Design of BPF using Zeland IE3D

Hi,,,
When I design a filter , as i specify the band pass filter parameters, the sim. results show another pass band to the desired one? It is look like as repeating the pass band ? (after 13.8GHz, see the fig.) do u konw why and how to stop other bands ?( just desired pass band)
help.

thankx

it ia due the fact that the transmission lines are periodic in thier properties , so the microstrip filter will aslo be the same

khouly

Hi,,,
could u explain more , plz
thankx alot