AbstractA novel bandstop filter using star shape structure is designed, fabricated, and measured. Parameters are optimized via numerical simulations. Measurements are carried out using network analyzer. The proposed filter has wide bandwidth, compact dimensions, easy fabrication, and low cost. The simulated and measured results show that the 3 dB bandwidth of the bandstop filter is from 2.2 to 5.0 GHz the least insertion loss of 0.1 dB, and the largest stop‐band attenuation is of −45 dB. There is a good agreement between the simulated and experimental results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2464–2466, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24624