System and method for launching guided electromagnetic waves with impedance matching

• US 10,305,192 B1
• Filed: 08/13/2018
• Issued: 05/28/2019
• Est. Priority Date: 08/13/2018
• 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:
  US16/102,262
• Time in Patent Office: 288 Days
• CPC Class Codes: H01P 3/10 Wire waveguides, i.e. with a single solid longitudinal conductor
• CPC Class Codes: H01P 3/12 Hollow waveguides H01P3/20 takes precedence
• CPC Class Codes: H01P 3/16 Dielectric waveguides, i.e. without a longitudinal conductor
• CPC Class Codes: H01Q 1/12 Supports; Mounting means
• CPC Class Codes: H01Q 13/02 Waveguide horns
• CPC Class Codes: H01Q 19/08 for modifying the radiation pattern of a radiating horn in which it is located corrugated horns H01Q13/0208; producing a circular polarisation H01Q13/0241
• CPC Class Codes: H01Q 21/064 using horn or slot aerials slotted waveguides arrays H01Q21/005
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 3/30 varying the relative phase between the radiating elements of an array H01Q3/2605, H01Q3/2658, H01Q3/2682, H01Q3/44 take precedence
• CPC Class Codes: H01Q 3/36 with variable phase-shifters
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating
• CPC Class Codes: H04B 3/38 for signals in two different frequency ranges transmitted in opposite directions over the same transmission path
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04B 3/546 Combination of signalling, telemetering, protection circuits for remote indication of supply or distribution network condition H02J13/00
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals

Abstract

In accordance with one or more embodiments, a system includes an impedance matching circuit that includes one or more adjustable circuit 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 is configured to generate, in response to the output signal, a first guided electromagnetic wave along a surface of a transmission medium, wherein the first guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path. A controller is configured to generate one or more control signals in response to a channel quality indicator, wherein the one or more control signals adjust the one or more adjustable circuit elements of the impedance matching circuit, wherein adjustment of the one or more adjustable circuit elements facilitates reducing an impedance mismatch of the guided wave launcher.

Claims

1. A system, comprising:

an impedance matching circuit that includes one or more adjustable circuit 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 first guided electromagnetic wave along a surface of a transmission medium, wherein the first guided electromagnetic wave propagates along the surface of the transmission medium without requiring an electrical return path, and wherein the first guided electromagnetic wave is within a non-optical frequency band;

a controller configured to generate one or more control signals in response to a channel quality indicator, wherein the channel quality indicator is received via a second guided electromagnetic wave from a remote launcher, wherein the one or more control signals adjust the one or more adjustable circuit elements of the impedance matching circuit, wherein adjustment of the one or more adjustable circuit elements facilitates reducing an impedance mismatch of the guided wave launcher.

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

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

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

5. The system of claim 3, wherein the one or more adjustable impedances include a plurality of adjustable impedances, wherein the one or more control signals include a plurality of control signals and wherein each of the plurality of control signals controls a corresponding one of the plurality of adjustable impedances.

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

7. The system of claim 1, wherein the transmission medium includes a bare or insulated wire.

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

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

10. The system of claim 1, wherein the channel quality indicator indicates changes in a transmission channel from the system to a remote device based on a weather condition in an area of the transmission medium and wherein the one or more control signals adjust the impedance of the impedance matching circuit to compensate for changes of the transmission channel.

11. The system 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 system of claim 1, wherein the first guided electromagnetic wave has a range of frequencies below 10 GHz.

13. The system of claim 1, wherein the first 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 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 transmission medium is opaque to optical signals;

receiving a channel quality indicator via a second guided electromagnetic wave from a remote launcher;

generating one or more control signals in response to the channel quality indicator; and

adjusting, in response to the one or more control signals, one or more adjustable circuit elements of the impedance matching circuit, wherein the adjusting compensates 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, wherein the one or more control signals include a plurality of control signals and wherein each of the plurality of control signals controls a corresponding one of the plurality of adjustable circuit elements.

19. A device, comprising:

circuit means for receiving an input radio 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 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;

controller means for generating one or more control signals in response to a channel quality indicator received via a second guided electromagnetic wave from a remote launcher, wherein the one or more control signals adjust an impedance of the circuit means, wherein the impedance reduces an impedance mismatch of the launcher means.

20. The device of claim 19, wherein the channel quality indicator indicates changes in a transmission channel from the device to a remote device based on a weather condition in an area of the transmission medium and wherein the one or more control signals adjust the impedance of the circuit means to compensate for changes of the transmission channel.