An analysis of a door seal structure of a microwave oven with an inserted sheet‐type lossy material using FDTD method

By means of the three-dimensional FDTD, the shield effect is studied for a sheet-type lossy material inserted in the gap between a microwave oven body and its door as a way to suppress the microwave leakage in place of the generally used choke structure. Specifically, the shield effect versus the inserted length of the lossy material and the gap is studied by means of the TE40 mode, which has the closest shape to the leakage field among various higher-order modes. It is shown that a shield effect of more than 30 dB can be exhibited if a certain lossy material completely fills the gap and that the inserted length of more than 50 mm is needed to obtain a shield effect of more than 30 dB if there is gap of 1 mm. Hence, the shield effect in a practical situation is quantitatively confirmed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(9): 13–20, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1121