ring resonator

hello
I simulate microstrip ring resonator with FDTD and matlab code, above resonator lossy material
( relative permibelity Er and conductivity segma), my problem resonant frequency (s21) don't change with change of Er and segma else in free space is change for example when 1-Er=1 and sgma=0 for free space first resonant (fr1)is 3 GHz
2-Er=3 segma=0.1 fr1=2.7GHz
3-Er=4 segma=0.1 fr1=2.7GH
and so one
please help me maybe error in step size final time step. and I want information about microstrip ring resonator
thanks

Hi there,

if i understood your message correctly, then the most probable source of error is your impedance calculation. Maybe you dont run the simulation long enough to get enough sampling points for your FFT. or maybe the gaussian pulse you use as a source is not wide-band enough to cover all the spectrum u need and hence the correct modes of the antenna cannot be excited.

Also, how do you plan to obtain the radiation pattern

thank you a lote Mr. settmar
for ur replay How can i determine time step about the radiation pattren i dont know but i really have interist to know how if u have idea:D

Hello,

there is a book called ''the finite difference time domain method for electromagnetics'' by Kunz and Luebbers, there is a chapter there that will be very helpful on how to set up properly your gaussian excitation pulses.
Also, another book called numerical recipes for fortran has a really good FFT algorithm. I suggest you try 8192 timesteps (2^13) or 16384 (2^14).
The timestep should obviously depend on the courant stability criterion and i suggest your cell sizes are a maximum of lamda/20, lamda being the wavelength of your resonant frequency.

And for the record I am a ''Miss'' and not ''Mr'' :D

hope this helps!

Hello
thanke you Miss settmar, really you help me. I'll try to find book
can I get ur Email
my email
am_200221821@yahoo.com

Hello...
Im graduated in collage in North Sumatera University (indonesia).

i'm want to ask to all of u about microstrip rectangular patch antena using FDTD method.

How to find resonance frequency & impedance using the FDTD method?

this is very urgent to finishing my studied...

thanks before...

Hello
i have a fiber ring resonator in my problem. i must solve it with FDTD method.How to find resonance frequency and BOUNDARY CONDITION?


thanks