Radiation

This chapter discusses radiation from circuit boards, transmission lines, conductor loops, and antennas. It presents the frequency spectrum of square waves and pulses. Matching of impedances is required to move energy from a transmission line into an antenna so that it can radiate this energy into free space. The chapter considers common‐mode and normal‐mode coupling of fields to conductors and the concept of wave impedance and its relation to shielding. Interference can be analyzed by using a rise‐time frequency to represent pulses or step functions. Effective radiated power from various transmitters is presented. The chapter also discusses the field intensities for lightning and electrostatic discharge (ESD). Loops generate low‐impedance fields that are often difficult to shield. The chapter suggests some simple tools for locating sources of radiation. A very practical tool to measure the magnetic fields near apertures or conductors can be built using a section of coaxial cable.