Microwave impedance matching film for microwave cooking

A package for storing and microwave heating food comprising:

• (a) a package body substantially transparent to microwave energy forming a food receiving cavity including a bottom panel and a top panel with side panels joining said bottom panel with said top panel;
• and
• (b) impedance matching means provided on an extended surface of at least one of said panels for impedance matching microwave energy entering the package, wherein said impedance matching means is convex such that the center thereof has a thickness greater than the thickness at the periphery thereof to focus impedance matched microwave energy toward the food to elevate the temperature of the food by increasing the amount of microwave energy directed to the food in an area corresponding to the size of the impedance matching means and spacing of said impedance matching means from the food without interacting with the microwave energy to produce heat wherein said impedance matching means comprises a continuous film of generally planar flakes embedded in a dielectric binder.

A composite material for impedance matching microwave energy without interacting with the microwave energy to produce heat comprising:

• (a) a substrate substantially transparent to microwave energy;
• and
• (b) impedance matching means provided on at least a portion of the substrate for impedance matching microwave energy, said impedance matching means comprising a contiguous film of generally planar flakes embedded in a dielectric binder wherein said flakes comprise aluminum having a longest average dimension within the range of about 8-75 micrometers and a thickness within the range of about 100-500 .ANG..

A composite material for shielding a food item from microwave energy positioned proximate thereto comprising:

• (a) a substrate substantially transparent to microwave energy;
• and
• (b) a shielding means provided on at least a portion of the substrate for reducing the amount of microwave energy reaching a food item positioned proximate thereto, said shielding means comprising a contiguous film of generally planar flakes embedded in a dielectric binder in an amount sufficient to reduce microwave energy reaching the food item when said composite material is positioned proximate thereto wherein said flakes comprise aluminum having a longest average dimension within the range of about 8-75 micrometers and a thickness within the range of about 100-500 .ANG..

A package for storing and microwave heating food comprising:

• (a) a package body substantially transparent to microwave energy forming a food receiving cavity including a bottom panel and a top panel with side panels joining said bottom panel with said top panel;
• and
• (b) impedance matching means provided on a surface of at least one of said bottom panel, top panel and side panels for impedance matching microwave energy entering the package, said impedance matching means comprising a contiguous film of flakes embedded in a dielectric binder wherein said impedance matching means is sized and spaced with respect to the food to cause impedance matching to elevate the temperature of the food by increasing the amount of microwave energy directed to the food in at least a predetermined area thereof dependent upon the size and spacing of said film, wherein said flakes are generally planar having a longest average dimension within the range of about 8-75 micrometers and a thickness within the range of about 100-500 .ANG..