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A microwave oven uses dielectric heating to cook food.. Dielectric heating, also known as electronic heating, radio frequency heating, and high-frequency heating, is the process in which a radio frequency (RF) alternating electric field, or radio wave or microwave electromagnetic radiation heats a dielectric material.
A microwave oven does not pose this problem. Food and cookware taken out of a microwave oven are rarely much hotter than 100 °C (212 °F). Cookware used in a microwave oven is often much cooler than the food because the cookware is transparent to microwaves; the microwaves heat the food directly and the cookware is indirectly heated by the food.
Inside a microwave oven, there really do exist EM free-space microwaves, since the wavelength is far shorter than the gap between the metal walls. However, inside the metal plates of a dielectric heater, that isn't true, so the entire effect is near-field, without production or absorption of any genuine radio waves-- even if the frequences are ...
A microwave oven passes microwave radiation at a frequency near 2.45 GHz (12 cm) through food, causing dielectric heating primarily by absorption of the energy in water. Microwave ovens became common kitchen appliances in Western countries in the late 1970s, following the development of less expensive cavity magnetrons. Water in the liquid ...
The most common problem exhibited by dielectric resonator circuits is their sensitivity to temperature variation and mechanical vibrations. [8] Even though recent improvements in materials science and manufacturing mitigated some of these issues, compensating techniques still may be required to stabilize the circuit performance over temperature ...
A liquid dielectric is a dielectric material in liquid state. Its main purpose is to prevent or rapidly quench electric discharges . Dielectric liquids are used as electrical insulators in high voltage applications, e.g. transformers , capacitors , high voltage cables , and switchgear (namely high voltage switchgear ).
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So these antennas can have lower losses and be more efficient than metal antennas at high microwave and millimeter wave frequencies. [1] Dielectric waveguide antennas are used in some compact portable wireless devices, and military millimeter-wave radar equipment. The antenna was first proposed by Robert Richtmyer in 1939. [2]