DOI: 10.1109/TMTT.2025.3645222   IEEEXplore: https://ieeexplore.ieee.org/document/11314767    

Miniaturized four-port single-junction microstrip circulator.

10.58 GHz nominal center frequency

Small size compared to cascaded three-port circulators and excellent performance with low insertion loss compared to ferrite coupled-line-based four-port circulators are achieved with a single junction microstrip four-port circulator. By applying multiple rotation mode (MRM) analysis, the azimuthal characteristics of the internal modes within the cross-resonator and the matching of input impedance can be optimized to realize nearly octave bandwidth performance. A folded transmission circuit constructed by a compact impedance-matching network miniaturizes the circulator.

Wireless transceiver systems with a single antenna to replace cascaded three-port circulators and ferrite four-port circulators in the system with a smaller, higher performance component.

6.85 – 14.3 GHz bandwidth, or 70% relative bandwidth; 1 dB insertion loss S21, better than 17 dB return loss S11 over the bandwidth; 16 dB and 17.8 dB isolation of S31 and S41 respectively over the bandwidth; 11 × 11 mm (0.39λ0 × 0.39λ0) cross-sectional circuit dimensions of the miniaturized circulator.