We designed Stepped Impedance Resonator (SIR) bandstop filter (SIRBSF) with hairpin coupling structures which has good performance and it is compact in size and great advantage having an excellent bandstop property. The center frequency of SIRBSF is 5.1 GHz which is the harmonic of the 2.55GHz band. The 3dB band width of the design is 200MHz with the insertion loss (S21) of 35 dB. The application is used for domestic and international fixed and mobile satellite and mobile communication. The overall size is (10 x 20) mm2.