A Compact E-Shaped Patterned Ground Structure and Its Applications to Tunable Bandstop Resonator

In this paper, an E-shaped patterned ground microstrip bandstop resonant cell is proposed. In comparison to other bandstop resonators, it provides the advantages of a high-$Q$ factor, and a sharp transition knee within a small circuit area. This resonant cell is applied to the design of a tunable bandstop resonator. Due to the unique E-shaped pattern etched in the ground plane, the proposed resonant cell is able to provide tuning function within a small circuit area.