GB1277427A - Microwave heating apparatus - Google Patents

Abstract

1277427 Microwave drying R J MEREDITH 23 Feb 1970 [22 Nov 1968] 55408/68 Heading F4G [Also in Division H5] Microwave heating or drying apparatus comprises a series of separate waveguide sections 1 arranged side-by-side and formed with slots defining a channel 3, Figs. 3, 6, (not shown), for the passage therethrough of webs of material or a conveyor belt carrying material, to be heated, and magnetic and/or electrical coupling means between each adjacent pair of sections arranged alternately at the ends of the sections and comprising coupling loops or coupling probes. Each coupling probe, Fig. 1, comprises an outer conductor 4 and inner conductor 5 the conductor 4 being supported by a block 6 of dilute material. The ends of the inner conductor may be supported by dielectric or metal rods 7, 35.4. Each probe may be tapered or have adjustable projecting elements such as conducting or insulating discs for impedance watching. Each coupling loop, Fig. 7, or Figs. 5, 6, 8, 9, (not shown), comprises an outer conductor 9 extending between the two adjacent sections and a longer inner conductor 10 the end portions of which form loops secured to the upper part 2a of the waveguide section supports 2 or to the waveguide sections themselves. The lower part 1b, 2b, of the waveguide sections 1 and supports 2 are fixed and the upper parts 1a, 2a, are pivotally mounting thereto by hinges (not shown) to give access to the interior of the apparatus, e.g. for cleaning. The coupling loops or probes are connected together by coaxial transmission lines or slab lines bridging the intermediate section or sections where the apparatus has more than one series of interconnected waveguide sections with the sections arranged alternatively. Applications of the apparatus are to the drying of paper webs, the cooling of objects such as biscuits on a conveyor belt, the drying of powder or granular materials on a conveyor belt, and the curing of materials. One of the end sections of the waveguide section 1 is connected to a magnetron (not shown) and the appropriate end of the other end section has connected to it a terminating rod or a short circuit termination.