Electromagnetics Explained

5 RADIATION

Every person, whether technical or nontechnical, is quite familiar with electromagnetic radiation. We directly experience radiation as light and heat radiation, and we also rely on radio, TV, cell phones, and other devices that make use of this property of nature. But what is electromagnetic radiation and how is it produced? How is radiation different from the static fields we find around a charged object or permanent magnet? Intuitively we know that radiating fields are far-reaching, whereas nonradiating fields like those of a refrigerator magnet are concentrated near their source. This intuitive notion is a good start for learning the details.

Understanding antennas and electromagnetic radiation is obviously important in RF engineering, ...