The earth as most of us know it,
is only a giant ball of rock, soil and water.
Covered with an atmosphere, a few clouds and blue sky. We are unaware
of the restless energy that surrounds us and which vibrates out of sight in the
depths of the earth. Earthquakes..Volcanos..Thunderstorms..signals from
natural events seething in a cauldron of frequencies. Man made signals from
Communication and Broadcast stations, experimental transmitters of many
types, using the ionosphere to echo unseen messages.
All of these signals have one thing
in common. They use a medium for
propagation. The atmosphere and ionosphere above the surface of the earth,
the earth itself beneath the surface. Electromagnetic signals which are generated
by the mentioned causes above, when traveling or propagating through a
medium are limited concerning the distance, due to characteristics of the wave
and the substance through which it travels.
An electromagnetic wave traveling
through free space propagates close to
the velocity of light which is roughly 186000 miles per second. However
the power decreases in inverse proportion to the square of the distance
traveled. In other words if you were to generate a signal that would measure
16 watts at a distance of 1 meter, the signal measured at a distance of 2
meters would only measure 4 watts.
An electromagnetic wave or voltage
traveling through the earth decreases
linearly with the conductance of the material. The earth as a whole is quite
a good conductor therefore with a set value of resistance as an example, at
a power of 16 watts measured at a distance of 2 meters, the signal
measured at 100 meters could be 14 watts. At 200 meters the power would
be 12 watts. At 300 meters..10 watts and so forth.
Because the earth attenuation to
signals is linear rather than in inverse
proportion to the square of the distance, a small signal travels much
further through the earth than the same small signal through the atmosphere.
There are many types of signals
passing below us consisting of an uncountable
number of frequencies. Generally the lower the frequency and the longer the
wavelength, the further a signal will travel. It is known that various
Government agencies have used low frequency communication for decades
because of the ability to penetrate depths and salt water. Submarine
communication is an example.
The signals which we hope to bring
to your attention are much lower in
frequency than those which are commonly used. We will show those of
you who are interested, how to build these receivers so that you may
satisfy your curiosity and perhaps even to join in the research of this
vastly unexplored underworld.