Abstract: A conveyorized microwave oven having two leakage suppression tunnels in series wherein the first tunnel includes a microwave choke and a second tunnel has a ferromagnetic layer covered with a smooth microwave transparent sheet. The choke tunnel presents a high impedance to microwave energy at the operating or fundamental frequency and the second tunnel attenuates spurious out-of-band radiation which propagates through the first tunnel and is typically concentrated at the harmonics. The ferromagnetic layer absorbs the broad-banded microwave energy and the smooth microwave transparent layer such as Lexan provides a surface that is easily cleanable and acceptable for use in cooking food. The sides of the second tunnel can be pivoted to an opened position by hinges to provide easy access to the inside for cleaning.