Compact and wideband 180° hybrid using vertically coupled CPW balun with lumped elements

A new compact and wideband 180° hybrid is proposed. The proposed structure stems from the idea of converting a balun into a 180° hybrid by adding an in-phase power divider. In order to achieve wide bandwidth and miniaturized size, a lumped power divider and a vertically coupled CPW balun with lumped elements are used. For verification, the proposed 180° hybrid is designed at 917 MHz. The measurement shows that the bandwidth of CMRR greater than 25 dB is increased by 84 % compared with that of the conventional ring hybrid.