Microwave oven interference on wireless LANs operating in the 2.4 GHz ISM band

Commercial microwave ovens as applied in restaurants have two magnetron tubes and compared to domestic kitchen counterparts they spread the higher RF power and radiated heating energy more evenly. The domestic kitchen or residential microwave ovens have only one magnetron tube. The interference from the commercial type of microwave ovens is more difficult to characterise than the interference from the residential ones. The commercial type of microwave ovens radiate a CW-like interference that sweeps over tens of MHz during the two bursts per mains power cycle. The residential ones give a CW-like interference that has a more or less stable frequency near 2.45 GHz occurring once per mains power cycle. The impact of the interference from the commercial type of microwave ovens on wireless LANs conforming the IEEE 802.11 standard for both DSSS (direct sequence spread spectrum) and FHSS (frequency hopping spread spectrum) has been evaluated.