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A microwave heating device is comprised of a microwave reflective member having positioned adjacent thereto magnetic microwave absorbing material. The absorbing material, by being magnetic, will heat by coupling of the magnetic component of microwave radiation. The thickness of the absorbing materia

A microwave heating device is comprised of a microwave reflective member having positioned adjacent thereto magnetic microwave absorbing material. The absorbing material, by being magnetic, will heat by coupling of the magnetic component of microwave radiation. The thickness of the absorbing material is such that at the Curie temperature the material will reflect at least about 65% of the incident microwave radiation. The absorbing material has a volume resistivity value R, at room temperature, in ohm cm of greater than about the value where Log R=(Tc/100)+2 where Tc is the Curie temperature (°C.) of the material. By the proper combination of thickness, high resistivity and Curie temperature, the device is temperature self-limiting in a microwave field and can be used to heat objects in contact with the device to predetermined temperatures in spite of wide fluctuations in microwave power or power uniformity.

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A device for use in a microwave radiation environment which device will absorb microwave radiation to produce heat and elevate the temperature of the device, said device including: a microwave reflective member; and a lossy magnetic ferrite containing material of a type having a Curie temperature, s

A device for use in a microwave radiation environment which device will absorb microwave radiation to produce heat and elevate the temperature of the device, said device including: a microwave reflective member; and a lossy magnetic ferrite containing material of a type having a Curie temperature, said ferrite being in heat transfer relationship with a surface of said member with said ferrite containing material having thickness (d) in a direction generally normal to said surface such that at the Curie temperature the ferrite containing material will reflect at least about 65% of the impinging microwave radiation in the frequency range of about 300 MHZ to about 105 MHZ, said ferrite containing material having a volume resistivity (R) in ohm cm of greater than about a value where Log R=(Tc/100)+2 (where Tc=the Curie temperature in °C. of the ferrite material) at room temperature.