Patent ID: 8242862

Claim:
A tunable bandpass filter comprising: a dielectric substrate having a first surface opposite to a second surface; a conductive ground plane disposed on the first surface; a conductive trace pattern disposed on the second surface, the trace pattern defining a phase velocity compensation transmission line section comprising a series of spaced T-shaped conductor portions alternating with at least one TL-shaped conductor portion; at least one varactor diode coupled to a first T-shaped conductor portion of the series of T-shaped conductor portions and to the conductive ground plane; and bias control circuitry coupled to the first T-shaped conductor portion, wherein the bias control circuitry is configured to control the at least one varactor diode, wherein the at least one TL-shaped conductor portion comprises a parallel leg, a secondary parallel leg, and a transverse stub positioned between the parallel leg and the secondary parallel leg, wherein the parallel leg and the secondary parallel leg are each oriented parallel to a filter axis, and wherein the secondary parallel leg consists of a rectangular shaped leg.