Radiation Patterns
Michael T. Chryssomallis, Christos George Christodoulou · Encyclopedia of RF and Microwave Engineering · 2024
Abstract The radiation pattern of an antenna is one of its basic properties since it shows the way the antenna distributes its energy in space. It generally consists of a number of lobes, and if it is measured far away from the antenna, it is independent of distance. It is a function of angles and can be expressed as field or power pattern. It usually can be completely specified from the patterns in two planes, perpendicular to each other, the E ‐ and H ‐plane, respectively. Related to the radiation pattern of an antenna, a number of important parameters exist, such as radiation power density, beamwidth, radiation and beam efficiency, directivity, gain, and antenna polarization. The subject of this article is to provide an introduction to radiation patterns and all the related important parameters. The content is organized in four sections. The first section introduces several antenna patterns, giving the necessary definitions and presenting the common types. The field regions of an antenna are also pointed out. In the second section, after the introduction of Poynting vector and radiation power density, radiation performance measures such as the beam solid angle, directivity, and gain of an antenna are defined. In the third section, the concepts of wave and antenna polarization are discussed. Finally, in the fourth section, a general case of antenna pattern calculation is considered, and numerical solutions are suggested for radiation patterns that are not available in simple closed‐form expressions.