Tesla moves to research facility in Colorado Springs
In 1899, Tesla decided to move and began research in Colorado Springs, Colorado, where he would have room for his high-voltage, high-frequency experiments.
Upon his arrival he told reporters that he was conducting wireless telegraphy experiments transmitting signals from Pikes Peak to Paris. Tesla's diary contains explanations of his experiments concerning the ionosphere and the ground's telluric currents via transverse waves and longitudinal waves. At his lab, Tesla proved that the earth was a conductor, and he produced artificial lightning (with discharges consisting of millions of volts, and up to 135 feet long). Tesla also investigated atmospheric electricity, observing lightning signals via his receivers. Reproductions of Tesla's receivers and coherer circuits show an unpredicted level of complexity (e.g., distributed high-Q helical resonators, radio frequency feedback, crude heterodyne effects, and regeneration techniques). Tesla stated that he observed stationary waves during this time.
Tesla researched ways to transmit power and energy wirelessly over long distances (via transverse waves, to a lesser extent, and, more readily, longitudinal waves). He transmitted extremely low frequencies through the ground as well as between the Earth's surface and the Kennelly–Heaviside layer. He received patents on wireless transceivers that developed standing waves by this method. In his experiments, he made mathematical calculations and computations based on his experiments and discovered that the resonant frequency of the Earth was approximately 8 hertz (Hz). In the 1950s, researchers confirmed that the resonant frequency of the Earth's ionospheric cavity was in this range (later named the Schumann resonance).
In Colorado, Tesla carried out various long distance power transmission experiments. Tesla effect is the application of a type of electrical conduction (that is, the movement of energy through space and matter; not just the production of voltage across a conductor). Through longitudinal waves, Tesla transferred energy to receiving devices. He sent electrostatic forces through natural media across a conductor situated in the changing magnetic flux and transferred power to a conducting receiving device (such as Tesla's wireless bulbs).
In the Colorado Springs lab, Tesla observed unusual signals that he later thought may have been evidence of extraterrestrial radio communications coming from Venus or Mars. He noticed repetitive signals from his receiver which were substantially different from the signals he had noted from storms and earth noise. Specifically, he later recalled that the signals appeared in groups of one, two, three, and four clicks together. Tesla had mentioned that he thought his inventions could be used to talk with other planets. There have even been claims that he invented a "Teslascope" for just such a purpose. It is debatable what type of signals Tesla received or whether he picked up anything at all. Research has suggested that Tesla may have had a misunderstanding of the new technology he was working with, or that the signals Tesla observed may have simply been an observation of a non-terrestrial natural radio source such as the Jovian plasma torus signals.
Tesla left Colorado Springs on 7 January 1900. The lab was torn down and its contents sold to pay debts. The Colorado experiments prepared Tesla for his next project, the establishment of a wireless power transmission facility that would be known as Wardenclyffe. Tesla was granted U.S. Patent 685,012 for the means of increasing the intensity of electrical oscillations.