Fascinating history of wireless communications, with lots of info and schematics to try reating your DIY wireless communication system on Ashish’s Programming Journal:
In this modern age of high tech gadgets, it is easy to take the technology around us for granted. If we look at the world around us as if we have never seen it before, it would be impossible not to be filled with awe and wonder. In this article, I will tell you the story behind one of the most important technological inventions of modern times – wireless communication. I will also describe some of my own experiments with high voltage spark transmitters and coherers!
Many years ago, when there were no cell phones or Internet, a great scientist by the name of Michael Faraday speculated the existence of electromagnetic waves when he observed the influence of magnetic fields on polarized light (Faraday Effect).
Years later, David Edward Hughes (an Anglo-American concertina player and inventor) observed something very bizarre. When working on his Induction Balance, a loose contact was creating sparks. Hughes noticed that a telephone circuit connected to his carbon microphone on the other side of the room was somehow picking up that noise. He took the telephone circuit outside, and he could still hear the clicks made from the induction coil up to 500 yards away! You could consider this the first mobile phone call in history!
In the 1880s, physicist Heinrich Hertz was trying to confirm the existence of Maxwell’s electromagnetic waves. After observing induced sparking in a Riess spiral, Hertz concluded that this phenomenon could be used to detect the waves. He set up a spark gap transmitter, and a receiver.Around the same time, a scientist named Oliver Lodge was investigating some issues with lightning rods. To simulate lightning, he was using two Leyden jars to create high voltage sparks.