Analysis and Modelling of Magnetic-free Broadband Circulator Based on Three Switched Reflection Delay Lines

Dawei Tang¹, Qianyin Xiang*¹, Dengyao Tian¹, Mingye Fu¹, Xiaoguo Huang², Quanyuan Feng¹

1. School of Information Science and Technology, Southwest Jiaotong University, Chengdu 611756 , China

2. China Electronic Technology Group Corporation No. 36 Institute, Jiaxing 314033, China

Abstract: Magnetic-free broadband circulator structure based on three switched reflection type delay lines with a total electrical length of 180-degree at the switching frequency is investigated. The nonreciprocal transmission property is modelled and simulated, the impedance mismatching property and reconfigurable direction are studied. A prototype magnetic-free circulator circuit is designed and fabricated using coaxial cables and switches driving by switching frequency of 7.94MHz with tolerance of ±10%. The nonreciprocal scatter parameters are measured in 300kHz ~ 100MHz. It shows that the circulator direction can be reconfigured by changing the switching frequency, and the maximum operating bandwidth equals 1.5f_s which is limited by clock feedthrough and spectrum aliasing.

Keywords: Nonreciprocity; circulator; switched delay line; magnetic-free