Target Material Impact on Inductive Sensing Distance Reduction Factors
Target material conductivity and permeability set inductive sensing distance reduction factors, reducing nominal operating range by up to seventy percent.
Quality Factor Attenuation
Signal Decadence
Reduction of the efficiency of a resonant circuit due to energy dissipation in nearby conductive materials is a primary sensing mechanism. Evaluating quality factor attenuation allows an inductive sensor to measure the proximity or thickness of a target. When a metal target enters the coil’s electromagnetic field, eddy currents are generated within it.
This process draws energy away from the resonant tank circuit, which lowers the quality factor of the coil and reduces the amplitude of the output voltage.
Resonant Response
Monitoring the decay of the resonant amplitude provides a direct measure of the energy losses. The sensor circuit converts this quality factor attenuation into an analog voltage or a digital value. This measurement is highly sensitive to the distance and the electrical conductivity of the approaching target.
System Verification
System performance is tested using high-precision LCR meters connected to the sensor coil. These instruments measure the quality factor at the nominal operating frequency both in free space and with the target present.
Temperature Variance
Coil resistance rises with temperature, causing a baseline drop in the quality factor that can mimic a target’s approach. Compensating for this drift requires the integration of a temperature sensor and a correction algorithm. The remaining temperature error must be kept below the calibrated tolerance limit.