Raute Oyj

Pete Ristola

Jaakko Vilo

Jerzy Piotrowski

In a microwave heating apparatus, the fundamental TEmode of the standard waveguide () having a standard rectangular cross-section is fed into an elongated heating cavity () having an enlarged rectangular cross-section in which the shorter side of the standard waveguide is enlarged to a length which can accommodate the desired width of a board () to be heated. A pair of lateral slots () is provided parallel in the opposite enlarged walls () of the heating cavity () to form a track for the board () to travel across the cavity. As the initially longer sidewall () of the standard waveguide is unchanged, the fundamental mode is not affected but the electric field is uniformly distributed along the width of the board () traversing the electric field and the cavity. As a result, wider products can be heated and a more uniform heating pattern can be achieved.

Apparatus for microwave heating of planar products

The invention relates to a microwave waveguide element for matching a standard waveguide input port to an enlarged waveguide output port. In the waveguide element, a plurality of intermediate waveguide segments is cascaded in the propagation direction of the microwave energy to first split the waveguide element into two symmetrical waveguide branches and then combine the branches at the output port. Thus, the width of the waveguide element is gradually enlarged and the input port is matched to the output port. The intermediate waveguide segments are preferably dimensioned such that respective characteristic impedances are approximately matched with each other for the fundamental mode.

Apparatus for microwave heating of a planar product including a multi-segment waveguide element

An apparatus for heating a board product containing glued wood is disclosed. The apparatus includes a heating chamber through which the board product passes. The board product passes through a heating field in the heating chamber provided by means of microwave energy applied perpendicular to the board plane. The clearances between respective side edges of the board and side walls of the heating apparatus are filled by slide pieces made of a material that has a small loss tangent and a low dielectric factor. The slide pieces correct the form of the heating field affecting the board plane.

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Lammi, Finland

Pete Ristola