PRACTICAL CONSIDERATIONS FOR USING A TDR CABLE TESTER

被引：57

作者：

CASSEL, DK

KACHANOSKI, RG

TOPP, GC

机构：

[1] Department of Soil Science, North Carolina State University, Raleigh

[2] Department of Land Resource Science, University of Guelph, Guelph

[3] Land Resource Division, Center for Land and Biological Resources Research, Agriculture Canada, Ottawa

来源：

SOIL TECHNOLOGY | 1994年 / 7卷 / 02期

关键词：

TIME DOMAIN REFLECTOMETRY (TDR); TDR CABLE TESTER; SOIL WATER CONTENT;

D O I：

10.1016/0933-3630(94)90013-2

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

Time domain reflectometry (TDR) technology can be used to measure soil water content, but due to an incomplete understanding of this technology, some scientists are still reluctant to adopt it. The objectives of this paper are to discuss the basic principles of TDR to measure soil water content, to present the equations to convert TDR screen readings to soil water content values, and to describe a custom built TDR system. Commercial cable testers operate under the assumption the dielectric constant of the medium is known. For soils applications the dielectric constant varies with soil water content and is unknown. The equations which govern the TDR technology presented in logical order allow the user to understand the relationships between wave velocity, dielectric constant, and soil water content. The custom-built TDR system described herr uses a commercially available cable tester; a balun transformer, shielded, two-wire transmission cable; and wave guides constructed from stainless steel welding rod. Several of these systems have been successfully used for six years.

引用

页码：113 / 126

页数：14

共 31 条

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