Subsurface sensing using guided surface wave modes on lossy media

Abstract

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.

Therefore, the following is claimed: 
     
         1 . A method, comprising:
 launching a guided surface wave along a surface of a lossy conducting medium in a Zenneck waveguide mode by exciting one or more charge terminal of a guided surface waveguide probe; and   receiving backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave.   
     
     
         2 . The method of  claim 1 , wherein excitation of the one or more charge terminal generates a resultant field that synthesizes a wave front incident at a complex Brewster angle of incidence (θ i,B ) of the lossy conducting medium. 
     
     
         3 . The method of  claim 2 , wherein the guided surface waveguide probe comprises a feed network electrically coupled to the one or more charge terminal, the feed network providing excitation to individual charge terminals of the one or more charge terminal. 
     
     
         4 . The method of  claim 3 , wherein the feed network is configured to impose voltage magnitudes and phases on the individual charge terminals to synthesize a resultant field that substantially matches the Zenneck waveguide mode of the lossy conducting medium, thereby launching the guided surface wave. 
     
     
         5 . The method of  claim 1 , wherein the backscatter reflected by the remotely located subsurface object is received by a receiver. 
     
     
         6 . The method of  claim 5 , wherein the backscatter reflected by the remotely located subsurface object is received by an array of receivers including the receiver. 
     
     
         7 . The method of  claim 6 , wherein the array of receivers comprises the guided surface waveguide probe. 
     
     
         8 . The method of  claim 1 , wherein the backscatter reflected by the remotely located subsurface object is received by the guided surface waveguide probe. 
     
     
         9 . The method 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. 
     
     
         10 . The method of  claim 1 , wherein the guided surface wave is a frequency modulated continuous wave. 
     
     
         11 . The method of  claim 1 , comprising launching guided surface waves along the surface of a lossy conducting medium in the Zenneck waveguide mode by exciting charge terminals of an array of guided surface waveguide probes, the array of guided surface waveguide probes comprising the guided surface waveguide probe; and
 receiving backscatter reflected by the remotely located subsurface object illuminated by the guided surface waves.   
     
     
         12 . The method of  claim 11 , wherein the array of guided surface waveguide probes is configured to focus the guided surface waves in at least one direction. 
     
     
         13 . The method of  claim 11 , wherein the array of guided surface waveguide probes is configured to increase a field strength of the guided surface waves in at least one direction. 
     
     
         14 . The method of  claim 1 , wherein the remotely located subsurface object is a subsurface feature of the lossy conducting medium. 
     
     
         15 . The method of  claim 14 , wherein the lossy conducting medium is a terrestrial medium, and the subsurface feature is a variation in the terrestrial medium. 
     
     
         16 . The method of  claim 1 , comprising determining a characteristic of the remotely located subsurface object based at least in part upon the backscatter. 
     
     
         17 . A system, comprising:
 a guided surface waveguide probe configured to launch a guided surface wave along a surface of a lossy conducting medium by substantially mode-matching to a Zenneck waveguide mode 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.   
     
     
         18 . The system of  claim 17 , comprising an array of guided surface waveguide probes including the guided surface waveguide probe, the array of guided surface waveguide probes configured to launch guided surface waves along the surface of a lossy conducting medium in the Zenneck waveguide mode. 
     
     
         19 . The system of  claim 17 , comprising a plurality of receivers comprising the receiver, the plurality of receivers configured to receive backscatter reflected by the remotely located subsurface object illuminated by the guided surface wave. 
     
     
         20 . The system of  claim 17 , wherein the lossy conducting medium is a terrestrial medium, and the remotely located subsurface object is a subsurface feature of the terrestrial substrate.