Research And Analysis Of New Series Of Transverse Electromagnetic Cell

The everywhere electromagnetic wave not only interferes with the electronic appliances, but also is harmful to human health. The research on electromagnetic compatibility (EMC) and bioelectromagnetics becomes more and more important. The transverse electromagnetic cell which can establish uniform transverse electromagnetic field , extremely broad band in frequency and arbitrary polarization is indispensable in the EMC test and bioelectromagnetic experiments. Its upper limit frequency of Gigahertz TEM (GTEM) cell can reach to several GHz. However it couldn't change the electric field polarization. Circular TEM (CTEM) cell can provide 0-180 degree field polarization, but its upper limit frequency is only up to several hundred MHz. These characteristics limit their application in EMC test and bioelectromagnetic experiments. A new Taper TEM cell which not only can provide arbitrary polarization field, but also can work up to several GHz is proposed in this paper, it has overcome the structure shortcoming of GTEM and CTEM cell. This paper is mainly focus on the research of Circular TEM cell and Taper TEM cell, furthermore an ellipse TEM cell is proposed in this paper.Firstly, the cut-off frequencies of circular transmission line are calculated by using FDTD method mixed with discrete Fourier transform, the upper limit frequency of circular TME cell can be obtained.Secondly, the CTEM cell with arc inner conductor is proposed. The Characteristics such as field distribution, effective test volume in the symmetrical CTEM cell, asymmetrical CTEM cell, CTEM cell with arc inner conductor are analyzed by FDTD in Circular coordinate. Compared with the other two CTEM cell, More uniform field distribution and larger effective test volume can be provided in CTEM cell with arc inner conductor.Thirdly, The Taper TEM cell is proposed. Symmetrical Taper TEM cell and offset Taper TEM cell are analyzed in spherical FDTD method. The upper frequency limit is determined by analysis the effect of high order modes on field uniform. Its characteristic impedance of taper transmission line is computed by confbrmal transformation method.