The hybrid finite-element/finite-difference time-domain (FETD/FDTD) method
recently proposed to handle arbitrarily shaped dielectric objects is employ
ed to investigate electromagnetic problems of high Q systems for which the
transient response over a very long duration is necessary. To begin with, t
he paper demonstrates that this hybrid method mag suffer from late-time ins
tability and spurious de modes. Then an approach which combines the tempora
l filtering and frequency shifting techniques is presented to overcome sequ
entially and, respectively, the two drawbacks. Its accuracy is validated by
the favorable comparison with several different methods for the analysis o
f resonant frequencies and Q factors of the various modes in an isolated di
electric resonator. Finally, the present method is applied to calculate the
scattering parameters on the microstrip line due to the presence of the cy
lindrical dielectric resonator.