Abstract: A filter configuration including a substrate, a primary microstrip line and a first defected ground structure is disclosed. The substrate has a first face and a second face. The second face is a ground face. The primary microstrip line is arranged on the first face and extends in a first direction. The first defected ground structure is arranged on the second face. The first defected ground structure includes a first section, a first circular section, a second section, a second circular section and a third section that are connected to each other in sequence in a second direction perpendicular to the first direction. The second section is covered by the primary microstrip line in a vertical direction perpendicular to the first and second faces. The primary microstrip line has a width equal to a minimum length of the second section. As such, the filtering effect can be improved.

Abstract: A step impedance resonator filter including a first resonator and a second resonator is disclosed. The first resonator includes a first coupled line and a first tapped line connected to the first coupled line. The second resonator includes a second coupled line and a second tapped line connected to the second coupled line. The second coupled line is coupled with the first coupled line. The first tapped line has a first central line which is spaced from an end face of the first coupled line at a first distance. The second tapped line has a second central line which is spaced from an end face of the second coupled line at a second distance. The first distance is larger than the second distance. As such, the performance of the step impedance resonator filter can be improved.

Abstract: A step impedance resonator filter including a first resonator and a second resonator is disclosed. The first resonator includes a first coupled line and a first tapped line connected to the first coupled line. The second resonator includes a second coupled line and a second tapped line connected to the second coupled line. The second coupled line is coupled with the first coupled line. The first tapped line has a first central line which is spaced from an end face of the first coupled line at a first distance. The second tapped line has a second central line which is spaced from an end face of the second coupled line at a second distance. The first distance is larger than the second distance. As such, the performance of the step impedance resonator filter can be improved.

Abstract: A filter configuration including a substrate, a primary microstrip line and a first defected ground structure is disclosed. The substrate has a first face and a second face. The second face is a ground face. The primary microstrip line is arranged on the first face and extends in a first direction. The first defected ground structure is arranged on the second face. The first defected ground structure includes a first section, a first circular section, a second section, a second circular section and a third section that are connected to each other in sequence in a second direction perpendicular to the first direction. The second section is covered by the primary microstrip line in a vertical direction perpendicular to the first and second faces. The primary microstrip line has a width equal to a minimum length of the second section. As such, the filtering effect can be improved.