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Re: The different between transient/frequency solver in CST
Time Domain Solver - good for big structures (less memory hungry), arbitrary excitation signals (like square waves or pulses), broadband problems
frequency Domain Solver - good for small problems (like RF-CMOS structures), use of Floquet Modes applied to non-normal incidence (on Frequency Selective Surfaces), low frequency applications (like RFID for the kHz-range) and very high Q-filters (if simulated in time domain require a huge time to get it done).
Both solvers are original from the FIT - Finite Integration Technique - which works on the Integral Formulation of the Maxwell Equations.
I have a question regarding the frequency solver.
Usually I use the transient solver to simulate the antennas and the result is sufficient for me.
However, now I have a microstrip patch antenna, which is highly resonant structure. The transient sovlver gave me some ambiguous results. For example, when I simulate from 1 to 3 GHz, the S11 at 1.57GHz is -20dB. But when I solve from 1 to 20 Ghz, the S11 at 1.575Ghz becomes -7dB. Someone suggests that I should use the frequncy domain solver.
However, I encounter this problem everytime and the solver automatically stopped.
"The port number 1 is located inside the computation domain, but not backed with a solid block of PEC material".
Anyonw knows what this means????? I don't understand at all.