Preventive care as well as early detection method and monitoring technique for diseases are highly attracted attention to increase quality of life. Noninvasive measurement method for blood characteristics in body is expected by patients with kidney dysfunction. Complex permittivity of blood is changed a few present at 6GHz. This change is caused by the change of water and albumin contents in blood. In this study, to detect blood characteristics in human body, experiments with phantom model has been performed using thin wideband applicator for examining microwave transmission up to 6GHz. The thin wideband applicator has advantages for detecting living body information in detail. The thin wideband applicator is designed based on Antipodal Vivaldi Antenna and is not required any balun and is very easy handling. Using developed Antipodal Vivaldi Antenna, transmission coefficient can be obtained as a function of thickness of phantom model with high sensitivity. Using this method, highly sensitive sensor for obtaining characteristics of blood in body can be developed.
MRI is applying an electromagnetic (EM) wave for imaging. In application of EM waves, the heating effect will be applicable such as hyperthermia for cancer treatment. This paper examines heating effects of the small resonant devices using Radio Frequency (RF) signal generated by MRI. A small resonant device which is inserted in the body absorbs RF power, and its temperature can be increased. By this method, better heating efficiency and higher transmission properties will be realized. With using a simulator, transmission properties from an RF coil of the MRI to the small resonant device including signal power density and the SAR pattern are evaluated. Transmission properties can be obtained as a parameter of winding number of solenoid coil. In addition, the small resonant device is made on a condition as same as simulation and performed the experiments and measured the temperature rise using an optical fiber thermometer. The experimental results agree well with the simulation. From the results, it is found that the small resonant device is applicable for heating in human body.
To measure the temperature dependent complex permittivity and permeability of materials, measuring systems using cavity resonator in the frequency band of 2.45 GHz have been developed. To measure low loss material with wide temperature range, TE<sub>103</sub> mode cavity resonator system excited by magnetron as power source has been applied. To measure higher loss material with high accuracy, TM<sub>010</sub> mode cavity resonator system excited by solid state power source with vector network analyzer has been applied. By measuring transmission or reflection coefficient of the cavity with measuring the temperature using infrared thermograph, the temperature depending complex permittivity and permeability can be obtained. By using the developed systems, temperature dependent permittivity and permeability for metallic powders and ceramics have been measured and the results are shown in this paper.