The Earth-Moon-Earth (EME) Communications in which Ham Radio Signal sent straight up to Moon using directional antenna making using of the moon as a passive reflector and thus some part of the radiating signal reflects back to the earth that makes it possible to have long-distance communication.
Presentation covers radio technology development from the Maxwell's mathematical description of electromagnetic waves in 1860-1865, Hertz's development of a crude spark transmitter and spark receiver that proved the existence electromagnetic waves in 1886-1888