A novel design of planar dual-band microstrip crossover operating at small and large frequency ratios is presented. These features of the proposed dual-band crossover are achieved by a cross-shaped transmission line. To obtain the dual-band characteristics, the required closed form design formulas are computed using the ABCD matrix method. Based on the design formulas, the realizable small and large band ratios are calculated as 1.65–2.14 and 4.1–8.76, respectively. To validate the computed band ratios, three examples of dual-band crossovers are presented. Finally, two prototypes of dual-band crossover working at smaller and larger frequency ratios are fabricated and tested. The fabricated dual-band crossovers exhibit good return loss and isolation of over 20 dB with minimal insertion loss.
A novel design approach to the miniaturization of dual-band branch-line coupler
