A novel circular grooved and ridged waveguide phase shifter with dielectric‐loading is proposed, fabricated, and discussed in this article. Both experimental and numerical results obtained show that the proposed circular grooved and ridged waveguide phase shifter, when compared with the conventional one, has larger differential phase shift, smaller length, and no obviously changed insertion loss. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2793–2795, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22878