Recent progress in borehole radars and ground penetrating radars in Japan

This paper describes fundamental system of borehole radars and its recent progress in Japan. Early development of borehole radars were carried out for detection of cracks in crystallized rock, however, the fields of application are expanding to other various objects such as soil and sedimental rocks. Conventionally developed radar systems are not necessarily suitable for these applications and they must be modified. New technologies such as radar polarity and radar tomography were also introduced.