Abstract: A bandpass filter includes a first uniform impedance resonator comprising a first microstrip line and a second microstrip line, a second uniform impedance resonator which is axisymmetric to the first uniform impedance resonators, a first asymmetric stepped-impedance resonator comprising a third microstrip line and a fourth microstrip line, a second asymmetric stepped-impedance resonator which is axisymmetric to the first asymmetric stepped-impedance resonator, a third asymmetric stepped-impedance resonator consisting of a fifth microstrip line and a sixth microstrip line, a fourth asymmetric stepped-impedance resonator which is axisymmetric to the third asymmetric stepped-impedance resonator, a input consisting of a seventh microstrip line and connecting with the first microstrip line, and a output which is axisymmetric to the input and connects with the second uniform impedance resonator.