Wireless Power Through the Upper Air: Tesla's 1900 Patent (U.S. 645,576)

2 minute read. Published October 17, 2026.

In short: U.S. Patent No. 645,576, System of Transmission of Electrical Energy, was granted to Nikola Tesla on March 20, 1900. It describes a transmitter and a receiver, each with a tall, elevated terminal, designed to pass electrical energy between them through the rarefied air of the upper atmosphere instead of through wires.

Tesla's 1900 wireless power patent drawing printed in amber on a black T-shirt — FIG. 1 from U.S. Patent 645,576, restored and printed in amber on black.

What did the patent propose?

Tesla reasoned that air at very low pressure, high above the ground, becomes able to conduct electricity when exposed to extremely high voltages. If a transmitting station could raise a terminal high enough and charge it to an enormous voltage, the thin air above could act as one half of a circuit, with the earth as the other. A matching receiver, built the same way, would collect the energy at a distance.

How did Tesla test the idea?

In 1899, Tesla built an experimental laboratory in Colorado Springs, Colorado, chosen in part for its high altitude. There he worked with powerful high-voltage oscillators, producing artificial lightning, while investigating how electrical energy might travel through the air and the ground.

Why does this patent matter?

It's one of the clearest statements of Tesla's ambition: not just wireless messages, but wireless power. That ambition led directly to Wardenclyffe Tower on Long Island. The specific method in this patent never became a practical power system, but the dream of energy without wires still drives research today.

What does the drawing show?

FIG. 1 lays out the two stations side by side: tall vertical conductors rising to large rounded terminals, with coils and connections at their base. Its symmetry is what makes it such a striking piece of design.