Compact broadband quadrature hybrid coupler using planar artificial transmission line

A novel compact size broadband quadrature hybrid coupler based on a planar artificial transmission line which can be used for WLAN application at 2.4 GHz is presented. The planar artificial transmission line is composed with both a dual transmission line and the π-model technique. The occupied size of the proposed broadband hybrid coupler is merely 47 of the size of a conventional design. The compact size coupler demonstrates well-behaved wideband response and good agreement with measurement.