Wide Stopband Microstrip Bandpass Filter Based on a Compact Slotted Ground Structure

A new concept for implementing a bandpass filter by employing a discontinuity in the feed microstrip line in the upper layer and modified dumbbell-shaped slots etched in the ground plane is proposed. The effect of the slot area on the bandpass filter performance is examined. The proposed bandpass filter showed wide stopband and low insertion loss. To further verify the new concept, the structure is implemented and the measurement results are found to be in good agreement with the simulation ones. The proposed structure can be used in various microwave circuits.