The document discusses different methods of wireless transmission across the electromagnetic spectrum. It covers radio transmission, which can travel long distances but power falls off with distance; microwave transmission, which travels in straight lines and is used for long-distance communication; and infrared transmission, which is used for short-range communication like TV remotes but does not pass through objects well. It also mentions lightwave transmission using lasers offers high bandwidth but requires precise aiming over distance.

1. Wireless Transmission By Sabarathinam

3. The Electromagnetic Spectrum f (Hz) 10 4 10 5 10 6 10 7 10 8 10 9 10 10 10 11 10 12 10 13 10 14 10 15 10 16 L: low M: medium H: high V: very U: ultra S: super E: extremely T: tremendously f (Hz) 10 0 10 2 10 4 10 6 10 8 10 10 10 12 10 14 10 16 10 18 10 20 10 22 10 24 Visible Light Radio Microwave Infrared UV X-ray Gamma Ray Twisted Pair Coax Maritine AM Radio FM Radio TV Satellite Terrestrial Microwave Fiber Optics HF EHF LF MF VHF UHF SHF THF Band

6. Propagation of Radio Waves VLF, LF, and MF bands Ionosphere HF and VHF bands Earth Earth Radio waves follow the ground