An adjusting and tuning arrangement is provided in a microwave oven to adjust the energy distribution to various areas of the oven cavity such as defined areas or the area of a sensor assembly on a tray inserted in the oven and also to balance the distribution of energy between the load articles on the tray and the sensor assembly or between various load articles. Two electrically conductive planar elements are positioned inside and project into the cavity to accomplish the tuning. The planar elements are arranged one above the other at predetermined angular orientations and are also each independently rotatable about one edge.