Compact power divider for wideband in‐phase and out‐of‐phase performances using parallel coupled lines

A novel structure that can operate as an in‐phase and out‐of‐phase power divider across 100% fractional bandwidth is presented. The proposed structure adopts two pairs of parallel‐coupled lines to enable changing the operation from in‐phase to out‐of‐phase while improving the return loss and isolation of a traditional Wilkinson power divider. Moreover, the device includes a stepped impedance T‐junction for input port impedance matching. Changing the status of two terminals of one pair of coupled lines from open‐ended to short‐ended allows achieving changing the operation from in‐phase to out‐of‐phase performance. Using a chip capacitor between the coupled lines enables realising the needed tight coupling without the need to have narrow gaps. A prototype is fabricated and measured. Simulated and measured results show more than 10 dB of return loss and more than 15 dB of isolation across the investigated band 1–3 GHz. In addition, the device provides less than 1 degree phase imbalance and 0.2 dB amplitude imbalance in the in‐phase and out‐of‐phase states across the whole frequency band.