Electrical characteristics of and E-field distribution in CTL (Coupled-transmission-line) cell for SAR measurement probe calibration at 150 MHz

Many countries are regulating rf absorption of mobile terminals because of possible hazardous effect by wireless handsets. S. Korean government made public for the first time in the world that 150 MHz portable radio transceiver shall be regulated by SAR. So it needs to develop calibration system of SAR measurement for 150 MHz band. It includes to produce semi-uniform E-field and H-field in an appropriate volume to calibrate the SAR measurement probe. CTL cell was developed for this purpose and tested to check its validity to calibrate the probe. E-fields in air and in the human simulating liquid in the developed CTL cell were measured. It was verified that uniform field in the cell was excited in air. Although E-field distribution in the simulant liquid was nonuniform by the long distance, but the cell gives uniform enough space for calibrating a SAR measurement probe in the short distance.