Akindofdual-band-stopfilterwithanunsymmetricalT-shapedefectedgroundstructure(DGS)isproposed.Thefilterhastwobandgapcentersat4.9GHzand7.35GHz,respectively,wherethetwocentrefrequenciesarejustthesecondandthirdharmonics2.45GHz.Thefilterswithhighband-stopperformanceandwidebandspurioussuppressioncanbeachievedbycascadingminiaturizedunsymmetricalT-shapeDGS.Theattenuationofthree-cascadedT-shapeDGSfilteris30.77dBat4.9GHzand17.96dBat7.35GHzrespectively.Theaboveexperimentalresultsareingoodagreementwiththesimulationresults,especiallyforthethirdharmonic.
