This section describes the basic operating principles of strip line junction circulators and isolators. The following information has been compiled from many technical papers. It has been summarized to present a simplified non-mathematical description that is used to highlight the operating characteristics of various circulator and isolator types. Although this paper is not intended to be a design guide it is hoped that the information presented will be useful to both the buyer and system engineers. A junction circulator is a 3-port device formed by a symmetrical Y-Junction strip line coupled to a magnetically biased ferrite material. When one of the ports is terminated, with either an internal or external termination, the device then becomes an isolator which isolates the incident and reflected signals.