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 × 100 mm. Limits of the approach may come from the requirements of small length of the filter (<1 m) and large height of waveguide.