Abstract: A microwave heating device includes at least two radiating portions that are adapted to radiate microwaves to the heating chamber and can be operated according to a plurality of operational configurations that differ in frequency and/or in phase shift(s) between the radiated microwaves. Data of energy efficiency, as a function of operational configurations, can be obtained for a product in the heating chamber. For example, energy efficiency data are obtained through a learning procedure. The obtained data can be processed to select one or more operational configurations ranking high in energy efficiency and a heating procedure for the product inside the heating chamber can be executed by operating the at least two radiating portions according to the selected one or more operational configurations.

Abstract: A microwave heating device and a method for operating a microwave heating device to heat a product inside a heating chamber includes at least two radiating portions that are adapted to radiate microwaves to the heating chamber and can be operated according to a plurality of operational configurations that differ in frequency or phase shift(s) between the radiated microwaves. A learning procedure can be executed by sequentially operating the radiating portions in several operational configurations for which energy efficiency data are calculated. An operating frequency can be selected via an algorithm that optimizes a mathematical function based on energy efficiency data. An operational configuration with a maximum energy efficiency at the selected operating frequency may be taken as a reference.