Chapter 7 - Microwave Components

Abstract

Microwave components differ from lower-frequency components because of the basic physics underlying the phenomena are at a fundamental level. Reactance can be formed of strip line components, by irises in waveguide, and by stubs, posts, or screws in waveguide. Attenuators are devices that absorb power, and thus have a negative gain. Attenuator elements are formed by resistors, conductive vanes in a signal path, or capacitor voltage dividers. A resonant cavity is a metal-walled chamber that contains a region of good dielectric material. Directional couplers are transmission line devices that couple together two circuits in one direction, while providing a great degree of isolation in the opposite direction. An isolator is a unilateral, two-port microwave device. It passes power from input to output with low attenuation, but provides high attenuation to signals from output backward to the input. A circulator is a three or more port device that passes signals in one direction to the next adjacent port. Circulators are often used to couple an antenna to both the receiver, and the transmitter in the same system.