiring an electrical return path, and wherein the guided electromagnetic wave has a non-optical carrier frequency;

a mismatch probe configured to generate a mismatch signal based on the output signal, wherein the mismatch signal indicates an impedance mismatch of the guided wave launcher; and

a controller configured to adjust the one or more adjustable elements of the impedance matching circuit, wherein an adjustment of the one or more adjustable elements facilitates reducing the impedance mismatch of the guided wave launcher.

2. The waveguide device of claim 1, wherein the impedance matching circuit is configured as a pi-network, an L-network or a T-network.

3. The waveguide device of claim 1, wherein the one or more adjustable elements include one or more adjustable impedances.

4. The waveguide device of claim 3, wherein the one or more adjustable impedances include an adjustable capacitor or an adjustable inductor.

5. The waveguide device of claim 3, wherein the one or more adjustable impedances include a plurality of adjustable impedances.

6. The waveguide device of claim 1, wherein the one or more adjustable elements include a tunable transformer.

7. The waveguide device of claim 1, wherein the mismatch probe includes a voltage detector, a standing wave ratio meter, a directional coupler or a reflectometer.

8. The waveguide device of claim 1, wherein the controller includes a look-up table.

9. The waveguide device of claim 1, wherein the guided electromagnetic wave is modulated via a wideband modulating signal and the impedance matching circuit provides a wideband impedance matching of a transmitter to the guided wave launcher.

10. The waveguide device of claim 1, wherein the guided wave launcher has an impedance that changes based on a weather condition in an area of the transmission medium and wherein the one or more adjustable elements of the impedance matching circuit are adjusted to compensate for the impedance that changes based on the weather condition in the area of the transmission medium.

11. The waveguide device of claim 1, wherein the guided wave launcher is a horn launcher, a stripline launcher, a non-coaxial launcher, a reflective launcher, a slot launcher or a spiral launcher.

12. The waveguide device of claim 1, wherein the guided electromagnetic wave has a range of frequencies below 10 GHz.

13. The waveguide device of claim 1, wherein the guided electromagnetic wave has a range of frequencies in a millimeter wave frequency band.

14. A method, comprising:

receiving an input signal at an impedance matching circuit from a transmitter;

generating, via the impedance matching circuit, an output signal in response to the input signal;

generating, in response to the output signal and via a guided wave launcher, a guided electromagnetic wave outside a surface of a transmission medium, wherein the guided electromagnetic wave propagates along the outside the surface of the transmission medium without requiring an electrical return path, and wherein the transmission medium is opaque to optical signals;

generating a mismatch signal based on the output signal, wherein the mismatch signal indicates an impedance mismatch of the guided wave launcher; and

adjusting, in response to the mismatch signal, one or more adjustable circuit elements of the impedance matching circuit, wherein the adjusting facilitates reducing the impedance mismatch of the guided wave launcher to compensate for impedance changes of the guided wave launcher resulting from changing weather conditions in an area of the transmission medium.

15. The method of claim 14, wherein the impedance matching circuit is configured as a pi-network, an L-network or a T-network.

16. The method of claim 14, wherein the one or more adjustable circuit elements include an adjustable capacitor or an adjustable inductor.

17. The method of claim 14, wherein the one or more adjustable circuit elements include a tunable transformer.

18. The method of claim 14, wherein the one or more adjustable circuit elements include a plurality of adjustable circuit elements.

19. A device, comprising:

circuit means for receiving an input signal at an impedance matching circuit and generating an output signal in response to the input signal;

launcher means for generating, in response to the output signal, a guided electromagnetic wave outside a surface of a transmission medium, wherein the guided electromagnetic wave propagates along the outside the surface of the transmission medium without requiring an electrical return path, and wherein the guided electromagnetic wave has a non-optical carrier frequency;

probe means for generating a mismatch signal based on the output signal, wherein the mismatch signal indicates an impedance mismatch of the launcher means; and

controller means for adjusting an impedance of the circuit means, wherein the impedance reduces the impedance mismatch of the launcher means.

20. The device of claim 19, wherein an impedance of the launcher means changes based on a weather condition in an area of the transmission medium and wherein the impedance of the circuit means is adjusted to compensate for changes of the impedance of the launcher means.