On the left handed ferrite circulator

Left handed (LH) ferrite circulators composed of the nonreciprocal LH microsrtip lines using perpendicularly magnetized ferrite substrate and operating at the negative permeability frequency are studied. Following three types of circulators are proposed: a disk shaped circulator having broadband characteristics and high insertion loss, a triangular shaped circulator having small insertion loss and narrowband characteristics, and a ferrite-coupled-line LH circulator having wideband characteristics and high isolation. Although each structure has a advantage of circulator operation, the ferrite-coupled-line LH circulator has a potential for new signal processing functions of signal flow of backward characteristics.