Abstract: This paper analyzes ripples in pass-bands of series loaded Electromagnetic Bandgap(EBG) band-stop filters.The effects of capacitor,inductor and parallel resonance on ripple are compared.An EBG band-stop filter with low ripples in pass-bands has been designed and fabricated as well.The filter has 4 periods.And it is realized by etching spiral slots on the ground of a microstrip.The filter has a center frequency of 2.44GHz.Its attenuation at stop-band center is more than 50dB,while ripples in adjacent pass-bands are less than 0.29dB.The coincident results of simulation and measurement validate the analysis and design.