Abstract: In a cooking appliance, the foodstuff is placed on a turntable in a heating chamber. Infrared radiation emitted from the foodstuff is sensed by an infrared sense unit. The cooking appliance obtains the number of extrema of the amount of infrared radiation sensed over the period of one cycle of the turntable. The number of foodstuffs is determined according to the number of maxima. A control unit drives a heat unit according to the determined number of foodstuffs.

Abstract: A microwave oven includes a cavity in which food is accommodated, a magnetron for generating microwaves, and a waveguide to supply microwaves generated from the magnetron into the cavity. The waveguide has substantially a truncated cone configuration in which the cross sectional area at the cavity side is greater than the cross sectional area at the magnetron side, and an output antenna of the magnetron is disposed to project from the bottom of the waveguide at the magnetron side into the inner space of the waveguide. The microwave oven further includes a flat radiation antenna fixed in the inner space of the waveguide around the output antenna of the magnetron while maintaining distances from the waveguide and the output antenna of the magnetron in which no spark is generated. Therefore, the radiation area for emitting the microwaves is increased significantly to improve heating nonuniformity within the cavity.