Excitation and use of guided surface waves

Abstract

Disclosed are various embodiments for transmitting and receiving energy conveyed in the form of a guided surface-waveguide mode along the surface of a lossy medium such as, e.g., a terrestrial medium excited by a guided surface waveguide probe.

Therefore, the following is claimed: 
     
         1 . A method, comprising:
 positioning a charge terminal at a height over a lossy conducting medium;   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; 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 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. 
     
     
         3 . The method of  claim 2 , wherein adjusting the phase delay (Φ) comprises adjusting the phase delay (θ c ) associated with the coil. 
     
     
         4 . The method of  claim 3 , wherein a connection of the feed line conductor is repositioned on the coil to adjust the phase delay (θ c ) associated with the coil. 
     
     
         5 . The method of  claim 4 , wherein the connection of the feed line conductor is repositioned on the coil via a variable tap. 
     
     
         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) 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 , further comprising:
 adjusting a load impedance (Z L ) of the charge terminal based based upon a reactive component of the image ground plane impedance (Z in ).   
     
     
         11 . The method of  claim 10 , wherein the load impedance (Z L ) 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. 
     
     
         12 . The method of  claim 1 , wherein:
 the phase delay (Φ) of the feed network is fixed; and   the method further comprises adjusting a load impedance (Z L ) of the charge terminal based upon an image ground plane impedance (Z in ) associated with the lossy conducting medium.   
     
     
         13 . The method of  claim 1 , wherein the charge terminal has an effective spherical diameter, and the height of the charge terminal is at least four times an effective spherical diameter to reduce bound capacitance. 
     
     
         14 . The method of  claim 1 , wherein the charge terminal is coupled to an excitation source via a coil. 
     
     
         15 . The method of  claim 1 , comprising:
 sensing a change in a characteristic of the lossy conducting medium; and   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 the complex Brewster angle of incidence (θ i,B ) associated with the lossy conducting medium having the changed characteristic.   
     
     
         16 . The method of  claim 15 , comprising:
 adjusting the load impedance (Z L ) of the charge terminal based upon a new image ground plane impedance based upon the lossy conducting medium having the changed characteristic.   
     
     
         17 . The method of  claim 1 , wherein the lossy conducting medium is a terrestrial medium. 
     
     
         18 . A guided surface waveguide probe, comprising:
 a charge terminal elevated over a lossy conducting medium, the charge terminal having a load impedance (Z L ) that is determined based upon an image ground plane impedance (Z 1n ) associated with the lossy conducting medium; 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.   
     
     
         19 . The guided surface waveguide probe of  claim 18 , 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. 
     
     
         20 . The guided surface waveguide probe of  claim 19 , wherein the coil is a helical coil. 
     
     
         21 . The guided surface waveguide probe of  claim 19 , wherein the excitation source is coupled to the coil via a tap connection. 
     
     
         22 . The guided surface waveguide probe of  claim 21 , wherein an impedance matching network is coupled between the excitation source and the tap connection on the coil. 
     
     
         23 . The guided surface waveguide probe of  claim 19 , wherein the excitation source is at least one of magnetically coupled to the coil or coupled to the coil via a tap connection. 
     
     
         24 . The guided surface waveguide probe of  claim 18 , wherein the feed network is configured to vary the phase delay (Φ) to match the wave tilt angle ( 1 ′). 
     
     
         25 . The guided surface waveguide probe of  claim 18 , comprising a probe control system configured to adjust the feed network based at least in part upon characteristics of the lossy conducting medium. 
     
     
         26 . The guided surface waveguide probe of  claim 25 , wherein the feed network comprises a coil coupled between the excitation source and the charge terminal, the charge terminal coupled to the coil via a variable tap. 
     
     
         27 . The guided surface waveguide probe of  claim 26 , wherein the probe control system adjusts a position of the variable tap in response to a change in the characteristics of the lossy conducting medium. 
     
     
         28 . A method comprising:
 positioning a charge terminal of a guided surface waveguide probe at a height over a lossy conducting medium;   adjusting a traveling wave phase delay (Φ) of the guided surface waveguide probe to match a wave-tilt angle (Ψ) of a surface wave of the lossy conducting medium;   simultaneously exciting a superposed standing wave on the guided surface waveguide probe by exploiting phase delays from transmission line sections of the guided surface waveguide probe plus phase jumps arising from discontinuities in characteristic impedances of the transmission line sections, the superposed standing wave based upon a complex image plane located at a complex depth from a base of the guided surface waveguide probe; and   exciting the charge terminal with an excitation voltage via the transmission line sections, where an excitation charge distribution establishes an electric field that couples into a guided surface-wave waveguide mode along a surface of the lossy conducting medium.