Full-wave analysis of fundamental modes of a multicoupled strip line with ferroelectric film

The properties of a multicoupled microstrip line (MSL) with a thin control ferroelectric layer have been analyzed in terms of a full-wave model based on the method of moments in spectral domain. The Q values for all fundamental modes and their contributions to MSL losses are determined. It is established that various fundamental modes in multicoupled MSLs are characterized by significantly different Q values. The proposed method has been applied to the analysis of characteristics of an MSL-based ferroelectric microwave phase shifter. The figure of merit F of the phase shifter has been calculated for each fundamental mode. The results of analysis lead to a conclusion that, by exciting a fixed mode characterized by the maximum Q value, it is possible to obtain an MSL-based phase shifter possessing the optimum F at a minimum necessary level of the control voltage. (C) 2005 Pleiades Publishing, Inc.