http://en.wikipedia.org/wiki/Extremely_low_frequency said:
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As used in military applications, the wavelength is ~299,792 km(~187,370 mi) per second divided by 50–85 Hz, which equals around 3,450 to 5,996 km (2,140 to 3,726 mi) long; by comparison, Earth's diameter varies from 12,715 km (7,901 mi), pole to pole to 12,756 km (7,926 mi), equatorial. Because of this huge size requirement and, to transmit internationally using ELF frequencies, the earth itself must be used as an antenna, with extremely long leads going into the ground. Various other means are taken to construct radio stations with substantially smaller sizes, such as electrical lengthening
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Ah, electrical lengthing... yes I have actually seen these systems,
so that means the above penetration distances are much, much
deeper? The real facts are most likely classified... but in any case,
this is for sub-surface penetration and in the mean time, don't forget
the satellites... As above, so below...
I learned a long time ago that masers and lasers go hand in hand -
masers blow open a long distance channel trough a medium (air.
water, ...), and lasers are fired from within. Why?
Because lasers quickly lose energy through the atmosphere, but
inside a maser, lasers delivers a full power punch? Did you not notice
in ID4, the one-two maser/laser punch delivered from the saucers?
Perhaps, VLF/ELF could be used similar to a maser - to carry certain
"payloads" over great distances through several mediums?
The same principle is also applied in fiber-optics - two or more doped
glass sheaths (multi-mediums), one within another so as to carry primary
signals with negligible loss over long distances...
FWIW,
Dan