# S-Parameter Coupling in a Stepped Waveguide Section

Calculate the transmission and reflection for a stepped waveguide transition from the Ku- to X-band. Use two solver methods, the method of moments (utilising waveguide ports) and the finite element method (utilising FEM modal ports).

The waveguide consists of a Ku-band section and an X-band section. Only the
H_{10} mode with cutoff frequency,
${f}_{c}=\frac{{c}_{0}}{2a}=9.4871$
GHz is considered.

- a = 15.8 mm
- b = 7.9 mm

- a = 22.9 mm
- b = 10.2 mm

Calculate S-parameters from the cutoff frequency to 15 GHz.