A six-port based on-line measurement system using special probe with conical open end to determine relative complex permittivity at radio and microwave frequencies

Upon using reflection method, a special probe: a coaxial line with conical open end is applied to measure the complex relative permittivity of lossy materials at radio and microwave frequencies. We study the probe from the antenna aspect to find a theoretical relation between the reflection coefficients and relative complex permittivity of dielectric materials. The analytical impedance modeling is established. Theoretical simulations on several dielectric materials given by this new impedance modeling method show improved results. A portable complex relative permittivity measurement system with wide band, high accuracy, low cost etc., is fabricated. In this on-line measurement system, a new six-port junction in MIC (microwave integrated circuit) is used in order to realize the reflection method mentioned above. For this new six-port junction, a new method for linearizing the diodes is carried out. Then in the subsequent calibration procedure for the six-port junction, the criteria error function is modified. The using of six-port junction to measure the reflection coefficients reduces the cost of components needed for the usual frequency conversion methods which are used in commercial network analyzer. Since we use diodes to detect the out-put power of the six-port junction instead of the power meter. It reduces again the cost of the reflectometer. We suppose this on-line measurement system is useful in many domains of applications