FDTD analysis of microstrip configurations incorporating gain blocks

The FDTD method is a full wave numerical method which has been extended to analyse hybrid systems incorporating lumped elements and semiconductor devices (using equivalent circuits). A simple implementation of a matched gain block in the extended FDTD algorithm is proposed. The behaviour of the gain block is examined through a simple circuit to validate its characteristics. As a test structure of considerable complexity, a novel microstrip active circulator is analysed. Results compared with those obtained using the HP-MDS circuit simulator show good agreement