Interdigitated Strip-Line Quadrature Hybrid

Hybrids are frequently used as components in microwave systems or sub-systems such as balanced mixers, balanced amplifiers, phase shifters, attenuators, modulators, discriminators, measurement bridges, etc. An ideal hybrid is a four-port junction with properties such that a wave incident in port one couples equal power into ports two and four but none into port three. Hybrids are classified according to the phase shift between the two outputs. There are two basic types: 180° hybrids and 90° (quadrature) hybrids. The latter are also called 3-dB directional couplers.