Wideband 3-dB coupler using a patterned ground plane

A novel wideband tandem 3-dB coupler using a patterned ground plane is presented in this paper. In this new design, with the ground plane under the coupled lines removed, the even-mode capacitance will be decreased substantially. Meanwhile, two additional separated rectangular conductors are placed under the coupled lines to act as two capacitors so that the odd-mode capacitance is increased. As such, a well-designed 3-dB coupler on a double-sided PCB is achieved. The proposed new design was simulated and validated by the measurement.