マイクロ波測定用プローブを用いたコプレーナ型高周波キャリア型磁界センサの特性評価(センサ・計測)

概要

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Special equipment and measurement circuit structures are needed to characterize the magnetoimpedance effect up to 1 GHz for a high-frequency-carrier type (HFC-type) magnetic field sensor, called a GMI (Giant MagnetoImpedance) sensor. The reason is that accurate measurement of impedance above 100 MHz needs consideration of characteristic impedance throughout the measurement circuit. In this study, a microwave probe of 150 μm distance ground-signal-ground type was used to measure the S11 response of the sensor. For structural conformity with the probe, a coplanar electrode was proposed for the sensor element. The coplanar electrode facilitates construction by a thin film process. This measurement system has excellent repeatability of measurement with short preparation speed. On the other hand, the coplanar electrode of the sensor element has unnecessary electric properties, especially in the high frequency caused by its structure. For example, there are structural inductance and capacitance. We studied the electrical properties of the sensor that are caused by coplanar structure, using computer simulation, and clarified the extent of the unnecessary impedance. Theoretical considerations for estimating the structural effect of impedance were also carried out. It was shown that a simple transmission line equation is in good agreement with the measurement.
社団法人日本磁気学会の論文
2003-04-01