DC 바이어스 된 고주파 Orthogonal fluxgate 센서의 감도와 분해능 = Sensitivity and resolution of orthogonal fluxgate sensor operated with DC biased high frequency excitation

다국어 초록 (Multilingual Abstract)

Orthogonal fluxgate sensor was fabricated with a Co-based amorphous wire with 100 mm-ϕ and a 280-turns pickup coil to investigate the effect of DC bias current ~ 110 mA on its output and/or sensitivity. The operation frequency was varied from 0.8 MHz to 1.4 MHz. DC bias was applied in order to prevent domain wall motion of the magnetic wire and to improve the sensitivity. The sensitivity decreased with excess of DC bias, and the suitable DC bias current is independent on the operation frequency from 0.8 MHz to 1.4 MHz. The output increased with an increasing of operation frequency to reach a peak at 1.2 MHz, but decreased in higher frequencies than 1.2 MHz because of LC resonance of the pickup coil surrounding the magnetic wire core. In order to investigate the frequency dependence of the sensitivity, output spectra of the sensor which was connected by using a coaxial cable with the various lengths of 0.5 ~ 5 m were measured with a RF lock-in amplifier. The maximum sensitivities were obtained at different frequencies according to coaxial cable lengths. It was found that the optimal operation frequencies, at which maximum sensitivities were appeared, were almost identical to the frequencies of impedance resonance. This correspondence could be explained with the maximum power transfer theorem. The experimental results in this study presented the sensitivity was strongly dependent on both DC bias current and operation frequency when the sensor was driven at high frequency ~ 1 MHz. The sensor showed the maximum sensitivity with the DC bias of 20 mA at 1.2 MHz. The high sensitivity of 1.6 V/Oe (=16000 V/T) was obtained.