Design of compact extended-stopband microstrip low-pass filters by employing new mutual- coupling technique for defected ground structures (DGSs)

A new technique for reducing the size, and improving the rejection in the stopband of a low-pass filters using modified DGSs is proposed . An equivalent circuit model is used to investigate the DGS characteristics. It will be demonstrated that the filter can provide a sharp transition and a wide rejection in the stop-band. To further verify the new technique, a filter using the deformed DGSs has been fabricated and measured. The agreement between the simulated and measured results confirms the effectiveness of the proposed concepts.