Tesla's Earth Resonance

 dwp> The DR Corum I met was a PhD in Emag. A Radio Engineer, of
 dwp> the higher level. I do not recall his comments on how       
 dwp> closely the earth is modelled by "perfectly conducting".

Which is why I always try to provide references, or, why I am
always prepared to name references.

I am quoting out of my copy of: PROCEEDINGS of the 1988
INTERNATIONAL TESLA SYMPOSIUM, 1988, edited by Steven R. Elswick,
BSEE, Mem.IEEE, published by the International Tesla Society,
ISBN 0-9620394-2-X, chapter 3, pp1-16, "Concerning Cavity Q"
James F. Corum, Ph.D., Kenneth L. Corum, Craig Spaniol, PhD, PE.

  "In this note we discuss the issue of low Q for the Schumann    
  cavity and its effect on global power distribution. We deter-   
  mined that the observed Q is attributable to shunt atmospheric
  conductivity, and as such is equivalent to the excitation loss
  of conventional power transformers. We conclude that low Q is
  not an issue of substance for global power distribution in      
  Tesla's system."

To accurately paraphrase, they included excitation and resistance
losses and determined that even though the earth is far from
"perfectly conducting" it conducts resonate current rather well.

  "We suggest that Tesla, although he was one of the pioneers of
  distributed tuned resonance and was here dealing with a cavity
  resonator, would have approached the terrestial resonator from 
  a power engineer's perspective. As with the power transformers
  and distribution elements of his 60 Hertz system, Tesla would
  have wanted to determine both the propagation and the equi-     
  valent shunt losses of the terrestrial resonator system. As a
  power engineer, the Colorado Springs ELF experiments led him to
  conclude that both are inconsequential."

Remember that Tesla designed the 60 cycle power grid, and never
backed down from his statement that the worldwide wireless system
was even more efficient. Corum, Corum and Spaniol concluded that
the more power pumped through the wireless system the better. The 
calculated losses remain rather constant regardless of the amount
of power conducted.

In a later paper (same reference, Chapter 3, pp17-23) John F.
Sutton (Goddard Space Flight Center) and Dr. Spaniol (referenced
above): " A Measurement of the Magnetic Earth-Ionosphere Cavity
Resonances in the 3 - 30 Hz. Range " 

  "It is a common complaint that low cavity Q's imply that one of
  Tesla's greatest schemes, wireless transmission of power on a
  global scale, would be impractical. In their paper [see above]
  "Concerning Cavity Q," Corum, Corum, and Spaniol point out that 
  low cavity Q's do not necessarily limit the practicality of     
  such a system. Our current measurements indicate that the       
  cavity Q's are one or two orders of magnitude higher than       
  previously estimated and therefore would not be a limitation
  in any case."

I should mention: These cavity Q measurements include the
resistance of the conductor (earth) at the frequency measured.
Dr. Spaniol was using very good equipment (able to detect
lightning strikes on the far side of the planet). One problem
with Schumann's measurements of the 1950's, and Rycroft's
measurements of the 1960's was the low resolution of the
available detection equipment at these ELF and VLF frequencies.
Dr. Spaniol states that using Rycroft's scope (sweep frequency
analyzer) it was impossible to measure a Q factor above 8 at a
resonate frequency of 8 Hertz. Want some hard numbers?

  "Figures 6 and 7 are plots of resonances at 25.00 Hz and 35.96
  Hz, respectively, both with Q's of approximately 600. Figure 8
  is a plot of an 8.4 Hz cavity resonance response with a Q of at
  least 100. Figure 9 is a cavity response at 19 Hz just resolved
  above the noise level. It has a Q of at least 1,000."