Abstract:The co-simulation of the electromagnetic-field-and-circuits hybrid system was studied by employing the extended finite-difference time-domain (FDTD) algorithm. The extended FDTD’s principle and its iterative formula reflecting the embedment of lumped devices in the FDTD cells were introduced. As a sample

a microstrip double dipole antenna loaded with a lumped matching circuit at its input port

which was an antenna-and-circuit hybrid system

was simulated by the extended FDTD. In the simulation

S11 of this antenna was obtained by using a technique

which directly inserted the microstrip feeding line into a complex frequency shifted perfectly matched layer(CFS-PML) and executed the FDTD program twice.The loaded antenna was fabricated and measured.Results showed that the measurement agrees well with the simulation

and for the antenna

the lumped matching circuit slightly affects its gain and radiation patterns

but varies its resonant frequency and significantly changed its S11 curve.