Method of diagnosing an electromagnetic cooking device

1. A method for diagnosing an electromagnetic cooking device, the electromagnetic cooking device comprising a set of radio frequency feeds, each feed comprising an amplifying component configured to output a signal that is amplified in power with respect to an input radio frequency signal and a measuring component that outputs a digital signal indicative of radio frequency power detected at the amplifying component, the method comprising:

selecting a frequency from a set of frequencies in a bandwidth of radio frequency electromagnetic waves;

setting a subset of the set of radio frequency feeds to output a radio frequency signal of the selected frequency;

measuring a forward power level for the subset of the set of radio frequency feeds that is outputting the radio frequency signal;

measuring a backward power level for the set of radio frequency feeds; and

processing the measurements of the forward and backward power levels to determine an operating condition of the electromagnetic cooking device based on change of the measurements of the forward and backward power levels over time when a cavity of the electromagnetic cooking device is empty.

2. The method of claim 1 wherein processing the measurements includes modeling the electromagnetic cooking device as a radio frequency network in a multiport configuration.

3. The method of claim 2 wherein modeling the electromagnetic cooking device includes characterizing a set of radio frequency network parameters.

4. The method of claim 3 wherein the set of radio frequency network parameters includes one of S-parameters, Y-parameters, H-parameters or Z-parameters.

5. The method of claim 3 wherein determining the degree of wear or possibility of damage of underlying components includes comparing the set of parameters to a set of parameters previously stored into non-volatile memory.

6. The method of claim 1 further including transmitting the determined operating condition to a device accessible by a maintenance technician.

7. The method of claim 1 further including selecting a phase value from a set of phase values of radio frequency electromagnetic waves.

8. The method of claim 1 further including selecting a power level from a set of power levels.

9. The method of claim 1 wherein the electromagnetic cooking device includes two high-power amplifiers.

10. The method of claim 1 wherein the electromagnetic cooking device includes four high-power amplifiers.

11. The method of claim 1 wherein the set of frequencies ranges from 2.4 GHz to 2.5 GHz.

12. The method of claim 1 where the determined operating condition can indicate one of cavity deformation, door deformation, electromagnetic leakage due to cavity damage, shorted power amplifiers, opened power amplifiers or waveguide damage.

13. The method of claim 1 , wherein the determined operating condition can be one of a normal operating condition, an alert condition or a fault condition.

14. The method of claim 1 , wherein the processing includes calculating a deviation of the ratio of forward to backward power level measurements with respect to an expected ratio of forward to backward power level measurements.

15. An electromagnetic cooking device comprising:

an enclosed cavity;

a set of radio frequency feeds in the enclosed cavity configured to heat up and prepare food by introducing electromagnetic radiation into the enclosed cavity;

a set of high-power radio frequency amplifiers coupled to the set of radio frequency feeds, each high-power amplifier comprising an amplifying component configured to output a signal that is amplified in power with respect to an input radio frequency signal and a measuring component configured to output a digital signal indicative of radio frequency power detected at the amplifying component; and

a controller configured to diagnose the electromagnetic cooking device by:

selecting a frequency from a set of frequencies in a bandwidth of radio frequency electromagnetic waves;

setting a subset of the set of high-power amplifiers to output a radio frequency signal of the selected frequency;

the controller further configured to receive from the power measuring component:

a measurement of a forward power level for the subset of the set of high-power radio frequency amplifiers that is outputting the radio frequency signal;

a measurement of a backward power level for the set of high-power radio frequency amplifiers;

wherein the controller is further configured to process the measurements of the forward and backward power levels to determine an operating condition of the electromagnetic cooking device based on change of the measurements of the forward and backward power levels over time when a cavity of the electromagnetic cooking device is empty.

16. The electromagnetic cooking device of claim 15 wherein the controller is further configured to diagnose the electromagnetic cooking device by:

selecting a phase value from a set of phase values of radio frequency electromagnetic waves; and

selecting a power level from a set of power levels.

17. The electromagnetic cooking device of claim 15 wherein the controller is configured to process the measurements by modeling the electromagnetic cooking device as a radio frequency network in a multiport configuration and characterize the modeled radio frequency network with a set of radio frequency network parameters.

18. The electromagnetic cooking device of claim 17 wherein the set of radio frequency network parameters includes one of S-parameters, Y-parameters, H-parameters or Z-parameters.

19. The electromagnetic cooking device of claim 17 wherein the controller is configured to determine the operating condition by comparing the set of radio frequency network parameters to a set of radio frequency network parameters previously stored into non-volatile memory.

20. The electromagnetic cooking device of claim 15 wherein the controller is configured to determine the operating condition to be an anomalous condition indicative of one of cavity deformation, door deformation, electromagnetic leakage due to cavity damage, shorted power amplifiers, opened power amplifiers or waveguide damage.

21. The electromagnetic cooking device of claim 15 , wherein the controller is configured to determine the operating condition to be one of a normal operating condition, an alert condition, and a fault condition.

22. The electromagnetic cooking device of claim 15 , wherein the controller processes the measurements of the forward and backward power by calculating a deviation of the ratio of forward to backward power measurements with respect to an expected ratio of forward to backward power measurements.