Study Of The Coaxial Probe In Measuring The Permittivity Of The RF/Microwave Dielectric

A coaxial probe algorithm that can be used to measure the complex permittivity of dielectric in MW/RF band has been ameliorated in this paper. And the permittivities of some dielecteics in MW/RF band have been gotten by anasysing the two aspects of this method which are load inside and outside.From the symmetry of the coaxial, with the orthogonality of Bessel function and Hankel Transform, the Electromagnetic field in the coaxial was analysised and computed, and the high order TM modes brought by the discontinuity of the prob was known. According to the "mode-matching" method and "phase-matching" method, the effect of some high order TM modes brought by the discontinuity of the dielectrics on the interface in the coaxial cable to the reflectance was demonstrated, and then the link of reflection and permittivity.With the result, the permittivities of some dielectrics such as silicon and Teflon were calculated in and under C waveband. It's found that this algorithm was feasibiable according to compare the nearly identical reference and calculational permittivities of some dielecteics from simulational and computational reflectcnace. And then from the comparison of the coaxial probe algorithm with FDTD, it's found that although the coaxial probe algorithm was more complex than the FDTD, but it was clearer and easier in programming, and the algorithm of FDTD which differents the Maxwell Function was simple but it was complex in programming and the problems such as overflow must be considered.