Patent ID: 7012228

Claim:
A microwave oven comprising a magnetron for delivering microwave power to a cavity of the oven, a rotatable phase modulator for preventing the establishment of dominant standing waves in the cavity, and a forced hot air system comprising an electrical resistance heater and a rotatable fan for forcing air over the heater and through the cavity, wherein the phase modulator and the fan are mounted on a common driveshaft which extends through a launch box by means of which microwave power is delivered from the magnetron to the cavity, wherein the phase modular has blades extending from one or both sides of a disc-like plate disposed in a plane perpendicular to the rotational axis of the shaft, and wherein the disc-like plate is spaced from the internal surface of the outer wall of the launch box by a distance corresponding to a quarter wavelength at the operating frequency of the magnetron and wherein the fan also has blades extending from one or both sides of a disc-like plate disposed in a plane perpendicular to the rotational axis of the shaft, and wherein the respective planes of the disc-like plates of the modulator and the fan are spaced by distance corresponding to a quarter wavelength, the fan being further away from an outer wall of the launch box than the phase modulator.