Dual-band branch-line coupler with orthogonal coupled branches

In this paper, a novel dual-band branch-line coupler with two orthogonal coupled branches is presented. Explicit design formulas are derived from the even-odd mode analysis. For verification purpose, a dual-band coupler (2.45/5.8GHz) is designed, fabricated and measured. The measured and simulated results are in good agreement with each other. The new dual-band coupler not only exhibits a simple structure with convenient port locations, but also offers design degrees of freedom for alternative implementation.