COMPARISON OF TIME-DOMAIN REFLECTOMETRY PERFORMANCE-FACTORS FOR SEVERAL DIELECTRIC GEOMETRIES - THEORY AND EXPERIMENTS

We propose three nontraditional dielectric geometries and present an e xperimental and theoretical analysis and comparison of time domain ref lectometry (TDR) performances for them. The traditional geometry (the probes inserted in material of essentially infinite extent) is compare d to three nontraditional geometries where the probes are affixed outs ide of a core sample, inside of a bore, or flat on the surface of a se mi-infinite solid. Our derivation relates the velocity of electromagne tic wave propagation to the complex permittivities and permeabilities of the media and the geometry for the three nontraditional configurati ons. Experimental results for air, styrofoam, dry sand, wet sand of va rying water content, nylon, dry wood, and ferromagnetic steel are obta ined for the three proposed configurations and are in fair agreement w ith the literature within the experimental uncertainties. Through expe riments and theoretical analysis, the TDR performance is found to be t he same within the experimental uncertainties for the three nontraditi onal geometries. The proposed geometries yield slightly lower sensitiv ities compared to the traditional geometry. Advantages and disadvantag es of the geometries compared to the traditional geometry are also dis cussed.