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PROPAGATION EXPERIMENT AND THEORY OF THE VLF ELECTROMAGNETIC PULSE WAVE IN THE UNDERGROUND

甚低频电磁脉冲波在地下传播实验与理论

基本信息

批准号：
03650321
负责人：
NAGANO Isamu
金额：
$ 1.34万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650321/
关键词：
VLF pulse generator SIT Deep underground ELF VLF propagation EMTD ULF 大振幅電磁パルス

项目摘要

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.

本研究经过两年多的时间，主要分为以下两类： 1．电磁脉冲发生器的设计与制作；2．波向地下传播的实验与分析。对于第1项，我们开发了一种便携式高功率VLF脉冲发生器，用于将VLF脉冲发射到地下深处。该发生器由电容器组、大功率静电感应晶体管（SIT）和控制它们的电路组成。可以产生频率范围为100Hz至100kHz、电流为1000AT的一系列脉冲来驱动环形天线。通过将天线直接连接到电容器组，驱动电流可提高至2000AT。对于第2项，我们使用脉冲发生器对半径为2m的两匝环形天线发射的脉冲进行了传播实验。搜索线圈传感器设置在距离发射器30m远的地方，接收来自地下的直达波和反射波的合成脉冲波形。我们尝试将来自地下深处的反射波分离成合成波形，参考计算出的天线直达波形。讨论了最合适的发射器和接收器设置，以获得来自地下的具有更好信噪比的反射脉冲波形。