Study on development of the remote electromagnetic wave testing system by micro antenna

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We have developed a novel non-contact electromagnetic NDI system that after applying an alternating current to specimen detected indirectly the changes in the magnetic field generated by the changes in the induced signal flow around a crack with micro antenna (dipole antenna, loop antenna). We have obtained the following knowledge as a result of carrying out a series of measurement in order to obtain the indicator of establishing various parameters to improve the detection sensitivity in the method that the induction wire induces high frequency current was attached to an inspection object and then micro antenna scanned around there.1. To generate the constant existing wave depends on the frequency, the induction wire applied a current and the length of specimen, the frequency reduces this influence exists.2. In this research it is possible to detect the defect with a depth of 1 mm in the case of rift-off 10 mm and it is promising as a remote inspection method.3. We can raise the detect … More ion sensitivity about 30 % as compared with the time of research start by the combination of the length of 15 mm and diameter of 0.26 mm as a result of examination the optimization of micro dipole antenna length and a diameter.4. We can raise the detection sensitivity about 2.3 times as compared with the time of research start as a result of examination the loop diameter of a micro loop antenna.5. It is related with a fatigue crack with a depth of 5.5 mm, the detection sensitivity of a micro loop antenna is about 2.6 times as high as a micro dipole antenna. It is based on the above result ; an antenna sensor combined with an induced wire was developed.6. It is possible to detect the fatigue crack made into the ferromagnetic material and the paramagnetic material by the sensor combined an induced wire.7. Although the signal by developed one apparatus sensor showed the asymmetrical distribution to the symmetrical crack, it is thought that a symmetrical signal distribution is obtained by arranging two for an induced line to an antenna, as a result of carrying out the plane detection of the crack circumference for fatigue crack form measurement.8. A novel non-contact NDI technique that detection of a crack is possible without concerned with the quality of the material was developed. Less