Bandstop Filter Using Slow-wave CPW Resonator with Defected Ground Structure

A novel slow-wave CPW resonator with defected ground structures (DGSs) in rectangular spacing-like shapes is investigated. This structure has an extremely compact size. Simulations and experimental results have verified that the structure provides a size reduction of about 33% against a conventional CPW resonator. Two bandstop filter examples are demonstrated. The bandstop filter realized with a fractional 20-dB bandwidth of 25% at 1.575 GHz includes a slow-wave CPW with DGS loaded periodically by four spiral-shaped resonators