Design and Testing of a Single-Layer Microstrip Ultrawideband 90° Differential Phase Shifter

This letter proposes a design of single-layer microstrip ultrawideband (UWB) 90^° differential phase shifter. The operating bandwidth covers the UWB frequency range from 3.1-10.6 GHz. The design is optimized using a transmission line model and an electromagnetic model, and have been fabricated using a plotter dealing with generation of printed circuits. The measured <i>S</i>₁₁ is better than -10 dB and <i>S</i>₂₁ is better than -0.96 dB within the UWB frequency range. The simulated and measured phase deviation of the differential phase shift are 90^°±5.23^° and 90^°±9.02^°, respectively. The advantages of the proposed design are the simple fabrication, low insertion loss, and broad bandwidth.