ELECTROMAGNETIC HEATING
An electromagnetic heater for heating an irregularly shaped object, including: a cavity within which an object is to be placed; at least one feed which feeds UHF or microwave energy into the cavity; and a controller that controls one or more characteristics of the cavity or energy to assure that the UHF or microwave energy is deposited uniformly in the object within ±30% over at least 80% of the volume of the object.
1 . A method of electromagnetic heating, comprising:
subjecting an object, that is to be heated, to UHF or microwave energy in an amount capable of heating the object;
determining an absorbed amount of energy that is absorbed by the object; and
adjusting the heating when a desired amount of energy is absorbed.
2 . The method of claim 1 , further comprising placing said object in a cavity; wherein said subjecting comprises feeding said UHF or said microwave energy into the cavity via a plurality of feeds.
3 . The method of claim 1 , wherein said subjecting comprises providing an energy concentrating element on, in or near the object; placing said object and the energy concentrating element in a resonant cavity; and irradiating the object and the element to cause a concentration of energy at selected places in the object.
4 . The method of claim 2 , wherein the frequencies of said energy fed to two of the feeds differs by at least 8 MHz.
5 . The method of claim 1 wherein said subjecting the object to said energy includes transmitting a plurality of frequencies covering a band of at least 2%.
6 . A method according to claim 5 , wherein said band is at least 20 MHz wide.
7 . A method according to claim 6 , wherein said band is at least 20 MHz wide.
8 . The method of claim 1 , wherein said adjusting comprises subjecting said object during a heating thereof, to a static or low frequency electric or magnetic field effective to increase the uniformity or efficiency of said heating.
9 . The method of claim 2 , wherein said adjusting comprising adjusting the humidity of or cooling the air in said cavity.
10 . Apparatus for electromagnetic heating comprising:
a cavity for supporting an object to be heated;
at least one RF source for feeding at least one feed so as to subject said object to UHF or microwave energy in an amount capable of heating the object;
a sensor for determining an absorbed amount of said energy that is absorbed by the object; and
wherein said at least one RF source is configured for adjusting said heating when a desired amount of energy is absorbed.
11 . The apparatus of claim 10 , wherein said at least one RF source comprising a source of static or low frequency electric or magnetic field arranged to subject said object to an electric or magnetic field, effective to affect the heating of an object in the cavity.
12 . The Apparatus of claim 10 , wherein said at least one feed comprises a plurality of feeds and wherein the radiating elements of at least two feeds is different.
13 . The Apparatus of claim 10 , wherein said at least one feed comprises a plurality of feeds and wherein the device is capable of transmitting frequencies of said energy fed into said feeds that differ by at least 8 MHz.
14 . The Apparatus of claim 10 , wherein the frequency difference is at least 20 MHz.
15 . The Apparatus of claim 10 , wherein said at least one RF source having a power output of at least 50 watts and being sweepable over a frequency range of greater than 0.5% with an efficiency of greater than 40%.
16 . The Apparatus of claim 15 , wherein said at least one RF source comprises a signal generator that produces selective frequencies within a band and an RF amplifier.
17 . The Apparatus of claim 15 , wherein said at least one RF source is sweepable over a frequency range greater than 2%.
18 . The Apparatus of claim 10 , wherein said at least one RF source having at least one RF source having a power output of at least 50 watts and being sweepable over a frequency range of greater than 200 MHz with an efficiency of greater than 40%.
19 . The apparatus according to claim 10 , wherein the cavity comprises at least one adjustable field adjusting element within the cavity; and wherein adjusting the cavity comprises adjusting the at least one field adjusting element.
20 . The apparatus according to claim 10 , comprising a signal generator that produces selective frequencies within a band and an RF amplifier.