Quadrature Coupler with Enhanced Coupling Bandwidth and DC Isolation for C-Band Applications

This paper presents an alternate design for a conventional 3dB Branch line coupler (Quadrature Coupler) for C Band applications. The proposed coupler is designed for 5.2GHz. The proposed coupler has parallel-coupled lines at the port of conventional 3dB coupler with slotted ground plane. The novel design of the coupler allows 82.6% of bandwidth improvement with DC(Direct Current) isolation. The designs have been simulated and fabricated on FR4 dielectric substrate and measured using Vector Network Analyzer. Simulated and fabricated results of the S-parameters are presented.