Antennas and Radiation

This chapter discusses the fundamental operation of a general antenna structure, independent of its specific configuration and application, and device basic performance parameters commonly used in antenna technology. Specifically, this discussion analyzes basic antenna parameters under four operating conditions: (1) antenna as a transmitter, (2) antenna as a receiver, (3) antenna in a transmit-receive communication link, and (4) antenna as a scatterer. An antenna is a device used for transmission or reception of electromagnetic waves, allowing radio-frequency communication between distant locations across empty space or other material media. Antennas are fabricated using conducting materials, which are designed with desirable radiation or reception characteristics, and employ suitable coupling arrangements to an external port for an input/output (I/O) connection. The I/O may be used for exciting the antenna from a radio-frequency signal source or for coupling any radio-frequency signal received by the antenna to an output load, respectively, when operated as a transmitter or a receiver.