Abstract: A microwave applicator for heating materials with microwaves. A coaxial transmission line is inserted in the material and coupled at one end to a source of microwaves. A shorting plate covers the other end of the cable and a plurality of radiating apertures are provided along the outer conductor. The use of a coaxial line avoids the minimum size requirements present with hollow waveguides. The coaxial line may be directly coupled to the output probe of a microwave generator by means of spring-finger contacts on the inner conductor of the coaxial line.

Abstract: The single-sided microwave applicator has a section of a microwave waveguide with an open end for receiving microwave energy and an end which is electrically shorted. A slot is located in one of the wide sides of the waveguide extending along the center line from the shorted end. A conductive ridge is mounted within the waveguide extending upward from the other side through the slot. One end of the ridge is connected to the shorted end of the waveguide, while the other end of the ridge is tapered from a point within the slot. The slot is generally in the order of 3/4 to 1 inch and at least 21/2 inches long, when the operating frequency is 2450 MHz. Since one end of the waveguide is shorted, standing waves are produced resulting in a non-uniform field having at least one maximum along the length of the slot. The electric field produced is non-radiating and its strength diminishes exponentially above the slot.

Abstract: A microwave leakage indicator for ovens in the form of a strip of encapsulated liquid crystal film backed by a layer of microwave absorbing material mounted around the edge of the door and overlapping the slot between door and oven where leakage might occur. The characteristics of the liquid crystal material are chosen such that if leakage above a preset level does occur at any location around the edge of the door, the absorbing material generates heat resulting in a quickly noticeable colour change in the liquid crystal film.

Abstract: The control system monitors the input power to and the output from the dryer applicator, and varies the input power to the applicator as a function of change in applicator efficiency and input power. The control system may consist of a first and a second circuit. The first circuit receives a signal P.sub.in.sbsb.1 from a first monitor and a signal P.sub.out.sbsb.1 from a second monitor. These signals are combined into an efficiency signal .eta..sub.1 to which a reference efficiency signal -.eta..sub.o is added. An amplifier having a predetermined gain K amplifies the resulting signal to produce -K(.eta..sub.1 -.eta..sub.o). The second circuit adds the signals P.sub.in.sbsb.1 from the first monitor, -K(.eta..sub.1 -.eta..sub.o) from the first circuit and P.sub.in.sbsb.o, a signal representative of input power for a reference condition, to produce an output signal I.sub.in.sbsb.1 - [P.sub.in.sbsb.o + K(.eta..sub.1 -.eta..sub.