ABSTRACTIn this article, a compact microstrip band‐stop filter with 3–11.2‐GHz bandwidth for ultrawideband applications is proposed. The microstrip filter configuration consists of a transmission line with a pair of C‐shaped strips as a stub, four arc‐shaped slots embedded inside them, and a ground plane. An excellent agreement between measured and simulated results was obtained. The proposed microstrip filter fabricated on a Rogers RT/Duroid 5880 substrate with a relative dielectric constant of 2.2 and has a very small size of 10 × 15 × 0.635 mm3. The proposed filter configuration is simple, easy to fabricate, and can be integrated into any radar system. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:709–711, 2014