A coupled line type of Wilkinson power divider with flexible bandwidth and out‐of‐band rejection performance

In this letter, a coupled line type of Wilkinson power divider (PD) composed of series transmission lines and coupled lines is proposed. By employing 2 pairs of transmission lines, the difference between the even‐/odd‐mode impedance of the utilized coupled line can be controlled; hence the performance of the bandwidth and out‐of‐band rejection can be changed simultaneously. Detailed design equations are derived and can be easily applied in future works. Due to the inherent bandpass characteristic of the coupled line, DC block is achieved simultaneously. For experimental purpose, a prototype PD with a center frequency of 2.5 GHz is simulated and fabricated, and the measured results show a good agreement with theoretical analysis.