FIG. 2 is a schematic cross-sectional view taken along a section line A-A in FIG. 1. Referring to FIG. 1 and FIG. 2, the cavity 110 may further include a vertical clapboard 111 and a horizontal clapboard 112 for defining an inner space of the cavity 110. The vertical clapboard 111 may be configured to extend from a top plate of the cavity 110 along a vertical direction to a bottom plate of the cavity 110. The radio frequency generation module 130 may be disposed between the vertical clapboard 111 and the rear plate of the cavity 110. The horizontal clapboard 112 may be configured to extend forward from the vertical clapboard 111 along a horizontal direction. The detection module 150 and the load compensation module 160 may be disposed between the horizontal clapboard 112 and the top plate of the cavity 110.
