Analysis of arbitrary gap coupling in a patch filter

Gap coupling has been used in different microwave circuits for coupling between circuit elements. For patch filters, to ensure that the loaded Q remains high, instead of direct connections, gap couplings can be used. Because of the high Q, high accuracies are required to model both the patch itself and the gap coupling without sacrificing the speed of computation. High accuracy in patches has in fact been obtained in our previous works, this paper therefore concentrates on the accuracy in the modeling of gap coupling. For fast computation of a narrow gap, a novel transmission line model is presented