A New Type of Low Pass Filter With Defected Ground Structure

A new design method of low pass filters (LPF) using defected ground structure (DGS) on planar transmission lines such as microstrip and coplanar waveguide (CPW) is presented. LPF is designed easily by extracting the equivalent circuit elements of unit DGS and compensating the line width of capacitive transmission line. The proposed LPF does not have any open stub, discontinuity elements such as Tee-or Cross-junction, and the repeated low-high impedance elements, which have been essential for design of conventional LPF. Only two DGS patterns and one transmission line with broadened width are used for design of the proposed LPF. Simple structure, small size (49% of a conventional LPF), less discontinuities, non-existing of the high impedance lines, no need for wire bonding required in CPW discontinuities, and high power handling capability are obtained through the proposed LPF.