Abstract: A microwave oven antenna having a three-dimensional motion. A vertical shaft has a microwave antenna coupled to a first end and is attached at a second end to a first driven gear. A cam follower member extends from the first driven gear to engage with a second driven gear having a slanted surface. The first and second driven gears are coupled to first and second drive gears by respective drive belts, such arrangement providing independent rotation to the first and second driven gears. Either the first and second drive gears or the first and second driven gears are of different diameter so that the relative motion of the gears provides the antenna in a different rotational position after consecutive vertical excursions. With this arrangement, the uniformity of heating food products in a microwave oven is improved by increasing the randomness of the mode pattern.