A microstrip dual-band crossover with asymmetrical transmission lines

A microstrip crossover with dual passbands is proposed. With the asymmetrical n-shaped transmission lines inserted into the window-shaped crossover, a wide and flexible operating frequency ratio can be obtained. Consequently, the even- and odd-mode analysis and the fourfold symmetry are adopted to derive the design equations. In order to validate the proposed structure, a crossover with a compact size, 0.38λ_g × 0.38 λ_g is fabricated.