Abstract:A method obtaining broad-band EGB(Electromagnetic Band-Gap) Structure is studied in this paper. The simulated results show that the band-width of band-gap is enlarged using method of changing period linearly, and the smoothness of pass band and band-gap are imprved using techniques of windowing unit’s size. For the example presented in this paper, -20dB bandwithd of band-gap is increased by 20%, and the insertion loss is less than 04dB for pass-band below 3GHz. Several circuits are manufactured, and the measured results are basically accordant to simulated results.