Linearly reciprocating tray for microwave oven

A microwave oven comprising:

• a cooking chamber having a bottom plate;
• a tray linearly traveling in the cooking chamber;
• a motor providing driving force necessary for the movement of the tray;
• a support disposed between the bottom plate and the tray to support the tray;
• at least one guide structure formed at the bottom plate to guide a movement of the support;
• an oval guide hole formed through the support, the guide hole having a first radius in a major axis direction and a second radius in a minor axis direction;
• and
• a linkage to receive the driving force from the motor so that the linkage rotates within the guide hole,
• wherein the linkage has a rotation radius larger than the second radius of the guide hole, to linearly move the support while being in contact with an inner surface of the guide hole, and the first radius of the guide hole is larger than the rotation radius of the linkage, to allow the linkage to rotate freely in a state of being spaced apart from the inner surface of the guide hole, and
• the support linearly travels between a first position and a second position along right and left directions and the linkage is separated from the inner surface of the guide hole when the support reaches the first position or the second position, to allow the support to stop at the first position or the second position for a predetermined time.