A novel magnetic-free broadband circulator based on three switched delay lines

A novel magnetic-free circulator is designed based on three switched delay lines with a total electrical length of 180-degree at the switching frequency. The transmission and reflection characteristics of the circulator were investigated, and the calculation and simulation results show that the proposed magnetic-free non-reciprocal structure can work in a broadband. A prototype circuit was fabricated. In the frequency range of 300kHz-100MHz, the measurement shows that the reflection loss and isolation are more than 15 dB and 20 dB, and the insertion loss is less that 4 dB, respectively.