Calculating the Resonant Frequency
Eigenmodes are the resonances of the structure. The eigenmode solver finds the resonant frequencies of the structure and the fields at those resonant frequencies. For a Driven Solution, HFSS solves the following matrix equation (for a lossless case):
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(1) |
where
- S and T are matrices that depend on the geometry, the materials, and the mesh.
- x is the electric field solution.
- ko is the free-space wave number.
- b is the value of the source defined for the problem.
However, in order to find the resonances of the structure, the eigenmode solver sets b to zero, and solves the equation
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(2) |
for sets of (ko,x), one ko for every x. The variable x is still the electric field solution, and ko is the free space wave number corresponding to that mode. The resonant frequency of the eigenmode can be found using:
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(3) |
where
- c is the speed of light.