High Band Rejection Improvement for Coupled Line Using Defected Ground Structure Technology

Abstract

In this article a high band rejection has been achieved by using Defected Ground Structure (DGS) technology depending on adding couple poles to improve the inverter and resonator, it will get a high rejection characteristic with good return loss by using this technology. The proposed coupling filter applied to a bandpass diplexer filter with two bands of 2.6 GHz and 6 GHz implemented on RO4350 substrate has a dielectric constant of 3.67 with 14×75 mm overall dimensions. The design technique for the suggested coupled - line filter is implemented based on the theory of coupled - line filters and the DGS equivalent circuit. The simulation results after using DGS show better agreements with theoretical results.