A brief history of wireless technology

I occasionally end seminars that I conduct on various wireless topics by saying, "Show me another area of high tech, especially one this old, where there's this much innovation going on - I don't think you can." But just how old is wireless technology, anyway? Most people are surprised to find that it goes back well over 200 years.

If we ignore optics, which fascinated early scientists over two thousand years ago, one might argue that the long trail of innovations that have brought us to the fast, cheap, and (mostly) reliable wireless products and services of today in fact began with Benjamin Franklin and his famous kite. It is very unlikely that Franklin actually conducted the experiment as it is often described, with keys tied to a kite string - had he done so, he might never have survived to sign the Declaration of Independence! But Franklin did, in 1747, propose a model of electricity that proved surprising correct. And at that point it was evident that electricity could in fact move through the air.

In 1819, the Danish physicist Hans Christian Oersted noted that a compass needle would move in the presence of an electric field, thus establishing the fundamental relationship between electricity and magnetism. We call the entire field electromagnetics to this day.

In 1831, Michael Faraday demonstrated electromagnetic induction and built the first direct-current generator. While this wasn't useful for wireless communications, it did provide a way to generate electricity.

The next big leap forward was the result of theoretical work by James Clerk Maxwell, the great Scottish physicist. He published "On a Dynamical Theory of the Electromagnetic Field" in 1865, and in 1873 "A Treatise on Electricity and Magnetism," which became what are known Maxwell's Equations. These are a series of very difficult differential equations which describe the movement of electromagnetic waves through space. Remarkably, we use them to this day. I'm always amazed that someone working in a cold, damp building in Scotland, with little in the way of computational technology and probably nothing more than an oil lamp for light, devised something so fundamental and powerful that we still use it. Maxwell, by the way, had never seen a radio; they did not exist then, and he had no actual experience with radio waves themselves. But the theory he developed paved the way for the next set of critical inventions.

Building on Maxwell's work, Heinrich Hertz in 1887 invented the oscillator (an alternating-current generator) and created radio waves. By the way, this is the Hertz of megahertz and gigahertz, not the rental-car company. I should also note that Oersted, Faraday, and Maxwell all had units of physical measurement named in their honor as well.

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