The Use Of Complex Dielectric Constant As A Diagnostic Tool For The Remote Sensing Of Terrestrial Materials

The Use of Complex Dielectric Constant as a Diagnostic Tool for the Remote Sensing of Terrestrial Materials

A basic problem in remote sensing is to find parameters which can be measured that can lead to a unique signature of given target materials. Two such parameters are the dielectric coefficient and conductivity of the material. In this report the feasibility of measuring the complex dielectric constant of a smooth material from an aircraft or satellite by measuring the refelection of an incident electromagnetic wave is investigated. The results of several experimental approaches to the remote measurement of complex dielectric constant are reported. The methods investigated include X band swept frequency reflectance measurements, dual polarization, and short pulse measurements. For measurements at frequencies above 100 MHz it is shown that the dielectric constant can be determined with plus or minus 10% by measurement of the real part of the complex reflection coefficientto plus or minus 0.3 db. It is further shown that the complex polarization method for determining the complex dielectric constant is not usable for angles of incidence near the normal. (Author).

Scientific and Technical Aerospace Reports

NASA Technical Note