Multisection branch line couplers as dual-band crossovers using coupled lines for wideband applications

This article presents multisection branch line couplers as dual-band crossovers using coupled lines (CLs) for wide bandwidth (BW) applications. The efficiency of the CL as a dual-band impedance transformer and its closed form design equations has also been explored. Specifically, dual-band crossovers having three and four sections have been designed using the advanced design system software and then implemented on a Rogers 5870 substrate with a dielectric constant of 2.33 and thickness of 0.787mm. The designs have been developed for 1 and 2.6 GHz operating frequency bands. A much wider BW and interband suppression, of 225/218MHz and 86.45% for the three-section prototype and 269/260MHz and 85% for the four-section prototype respectively, have been achieved. It is concluded that the proposed crossovers exhibited a much wider BW as compared to the existing dual-band crossovers.