The universe is composed of an infinite number of frequencies. Some macroscopically large and some microscopically small. All exist in uncountable phase relationships with one another.
The colors of light, the sound of music, the smell of flowers, the touch of velvet, all are made of combined frequencies. Some are in phase and adding to, some are out of phase and cancel from, a multitude of vibrations.
Our five senses are capable of interpreting these particular waves and making them tangible to our perception.
Beyond these senses, most of us have to rely on artificial means to convert these frequencies to the range of our comprehension. We can build devices to generate and detect Radio and Television broadcasts, construct X-Ray machines, and design Ion Propulsion Generators to power space probes. We can detect distant Galaxies light years away. The wavelength of a vibration is inversely proportional to the frequency. For instance, an AM Radio Station operating at 1000 kHz (1,000,000 Hz) on the dial, radiates an electromagnetic wave which has a wavelength of 299.82 meters. The power line frequency in your house if you live in the US is 60hz. The wavelength at this frequency is 4997000 meters or 3104 miles. The lower the frequency the longer the wavelength. Lets turn now in another direction
There is another frequency spectrum that is almost unexplored and unknown. And it can be found underneath your feet.
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.