Optimization and design of wide-band and low-noise air-core coil sensor for TEM system

Abstract

The effective bandwidth and background noise of the sensor are important factors to the performance of TEM, especially in the detection of urban underground space. The limitation of the size of coils further reduces the bandwidth and sensitivity of the sensor, resulting in the distortion of high-frequency signal from ultra-shallow and the loss of weak signal from deep. In order to solve this problem, by establishing the physical model of the induction air-core coil sensor, a method of winding wire which reduces the parasitic parameters of the air-core coil is proposed to improve the bandwidth and sensitivity of system. Combined with theoretical simulation, the components of noise and parasitic parameters of the air-core coil sensor were analyzed, and the system was optimized. An air-core coil sensor with an effective bandwidth of 783 kHz and an equivalent noise of about 2.45 nV/ Hz was obtained. The new sensor effectively improves the detection capability of TEM system for high-frequency secondary field signal, which has positive significance for the application of TEM in urban underground space.