A Planar Dual 180 $^{\circ}$ Hybrid Using Multicoupled Line Sections

A novel planar dual 180° hybrid using multicoupled line technology is presented. The proposed structure adopts the power divider and two types of multicoupled lines to improve the return loss and isolation at the balance outputs of a traditional dual Marchand balun. The proposed hybrid allows output ports to be located arbitrarily, which eliminates the complex layout while the dual 180° hybrid applied to balanced radio frequency circuits. This hybrid is designed and implemented on an FR-4 printed circuit board at 2.4 GHz. The measured return loss is lower than -19.7 dB, and the isolation between the two-pair balanced output ports are lower than -28.2 dB from 2.2 to 2.7 GHz. The measured insertion loss and phase imbalance between the two-pair balanced output ports are lower than 8.7 dB and 4.5°, respectively, at the operating frequency of 2.1-2.9 GHz.