Micro-strip line based compact wideband branch-line coupler lumped distributed element transformations

This paper deals with the design of a compact wideband branch-line coupler in micro-strip lines technology intended for the reduction of radio frequency front ends size. The compact coupler is developed using conventional analysis followed by successive lumped distributed element circuit transformations. With a lower frequency of 2.14 GHz and an upper frequency of 2.5 GHz (WCDMA and WiMAX communication standards), several coupler prototypes were designed and fabricated to validate the different size reduction iterations.