In this paper, a new method is introduced to design a simple-profile hybrid coupler in two arbitrary frequency bands. The structure is achieved by means of dual-band quarter-wavelength transformers as the arms of a traditional branch line coupler. A prototype of the coupler operating at 0.9 GHz and 2.45 GHz is designed and fabricated to validate the robustness of the method. Comparing simulated with measured results, a good agreement is observed. Moreover, the performance of the coupler in terms of impedance bandwidth and isolation level between the input ports is compared with existing works. Further, the suggested coupler has the simplest profile resulting from the most flexible design process.
Guy A. E. Vandenbosch,
"A Low-Profile Dual-Band Hybrid Coupler with Flexible Frequency Band Ratio," Progress In Electromagnetics Research Letters,
Vol. 107, 119-124, 2022. doi:10.2528/PIERL22092903
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