Subsurface sensing using guided surface wave modes on lossy media
Disclosed are various systems and methods for remote surface sensing using guided surface wave modes on lossy media. One system, among others, comprises a guided surface waveguide probe configured to launch a guided surface wave along a surface of a lossy conducting medium, and a receiver configured to receive backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave. One method, among others, includes launching a guided surface wave along a surface of a lossy conducting medium by exciting a charge terminal of a guided surface waveguide probe, and receiving backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave.
1. A system, comprising:
a guided surface waveguide probe configured to launch a guided surface wave along a surface of a lossy conducting medium, wherein the guided surface waveguide probe comprises a charge terminal elevated over the lossy conducting medium configured to generate at least one resultant field that synthesizes a wave front incident with the surface at a complex Brewster angle of incidence (θ i,B ) of the lossy conducting medium; and
a receiver configured to receive backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave.
2. The system of claim 1 , wherein the charge terminal is one of a plurality of charge terminals.
3. The system of claim 1 , wherein the guided surface waveguide probe comprises a feed network electrically coupled to the charge terminal, the feed network providing a phase delay (Φ) that matches a wave tilt angle (Ψ) associated with the complex Brewster angle of incidence (θ i,B ) associated with the lossy conducting medium in a vicinity of the guided surface waveguide probe.
4. The system of claim 3 , wherein the charge terminal is one of a plurality of charge terminals.
5. The system of claim 4 , wherein the feed network is configured to impose a plurality of voltage magnitudes and a plurality of phases on the plurality of charge terminals to synthesize a plurality of fields that substantially match a guided surface-waveguide mode of the lossy conducting medium, thereby launching the guided surface wave.
6. The system of claim 1 , wherein the guided surface waveguide probe is configured to launch a series of guided surface waves having a defined pulse duration at a defined repetition rate.
7. The system of claim 1 , wherein the guided surface wave is a frequency modulated continuous wave.
8. The system of claim 1 , wherein the remotely located subsurface object is an item buried in the lossy conducting medium.
9. The system of claim 1 , wherein the remotely located subsurface object is a geological feature of the lossy conducting medium.
10. The system of claim 1 , wherein the receiver is the guided surface waveguide probe.
11. The system of claim 1 , comprising a plurality of guided surface waveguide probes configured to launch guided surface waves along the surface of the lossy conducting medium.
12. The system of claim 1 , comprising a plurality of receivers configured to receive backscatter reflected by the remotely located subsurface object illuminated by the guided surface wave.
13. The system of claim 1 , wherein the lossy conducting medium is a terrestrial medium.
14. The system of claim 1 , comprising a mobile vehicle including the receiver.
15. A method, comprising:
launching a guided surface wave along a surface of a lossy conducting medium by exciting a charge terminal of a guided surface waveguide probe, where excitation of the charge terminal generates a resultant field that synthesizes a wave front incident with the surface at a complex Brewster angle of incidence (θ i,B ) of the lossy conducting medium; and
receiving backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave.
16. The method of claim 15 , wherein the guided surface waveguide probe comprises a feed network electrically coupled to the charge terminal, the feed network providing a phase delay (Φ) that matches a wave tilt angle (Ψ) associated with the complex Brewster angle of incidence (θ i,B ) associated with the lossy conducting medium in a vicinity of the guided surface waveguide probe.
17. The method of claim 15 , wherein the guided surface waveguide probe is configured to launch a series of guided surface waves having a defined pulse duration at a defined repetition rate.
18. The method of claim 15 , comprising determining a characteristic of the remotely located subsurface object based at least in part upon the backscatter.
19. The method of claim 15 , wherein the guided surface wave is a frequency modulated continuous wave.
20. The method of claim 15 , wherein the lossy conducting medium is a terrestrial medium.