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不同煤岩及混合介质中UWB电磁波传播衰减特性试验研究

Experimental study on propagation attenuation characteristics of UWB electromagnetic wave in different coal and mixed media

  • 摘要: 人员搜寻定位是矿山救援的基础,超宽带(UWB)雷达可穿透砖混墙、煤、岩等非磁性介质,实现障碍物后的人员探测定位,超宽带雷达探测技术有望解决矿山遮蔽环境人员探测定位难题。为明晰UWB电磁波在煤岩介质中的衰减特性,基于电磁波传播理论,推导得出煤岩介质中电磁波有效传播距离和衰减系数计算式,得出有损介质环境中的UWB电磁波衰减系数与介质相对介电常数、电导率成正相关。并利用射频信号衰减系统开展UWB电磁波在4种厚度(30、60、90、120 cm)的褐煤、瘦煤、砂岩、石灰岩及煤岩混合(混合比例3∶7、7∶3)介质中的传播衰减试验。试验结果表明:① UWB电磁波能量均随着煤岩介质厚度的增加而减小,介质中电磁波能量幅值波形会产生多次间隔接近的振荡,且减小幅度依次降低,表明UWB电磁波能量衰减与煤岩介质厚度成正相关。② 煤岩分层混合介质中的电磁波能量衰减取决于煤、岩介质的衰减和煤、岩占比情况,电磁波在煤岩混合介质中的衰减近似于单一煤、岩介质的衰减叠加,具体为穿透分层混合煤岩介质的电磁波衰减程度与电磁波在煤、岩单一介质中的衰减程度及煤、岩占比成正相关。③ UWB电磁波能量峰值随煤岩厚度增加往低频区域偏移。不同厚度下,穿透煤岩介质的UWB电磁波均有对应低频频率的能量峰值,其中穿透120 cm瘦煤及瘦煤砂岩、瘦煤石灰岩混合介质的UWB电磁波在低频区和中心频率处出现2个相同峰值的波峰,说明在衰减幅度较弱的煤岩介质中存在多个最佳探测频率。试验结果可为面向矿山救援的UWB雷达生命信息探测技术相关基础研究及设备研发应用提供借鉴。

     

    Abstract: Personnel search and localization constitute the fundamental aspects of mine rescue operations. Ultra-Wide Band (UWB) radar technology possesses the capability to penetrate non-magnetic media, including masonry walls, coal, and rock, thereby enabling the detection and localization of individuals beyond physical obstructions. It is anticipated that UWB radar detection technology will address the challenges associated with personnel detection and localization within sheltered mine environments. In order to clarify the attenuation characteristics of UWB electromagnetic wave in coal and rock medium, based on electromagnetic wave propagation theory, the effective propagation distance and attenuation coefficient of electromagnetic wave in coal and rock medium are derived, and it is concluded that the attenuation coefficient of UWB electromagnetic wave in the environment of lossy medium is positively correlated with the relative dielectric constant and conductivity of medium. And utilize the RF signal attenuation system to carry out the propagation attenuation test of UWB electromagnetic wave in four thicknesses (30, 60, 90, 120 cm) of lignite, lean coal, sandstone, limestone and coal-rock mixing (mixing ratios of 3∶7 and 7∶3) media. The test results show that: ① UWB electromagnetic wave energy are reduced with the increase of the thickness of the coal rock medium, the electromagnetic wave energy amplitude waveform in the medium will produce a number of intervals close to the oscillation, and the reduction in the magnitude of the sequential decrease, indicating that the UWB electromagnetic wave energy attenuation is positively correlated with the thickness of the coal rock medium. ② The attenuation of electromagnetic wave energy in coal and rock stratified mixed media depends on the attenuation of coal and rock media and the ratio of coal and rock, the attenuation of electromagnetic wave in coal and rock mixed media is similar to the superposition of the attenuation of a single coal and rock media, which is positively correlated to the degree of electromagnetic wave attenuation penetrating the stratified mixed coal and rock media with the degree of attenuation of electromagnetic wave in a single medium of coal and rock, as well as the ratio of coal and rock. ③ The energy peak of UWB electromagnetic wave is shifted to the low-frequency region with the increase of coal rock thickness. Under different thicknesses, the UWB electromagnetic wave penetrating the coal-rock medium has energy peaks corresponding to the low-frequency frequency, in which the UWB electromagnetic wave penetrating the 120 cm lean coal and lean coal sandstone, lean coal limestone mixed medium has two peaks with the same peaks in the low-frequency region and at the center frequency, which indicates that there are multiple optimal detection frequencies in the coal-rock medium with a weak attenuation amplitude. The test results can provide a reference for the basic research related to UWB radar life information detection technology and equipment development and application for mine rescue.

     

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