Waffle-iron Waveguide Filter
Analysis of Spurious
To compute you need to
download
MathCAD spreadsheet
This spreadsheet is to evaluate spectrum of spurious resonances, which can possibly occur in waffle-iron harmonic filter and cause parasitic transmission in pass-band or roll-off
of the filter. (See notes on bottom)
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Enter dimensions and parameters of "waffle-iron" structure
(Enter 0 for mm and 1 for inches)
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Program Body (do not edit)
SCROLL DOWN TO SEE RESULTS
SCROLL DOWN TO SEE RESULTS
SCROLL DOWN TO SEE RESULTS
SCROLL DOWN TO SEE RESULTS
WAIT UNTIL EIGEN VALUES
ARE COMPUTED !!!
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Q- value of resonances (to be adjusted to see spectrum of resonances)
Frequency range in GHz (starting and ending points of sweep)
Important Design Rules
1. Design pass-band must be clean of spurious spectrum
2. Design stop-band must be clean of spurious spectrum
3. When designing waffle-iron filter always check frequency responses corresponding to modes of higher order (TE20, TE30, etc.)
Notes
This spreadsheet is to evaluate the spurious spectrum. It shows layout of potential spurious resonances on frequency axis, but it does not mean all those resonances will present in reality. Theoretically only resonances having particular symmetry order can occur. However, practically, any of those resonances might be excited because of asymmetry caused by production inaccuracy.
