Measuring Electric Field Distribution in a Microwave Oven.

摘要

The microwave oven heats by radiation. The radiation consists of electromagnetic energy in the radio-frequency spectrum. In a microwave oven the electromagnetic waves are produced by a magnetron. The waves are coupled by a wave guide to the oven cavity in which the food is exposed to the electromagnetic waves. As microwave energy enters the oven cavity, distribution of the incident waves is accomplished by a wave stirrer. Reflected waves from the inner metal surface of the oven cavity also contributes to the distribution pattern of microwave energy. Because microwave energy travels in a straight line, reflected and incident waves contribute to a specific distribution. The specific distribution is referred to as the standing wave pattern. In the zone where the energy is reflected from the walls and floor of the oven cavity, the metal has a reducing effect close to its surface. This zone is about 1-2 cm. Therefore, areas of high and areas of low electric fields are produced. The effect of uneven heat distribution on the quality of portioned food is one of the major problems of microwave heating.