  The low magnetic field measurement has been utilized since ancient times in
order to find economic resources, to detect magnetic anomalies, etc. In this
case, the vector magnetic survey can simultaneously obtain the modulus and
direction information of the magnetic field, which can contribute to obtaining
more precise information and characteristics of magnetic field resources. This
paper is concerned with the possibility of vector magnetic field measurement
with a magneto-inductive (MI) magnetic sensor. To evaluate the capability of
the MI sensor, a test platform is set up and its performance including the
noise floor, the resolution, the sensitivity, etc., are comprehensively
characterized. Further, a comparative geomagnetic observation and magnetic
anomaly detection among the proposed MI sensor, a high-precision Overhauser
sensor, and a commonly used and accepted commercial MI sensor are conducted.
The experimental results identify the capability of the proposed MI sensor in
weak magnetic detection.
