A novel balanced circulator for FDD MC-CDMA communications

This paper presents a new balanced circulator with improved isolation. It uses hybrid couplers to compensate the isolation fault of two standard circulators. A 800 MHz banduidth (14.55 %) for 30 dB isolation has been measured at 5.5 GHz with a first prototype using standard microstrip technology and two standard ferrite circulators (with a 20 dB isolation). An integrated implementation including microstrip antennas is also proposed that exhibits diversity capabilities.