Time domain methods for soil moisture determination

Time domain reflectometry (TDR) is accepted as a valuable tool for measuring soil water content in the agricultural sector. Topp, (1980), has successfully applied the TDR technique to calibrate a wide variety of soils using a Tektronix 1502C cable tester and a two wire waveguide probe embedded in soil samples. The TDR technique measures the relative dielectric constant of a soil sample from which the soil water content can be inferred. In this paper, we examine TDR methods using both a Tektronix 1502C 0-1 GHz tester and an HP 8510C network analyzer over a 0-9 GHz test range. Further, we introduce two time domain transmission (TDT) techniques