Wideband in-situ soil permittivity coaxial probe

A novel probe design form measuring complex permittivity of soils in-situ from 10 to 1000 MHz and above without taking soil samples is presented. The dielectric constant and conudctivity of soil is derived from step-frequency reflection taken inside a small (1~2 inches) freshly bored holes. As a result, permittivity at various depths from surface with in-situ moisture content and soil texture can be obtained in the fields. A novel calibration method was developed to account for the frequency-dependent geometrical factor which causes bias errors in conventional calibration methods. This paper will discuss about the novel probe design and calibration method based on numerical simulation data. We will present the fabricated instrument and measurement examples during the conference.