• Percy Spencer invented the first microwave oven after
World War II from radar technology developed during the
war. Named the "Radarange", it was first sold in 1947.
Raytheon later licensed its patents for a home-use
microwave oven that was first introduced by Tappan in
1955, but these units were still too large and expensive for
general home use. The countertop microwave oven was
first introduced in 1967 by the Amana Corporation, which
was acquired in 1965 by Raytheon
• In 1947, Raytheon built the "Radarange", the first
commercially available microwave oven.It was almost 1.8
metres (5 ft 11 in) tall, weighed 340 kilograms (750 lb) and
cost about US$5,000 ($52,273 in today's dollars) each.
• A microwave oven, often colloquially shortened to
microwave, is a kitchen appliance that heats food
by bombarding it with electromagnetic radiation in
the microwave spectrum causing polarized
molecules in the food to rotate and build up
thermal energy in a process known as dielectric
• Microwave ovens heat foods quickly and
efficiently because excitation is fairly uniform in
the outer 25–38 mm of a dense (high water
content) food item.
• A microwave oven heats food by passing
microwave radiation through it. Microwaves
are a form of non-ionizing electromagnetic
radiation with a frequency higher than
ordinary radio waves but lower than infrared
• It was with the invention of the cavity magnetron
that the waves of a small enough wavelength
(microwaves) became possible. The magnetron was
originally a crucial component in the development
of short wavelength radar during WWII production
of electromagnetic .
• It is high-powered microwave generator that
worked at shorter wavelengths.
• The nucleus of the high-voltage system is the
magnetron tube . The magnetron is a diode-
type electron tube which is used to produce
the required 2450 MHz of microwave energy.
• It is classed as a diode
• A magnetic field imposed on the space
between the anode (plate) and the cathode
serves as the grid
•Microwave ovens are
popular for reheating
previously cooked foods
and cooking vegetables.
•They are also useful for
rapid heating of otherwise
slowly prepared cooking
items, such as hot
butter, fats, and chocolate.
the oven is used to heat
frying-oil and other very
oily items (such as
bacon), which attain far
higher temperatures than
that of boiling water.