Enhanced guided surface waveguide probe

1. A method, comprising:

positioning a charge terminal at a defined height over a lossy conducting medium, the charge terminal comprising a upper terminal portion coupled to a lower terminal portion through a variable capacitance;

adjusting a phase delay (Φ) of a feed network connected to the charge terminal to match a wave tilt angle (Ψ) corresponding to a complex Brewster angle of incidence (θ i,B ) associated with the lossy conducting medium;

adjusting the variable capacitance of the charge terminal based upon an image ground plane impedance (Z in ) associated with the lossy conducting medium; and

exciting the charge terminal with an excitation voltage via the feed network, where the excitation voltage establishes an electric field that couples into a guided surface waveguide mode along a surface of the lossy conducting medium.

2. The method of claim 1 , wherein the variable capacitance of the charge terminal is adjusted based upon a reactive component of the image ground plane impedance (Z in ).

3. The method of claim 2 , wherein the variable capacitance of the charge terminal is adjusted to match the reactive component of the image ground plane impedance (Z in ) with a structure impedance (Z base ) associated with the feed network and the charge terminal.

4. The method of claim 1 , wherein the phase delay (Φ) of the feed network is fixed while the variable capacitance of the charge terminal is adjusted.

5. The method of claim 1 , wherein the feed network comprises a feed line conductor coupled to the charge terminal and a coil coupled between the lossy conducting medium and the feed line conductor, where the phase delay (Φ) of the feed network includes a phase delay (θ y ) associated with the feed line conductor and a phase delay (θ c ) associated with the coil.

6. The method of claim 1 , wherein the complex Brewster angle of incidence (θ i,B ) associated with the lossy conducting medium is based upon an operational frequency of the excitation voltage and characteristics of the lossy conducting medium.

7. The method of claim 6 , wherein the characteristics of the lossy conducting medium include conductivity and permittivity.

8. The method of claim 1 , wherein the image ground plane impedance (Z in ) is based at least in part upon a phase shift (θ d ) between a physical boundary of the lossy conducting medium and a conducting image ground plane.

9. The method of claim 8 , wherein the physical boundary of the lossy conducting medium and the conducting image ground plane are separated by a complex depth.

10. The method of claim 1 , comprising:

sensing a change in a characteristic of the lossy conducting medium;

adjusting the phase delay (Φ) of the feed network connected to the charge terminal to match a modified wave tilt angle in response to the change in the characteristic of the lossy conducting medium, the modified wave tilt angle corresponding to a complex Brewster angle of incidence associated with the lossy conducting medium having the changed characteristic; and

adjusting the variable capacitance of the charge terminal based upon a new image ground plane impedance that is based upon the lossy conducting medium having the changed characteristic.

11. The method of claim 1 , wherein the lossy conducting medium is a terrestrial medium.

12. A guided surface waveguide probe, comprising:

a charge terminal elevated over a lossy conducting medium, the charge terminal comprising a upper terminal portion coupled to a lower terminal portion through a variable capacitance; and

a feed network configured to couple an excitation source to the charge terminal, the feed network configured to provide a voltage to the charge terminal with a phase delay (Φ) that matches a wave tilt angle (Ψ) associated with a complex Brewster angle of incidence (θ i,B ) associated with the lossy conducting medium, and the variable capacitance is determined based upon an image ground plane impedance (Z in ) associated with the lossy conducting medium.

13. The guided surface waveguide probe of claim 12 , wherein the feed network comprises a feed line conductor coupled to the charge terminal and a coil coupled between the lossy conducting medium and the feed line conductor, where the phase delay (Φ) of the feed network includes a phase delay (θ y ) associated with the feed line conductor and a phase delay (θ c ) associated with the coil.

14. The guided surface waveguide probe of claim 13 , wherein the coil is a helical coil.

15. The guided surface waveguide probe of claim 13 , wherein the charge terminal is coupled to the coil via a tap connection.

16. The guided surface waveguide probe of claim 12 , wherein the feed network is configured to vary the phase delay (Φ) to match the wave tilt angle (Ψ).

17. The guided surface waveguide probe of claim 12 , comprising a probe control system configured to adjust the feed network based at least in part upon characteristics of the lossy conducting medium.

18. The guided surface waveguide probe of claim 17 , wherein the probe control system adjusts the variable capacitance in response to a change in the characteristics of the lossy conducting medium.

19. The guided surface waveguide probe of claim 18 , wherein the probe control system adjusts the phase delay (Φ) of the feed network to match a modified wave tilt angle in response to the change in the characteristics of the lossy conducting medium prior to adjusting the variable capacitance, the modified wave tilt angle corresponding to a complex Brewster angle of incidence associated with the lossy conducting medium having the changed characteristics.

20. The guided surface waveguide probe of claim 18 , wherein the variable capacitance of the charge terminal is adjusted to match a reactive component of the image ground plane impedance (Z in ) with a structure impedance (Z base ) associated with the feed network and the charge terminal.