A ceramic substrate composition is provided which can be co-fired with a low-melting metal and exhibits excellent dielectric characteristics at high frequencies, particularly tens of gigahertz. The heater module is furnished with heater part 1a for controlled heating of a wafer placed on its top face, and block part 3a provided to be shiftable relative to said heater part, for varying heat capacity in total with heater part 1a by abutting on or separating from the reverse surface of heater part 1a. The induction coil is positioned so that a center thereof corresponds to a center of the object, and input ends of the coil elements are displaced circumferentially at equal angular intervals calculated by dividing 360\xb0 by the number of identical coil elements. Transformed current is directed to the jaw contacts for metering with the watt-hour meter. The top surface includes a plurality of upward sloping radius blends extending between the substantially planar central portion and a plurality of upward sloping rake faces extending between a respective radius blend and its respective cutting edge such that the rake face forms an angle, A, of between five and twenty-five degrees with respect to the central portion of the top surface. The frequency smearer is provided in order to smear the electromagnetic signal by varying the frequency of the electromagnetic signal across a predetermined frequency band and outputting the smeared electromagnetic signal to an averaging circuit.