Broadband fixed phase shifter for C-band applications

The design of a fixed phase shifter for C-band applications is presented. The proposed device is composed of two parts: a quadrature 3-dB directional coupler and the Wilkinson combiner. The quadrature coupler used in the proposed phase shifter is based on the edge-coupled microstrip lines with a slotted ground plane to make the gap required between the coupled lines feasible. The simulated and measured results of the phase shifter show a 45° ± 5° fixed phase shift across the band 4–8 GHz with less than 1-dB insertion loss and better than 12-dB return loss at the centre of the C-band. The designed device also shows a flat group delay, which enables its use in a narrow pulse transmission/reception and in the high data rate systems. The designed phase shifter has a compact size with dimensions of 30 mm × 30 mm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 396–399, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23133