Fig. 1. Transformer voltage ratio transformation diagram

Fig. 2. Diagram of a transformer with a voltage transformation ratio of 3∶2

Fig. 3. Diagram of 1∶2.25 balun circuit structure

Fig. 4. Curve of ferrite toroid magnetic permeability variation with frequency

Fig. 5. Dimensions of the balun

Fig. 6. Photo of the balun

Fig. 7. Simulation and measurement results of the balun’s input port VSWR

Fig. 8. Simulation and measurement results of phase and amplitude imbalance

Fig. 9. Comparison of S-parameters at different feed power in balun

Fig. 10. Comparison of output imbalance at different feed power in balun