Planar Ferrite Isolator Combining Edge-Guided Mode and Gyro-Resonance Absorption

We present a planar microstrip ferrite isolator that utilizes both the phenomenon of edge-guided propagation and that of absorption due to gyromagnetic resonance. Nonreciprocal transmission is realized through asymmetric stub perturbations, eliminating the need for lossy absorbers or shorted strips and enabling compact, low-cost fabrication. Full-wave simulations and measurements confirm low insertion losses of less than 0.9 dB, combined with isolation and reflection coefficients greater than 20 dB over a fractional bandwidth of approximately 11%. Compared to conventional edge-guided or resonance-based designs, the proposed hybrid approach improves backward-to-forward loss ratio while maintaining a simple planar implementation, providing a practical path toward highly performance, integrable nonreciprocal microwave components.