Microstrip stepped impedance filters with variable dielectric or variable width

A stepped impedance filter has been realised on a modified substrate. The change in impedance was achieved by varying the dielectric constant in the substrate while maintaining a constant width of the microstrip. In contrast to conventional stepped impedance filters the impedance is varied by the dielectric constant instead of the microstrip line width. The manufactured filter was measured and compared with an equivalent conventional stepped impedance filter. It is shown that the modified substrate technology could offer an alternative to the standard approach for the stepped impedance filter. In combination with new materials with a high permittivity the technology could also offer a denser package since the microstrip width could be controlled as desired.