An adjustable output power ratio general type branch line coupler

An adjustable output power ratio branch line coupler design is proposed. The mixed transmission line and shunted capacitor T-type equivalent circuit replaced the arms of the general branch line forms the tuning mechanism. By changing the shunted capacitors values, the power at output ports could shift to the desired ratio. A prototype circuit designed at 925MHz has been simulated and fabricated on FR4 substrate. The simulated experimental results show that the output power ratio changing is in a good agreement at the design frequency.