Numerical Study of Eigenmodes Propagation Through Rectangular Waveguide with Quarter-Wave Chokes on the Walls

The problem of improvement of input/output ports construction of
conveyor belt microwave heating system is considered. The desirable construction
of the ports should not allow electromagnetic energy to escape from
the microwave processing chamber, i.e. must operate as stop band filter for a
number of eigenmodes. This paper contains numerical results illustrating performance
of the quarter-wave chokes as a band-stop filter for large cross-section
waveguide. The results were obtained by direct FDTD modeling of the system.
Presented results show possibility of effective eigenmode filtering for waveguides
with cross-section 780 x 100 mm. Limits of the approach may come
from the requirements of small length of the filter (<1 m) and large height of
waveguide.