Nikola Tesla - Electric Echo

"There is no doubt that wireless communication anywhere on the globe is possible and I have proved it. Here is how we can, with the utmost simplicity, explain this phenomenon: when we raise our voice and get an echo, we know that the The sound emitted collided with a wall or other obstacle, which sent it back to us. The electric wave reflects in the same way as the sound. Instead of sending sound vibrations towards a distant obstacle, I sent electric vibrations towards the ends of the earth envelope and, like the obstacle in the case of the sound wave, they themselves returned the vibrations. In place of the echo, I obtained a stationary electric wave, reflected and sent back from far away “.——Nikola Tesla, Colorado Springs, 1899