Abstract: A portable microwave measurement instrument is disclosed for measuring an unknown property of a test material, such as moisture content, by generating and transmitting two microwave beams of different frequency through such material so a portion of the beam energy is absorbed by the moisture. The corresponding attenuated received signals are compared in order to compensate for the presence of a component in the test material, which is not being measured but which also absorbs microwave beam energy. A temperature compensation circuit using two thermistors is connected to the PIN diode attenuators to adjust their attenuation characteristics in compensation for changes in temperature. To determine the density of the test material, one of the microwave signals is used to measure the phase shift of the corresponding received signal and produce a phase shift output signal.

Abstract: A microwave measurement apparatus is disclosed for measuring an unknown property of a test material, such as moisture content, by transmitting microwave beams through such material so that a portion of the beam energy is absorbed by the moisture or other property. Two microwave input signals of different frequencies are used to form the microwave beams and the corresponding attenuated received signals are compared in order to compensate for the presence of a component in the test material, such as foundry molding sand, which is not being measured but which also absorbs microwave beam energy. To determine the density of the test material in the event of changes in such density, one of the microwave signals is used to measure the phase shift of the corresponding received signal and produce a phase shift output signal.

Abstract: A microwave measurement apparatus is disclosed for measuring an unknown property of a test material, such as moisture content, by transmitting microwave beams through such material so that a portion of the beam energy is absorbed by the moisture or other property. Two microwave input signals of different frequencies are used to form the microwave beams and the corresponding attenuated received signals are compared in order to compensate for the presence of a component in the test material, such as foundry molding sand, which is not being measured but which also absorbs microwave beam energy. To determine the density of the test material in the event of changes in such density, one of the microwave signals is used to measure the phase shift of the corresponding received signal and produce a phase shift output signal.

Abstract: Apparatus is disclosed for measuring the moisture content of a moving layer of particulate material carried on a conveyor by transmitting a beam of microwave radiation through such layer. A portion of such microwave beam is absorbed by the water in the particles and the unabsorbed portion is detected to determine the moisture content. A layer leveling means including a rotating endless flexible leveling belt engaged by a pressure roller, contacts the top surface of the particulate layer to level the thickness of such layer upstream of the measuring position, thereby enabling more accurate measurement of its moisture content. The height of the pressure roller above the conveyor is adjusted in response to changes in the thickness of the layer being measured.