Microwave manufacturers typically use mechanical components including custom oscillators, voltage regulators and microcontrollers. These materials cohesively function to generate radar waves that raise internal temperatures of foods within microwave ovens.
While the wavelengths are emitted as electromagnetic energy, they do not cause food to become radioactive due to their position on the energy spectrum's non-ionizing range from radio waves to physical light. They react to metals without detaching charged particles, producing atoms containing unbalanced plus or minus charges as elements of high frequency radio waves.
Countertop microwave ovens developed throughout radar research projects using magnetron vacuum tubes. Designed by Percy Spencer in 1946, the original microwave oven featured a box constructed of metal in which microwave energy flowed through a small opening. The resulting electromagnetic field became contained within the box, heating objects placed inside with dense internal pressure. Early designs were then tested in experiments to expedite food preparation methods. Thirty years later, microwaves were in worldwide demand and manufactured on a global scale.
As contemporary kitchen appliances, microwaves may be designed for both commercial and domestic use. Household models perform basic cooking functions like heating and defrosting, while commercial designs are built to prepare food quickly in large quantities. Microwave properties may additionally be incorporated with conventional ovens to heat food through electric convection technology.