A microstrip filter with adjustable rejection band

This paper presents a novel microstrip filter design for tunable rejection band. The proposed was mainly with a defected ground structure. A ladder-shaped slot, which was located below the 50-Omega microstrip line, was embedded in the ground plane. For a fixed dimension, about 100% adjustment in rejection band was obtained by simply modifying the geometry parameters of the embedded slot. Experimental results indicate that the band control and design simplicity of the microstrip bandstop filter can be achieved simultaneously. In this article, the author discusses the design and experimental results for the adjustable bandstop filter