Devices for passive circuits
Passive microwave circuits - Non-reciprocal ferrite elements

In this final section, we present a number of devices that are widely used in microwave applications in radio, telecommunications and radar technology. These devices are sub-systems that combine several of the elements - couplers, magic tees, circulators, filters, cavities - that we have studied in previous articles. , , and . In this way, they can perform essential functions such as duplexing, multiplexing and diplexing.

Radiating source feed networks that combine directional couplers and phase shifters in an interesting way will not be considered here. However, readers are invited to consult the articles on antennas. , , and .