A waveguide phase shifter with good flatness and broad bandwidth

In this paper, a novel waveguide 90° phase shifter with good flatness and bandwidth is designed. This structure is achieved by a E-plane stub-load rectangular waveguide and a step waveguide with the same length. According to this design, we achieves a relative bandwidth 21% for return loss lower than −20dB and phase imbalance within ±0.6°and insertion loss about 0.05dB.