1992 Fiscal Year Final Research Report Summary
PROPAGATION EXPERIMENT AND THEORY OF THE VLF ELECTROMAGNETIC PULSE WAVE IN THE UNDERGROUND
| Project/Area Number |
03650321
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子機器工学
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| Research Institution | KANAZAWA UNIVERSITY |
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Principal Investigator |
NAGANO Isamu KANAZAWA UNIVERSITY FACULTY OF TECHNOLOGY PROFESSOR, 工学部, 教授 (50019775)
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| Co-Investigator(Kenkyū-buntansha) |
ENDO Koujyo KANAZAWA UNIVERSITY FACULTY OF TECHNOLOGY ASSISTANT, 工学部, 助手 (80242535)
ポール・A・ローゼン 金沢大学, 自然科学研究科, 助手
満保 正喜 金沢大学, 工学部, 教授 (90019696)
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| Project Period (FY) |
1991 – 1992
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| Keywords | VLF pulse generator / SIT / Deep underground / ELF / VLF propagation / EMTD |
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| Research Abstract |
This research has been carried out over two years on the base of following two categories:
1. Design and production of an electromagnetic pulse generator.
2. Experiment and analysis of the wave propagation into the underground.
As for the item 1, we have developed a portable high power VLF pulse generator to transmit a VLF pulse into deep underground. The generator consists of a condenser bank, high-power static induction transistors(SIT) and a circuit to control them. A series of pulses with a current of 1000AT at the frequencies ranging from 100Hz to 100kHz can be generated to drive a loop antenna. The driving current can be raised up to 2000AT by connecting the antenna directly to the condenser bank. As for the item 2, we carried out a propagation experiment of a pulse transmitted from a loop antenna with two turns and a radius of 2m using the pulse generator. The search coil sensor was set at a distance of 30m far from the transmitter and received the resultant pulse wave forms of a direct wave and a reflected wave from underground. We tried to separate a reflected wave from a deep surface under the ground into the resultant wave forms referring the calculated direct wave form from the antenna. The most suitable set up of the transmitter and receiver was discussed to obtain the reflected pulse wave form with better signal to noise ratio from the underground.
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