Microwaves, in the central portion of the nonionizing spectral region of the electromagnetic spectrum, find use in chemical technology as a power source. Microwaves penetrate macroscopic objects further than any other type of nonionizing radiation. Most of the applications of microwave technology are based on the heating effects related to the dielectric properties of the various media. The major consumer product is the microwave oven. In the U. S., it is estimated that 90% of households own a microwave oven.
The frequency allocations for microwave technology and the basic principles for processing are described. Power sources, applicators, and instruments are discussed. Hazards of exposure to microwaves and interference with other electronic equipment are given consideration. A main use of microwave power is in food processing. Other uses are numerous and include medicine, biological, agriculture, and chemical applications. Details on the use of microwave technology in chemical synthesis applications is described in detail elsewhere in the Encyclopedia. Waste treatment, recycling of plastics, ceramics processing , and microwave plasmas are included in the use discussions.