A trapezoidal microstrip bandstop filter with efficient suppression of undesired stopbands

Abstract

A new bandstop filter implemented as a cascade of trapezoidally shaped cells is presented. The proposed bandstop filter suppresses many undesired stopbands at higher frequencies. The cell design is specified by two variables and the initial filter is refined by optimizing the cell variables. The proposed design yields a robust structure suitable for fabrication. The proposed filter is fabricated and measured in a wide frequency range showing more efficient suppression than is reported in literature.