Microwave heating apparatus and method of operating such a microwave heating apparatus

1. A method of operating a microwave heating apparatus comprising a cavity and at least one microwave source for feeding microwaves to the cavity via a plurality of feeding ports, said method comprising the steps of:

measuring, for at least one frequency or within a frequency range, a power of the microwaves reflected back to the microwave source for each one of at least part of the plurality of feeding ports; and

selecting, using a control unit, at least one of the plurality of feeding ports based on the measured power in order to feed microwaves to the cavity via the at least one selected feeding port during operation of the microwave heating apparatus at said at least one frequency or within said frequency range.

2. The method of operating a microwave heating apparatus of claim 1 further comprising the step of:

providing a computer program, loadable into the microwave heating apparatus, the computer program comprising software code portions for the microwave heating apparatus to perform the steps of measuring the power of the microwaves and selecting the at least one of the feeding ports.

3. The method of claim 1 , wherein selecting at least one of the plurality of feeding ports based on the measured power includes feeding microwaves to the cavity only via the at least one selected feeding port during operation of the microwave heating apparatus at said at least one frequency or within said frequency range.

4. A method of operating a microwave heating apparatus including a cavity adapted to receive a load to be heated, at least one microwave source and a plurality of feeding ports connected to the microwave source and the cavity for feeding microwaves to the cavity, said method comprising:

measuring, for at least one frequency or within a frequency range, a power of microwaves reflected back to the at least one microwave source for at least one of the plurality of feeding ports;

selecting, based on the power of the microwaves reflected back to the at least one microwave source, at least one of the plurality of feeding ports using a control unit; and

feeding microwaves to the cavity via the at least one of the plurality of feeding ports during operation of the microwave heating apparatus at the at least one frequency or within the frequency range.

5. The method of claim 4 , wherein the selecting of the at least one of the plurality of feeding ports is performed such that a ratio between power emitted from the at least one microwave source and the power of the microwaves reflected back to the at least one microwave source is above a threshold for the at least one frequency or at a frequency within the frequency range.

6. The method of claim 4 , wherein the plurality of feeding ports feed the microwaves into the cavity at different locations.

7. The method of claim 4 , further comprising: determining at least one specific frequency or a specific frequency range for performing power measurements in accordance with input data relating to at least one of the load to be heated and a preselected cooking program.

8. The method of claim 4 , further comprising: selecting a group of the plurality of feeding ports for which respective measured powers of microwaves reflected back to the at least one microwave source are below a threshold in a common frequency sub-range of said frequency range.

9. The method of claim 4 , wherein feeding microwaves to the cavity includes feeding microwaves from a plurality of microwave sources, with each of the plurality of microwave sources being connected to the at least one feeding port.

10. The method of claim 9 , wherein the at least one feeding port includes a set of feeding ports and said method further comprises feeding microwaves to a specific region of the cavity via the set of feeding ports.

11. The method of claim 4 , further comprising: operating the microwave heating apparatus such that a ratio between power emitted from the at least one microwave source and the power of microwaves reflected back to the microwave source is maintained as high as possible.

12. The method of claim 4 , wherein the step of selecting at least one of the plurality of feeding ports includes selecting at least two of the plurality of feeding ports, or at least two sets of the plurality of feeding ports, for which the power of the microwaves reflected back to the at least one microwave source are measured to be below a threshold in two different sub-ranges, respectively, of the frequency range.

13. The method of claim 12 , further comprising: operating the microwave heating apparatus by switching between the at least two of the plurality of feeding ports or the at least two sets of the plurality of feeding ports.

14. The method of claim 4 , wherein the at least one of the plurality of feeding ports is selected based upon input data relating to at least one of the load or a preselected cooking program.

15. The method of claim 4 , further comprising: determining, based on input data relating to at least one of the load or a preselected cooking program, a location for measuring the power of the microwaves reflected back to the at least one microwave source.

16. The method of claim 4 , further comprising: employing a frequency controllable microwave generator or a solid-state based microwave generator as the at least one microwave source.

17. The method of claim 4 , wherein feeding microwaves to the cavity includes feeding microwaves to the cavity only via the at least one selected feed port during operation of the microwave heating apparatus at the at least one frequency or within the frequency range.