Size reduction and harmonic supression in coplanar rat-race coupler using defected ground structures

In this paper, we have proposed, verified and studied defected ground structures (DGS) in coplanar rat-race coupler to reduce its size and harmonic suppression in transmission characteristics. The dumbbell geometry has been chosen as a DGS unit-cell in a systematic manner in the proposed structure. The EM simulation results from IE3D tool presented with experimental validation to study the transmission behavior of proposed structures. The operation frequency has been reduced from 5.4 GHz down to 4.4 GHz after introduction of defected ground structures along the suppression of higher order harmonics.