Basic Wireless Communication for Microcontrollers
Chapter 1 - Electricity and Magnetism
Introduction
Electricity and Magnetism (often called just E&M) is the branch of physics which encompasses the physical aspects of electrical engineering at a very basic level. E&M forms the core of electrical engineering because it is fundamentally electric and magnetic fields which carry information and energy in the circuits and systems we work with.
Since this tutorial assumes that you have a fairly good understanding of electronics, there is a lot of material in this chapter which you may not need. However, in my own study, I have found that there are often a few subtleties in E&M which, if not grasped, will stymie any effort to form a complete understanding of radio communications. With that in mind, it would be good to at least skim this chapter to make sure there aren't any latent gaps in your understanding, even if you are a dyed-in-the-wool electronics engineer or hobbyist.
Like any branch of science, E&M must make certain assumptions. It cannot form concepts from scratch, but instead must rely on forming connections among pre-existing concepts. In this way, it is a little like high school geometry, where you were likely taught certain postulates or unprooven statements. From these all the theorems were dervived. E&M has its own postulates, four of which are very famous and known as Maxwell's Equations.
In this chapter, we will very quickly develop the postulates using a few simple analogies and explanations, and then proceed to show how these postulates yield the electrical and magnetic phenomena which are so delightful and familiar to us EE's. If you are a person who likes to get a really deep understanding of a subject, this will probably be frustrating to you because we cannot possibly fully explore the reasons behind the postulates. Many of these reasons are the subject of modern physics research and what we present here, while correct in its results, is vastly simplified in its explanation. For more about the fascinating topic of why E&M works the way it does, please see the bibliography at the end of this chapter.
This chapter, because it is such a quick review of E&M, is very dense and may be hard to follow in some places. Please bear with me because after all of the material is condensed into just a few postulates, the whole picture should become much clearer and serve as a very useful and reliable tool for understanding radio.
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