coupling control in coupled microstrip lines using defected microstrip structure

this paper propose a simple approach for achieving the desirable coupling in coupled microstrip lines using defected microstrip structure (dms) with a constant space between two lines. dms creates a reject band, so firstly the s-parameters of the transmission line are obtained using a full wave electromagnetic simulator in order to determine stopband location and proper frequency region for control coupling. then by the suitable assuming according to specified criteria and analytical formulations, dimensions of proper dms are calculated. results have been verified by simulations and fabrication.