Edwin Jan Klein - Universiteit Twente

4.4 DropZone
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Simulation and analysis
The brute force fitting process used by the RFit program can have some problems
with very noisy measurements. While it is possible to filter some of this noise out of
the measurement, for instance using a Fast Fourier-Inverse Fast Fourier transform
(FFT-IFFT) based low-pass filter, this might also remove some important information
from the measurement. The program is therefore best used interactively by combining
computerized fitting with user experience to find the best possible fit.
For an experienced user, however, it is often relatively easy to estimate the depth of
both the trough and drop responses, even if these signals are subject to a lot of noise.
This is of importance since, for symmetric devices, the field coupling coefficients and
resonator losses can be found analytically using only these depths as the input,
thereby providing a very fast alternative fitting method. It is this method that was
implemented in the DropZone tool. The user interface of this tool, shown in Figure
4.4 allows a user to determine the field coupling coefficients and waveguide losses
from the through and drop responses or, if the drop response is not available, to at
least estimate the waveguide losses.
Figure 4.5. Dropzone user interface.