Performance of stripline-type ferrite coupled line circulators

Abstract

The normal-mode approach is used to design stripline-type ferrite coupled line circulators with alumina as a substrate and ferrite as a superstrate. The measurements that are taken clearly demonstrate the nonreciprocal behavior of these devices, with an average insertion loss of 5 dB and an isolation of −12 dB. It is found that the three-port circulator has a broader bandwidth (9–14 GHz) than that of the four-port circulator (9–12 GHz), and the hybrid coupler has been identified as the bottleneck in the latter. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 173–179, 2003.