Microwave transmission is the transmission of information by microwave radio waves. Convection microwaves are more expensive than conventional microwave ovens. A convection microwave oven is a combination of a standard microwave and a convection oven. Lutefisk may also be cooked in a microwave oven. This is the case inside a microwave oven. Food and cookware taken out of a microwave oven are rarely much hotter than . Amana produced the first practical commercial microwave oven in 1967. The radiation produced by a microwave oven is non-ionizing. Individual portions heatable in a microwave oven are also sold. Wireless networks are susceptible to interference from devices such as microwave ovens. Metallised films are used as a susceptor for cooking in microwave ovens. He also mentioned how he had a claim for inventing the microwave oven. The magnetron is the type of tube used in all microwave ovens. Both of these resonances are at higher frequencies than the operating frequency of microwave ovens. This happens for infrared, microwave and radio wave radiation.