[Show abstract][Hide abstract] ABSTRACT: The specific absorption rate (SAR) is an indicator of the thermal effects caused by microwave exposure in biological tissue. Conventionally, an electric field probe scanning method is used for SAR evaluation. Although many countries have confirmed the validity of the electric field probe scanning method used in many SAR evaluation devices, a comparison between physically different measurement techniques is an important goal for validating a standard and for evaluating the uncertainty of a measurement system. Hence, the authors developed a thermal SAR measurement method using an optical fiber thermal sensor. In this paper, the results of comparison measurements between the electric field probe scanning system and the proposed thermal SAR measurement system are presented. The results show that the SAR measurements by each system overlap within the range of the expanded standard uncertainty in the frequency range of 2–6 GHz.
No preview · Article · Feb 2012 · IEEE Transactions on Instrumentation and Measurement
[Show abstract][Hide abstract] ABSTRACT: The specific absorption rate (SAR) is an indicator of the thermal effects caused by microwave exposure in biological tissues. Electric field probe scanning has been used as a practical SAR evaluation technology until now. A measurement standard is necessary for any physical quantity. In general, the existence of a standard constructed with a physically different procedure is important in uncertainty evaluation of the measurement standard. In this paper, a thermal SAR measurement method using an optical fiber thermal sensor is proposed. The thermal SAR measurement method is not suitable for dosimetric assessments for an actual cellular phone. Nevertheless, the proposed method is a simple measurement technique for measuring the temperature rise caused in an equivalent biological tissue (semisolid phantom) by electromagnetic energy absorption. A thermal sensor works independently of the frequency and is, therefore, suitable for primary testing of an electric field probe scanning system. The measurement utility of the proposed thermal SAR measurement method was verified in this paper. The results show that the proposed method is able to measure SAR within an error range of 1%-3% above 2 GHz.
No preview · Article · Jul 2010 · IEEE Transactions on Instrumentation and Measurement
[Show abstract][Hide abstract] ABSTRACT: Recently, radio-frequency identification (RFID) has been gaining interest as a distribution management system to replace bar codes. An important difference between the RFID system and the bar code system is that, in the former, data are changeable by remote control. A system for managing gathered tags (13.56 MHz carrier wave) and a system for long-distance identification (953 MHz carrier wave) are now suitable for practical use. For continuous operation, these must integrate seamlessly. However, some disadvantages exist in long-distance identification with the 13.56 MHz carrier wave systems. To identify a gathered tag accurately, mutual interference must be suppressed. Therefore, we developed a novel emission device based on the coaxial cable leakage of a railway cellular phone service. Specifically, multiple small slots are opened on a flat shielded microstrip line. The result of an investigation into the optimum slot shape to suppress mutual interference is reported here. It is also experimentally confirmed that the proposed system can accurately identify gathered tags.
No preview · Article · Jan 2010 · IEEJ Transactions on Electronics Information and Systems
[Show abstract][Hide abstract] ABSTRACT: In this paper, the development of a small antenna that can tune by broadband or two or more bands is described. The concrete specification which this antenna should satisfy, is that VSWR becomes 2.5 or less in the UHF band (470-700 MHz) which one-segment broadcasting service of digital terrestrial TV broadcasting of Japan uses. Concretely, the method of separately setting up the tuner probe in L-shape probe feed PIFA (planar inverse F shape antenna) is tried. As a result, the control bias for the tuner probe need not be superimposed to the antenna feed point, and the convenience of the antenna has improved greatly.
[Show abstract][Hide abstract] ABSTRACT: Recently, radio frequency identification (RFID) system is noticed as a distribution management system that replaces the bar code. The system for conglomerate tag management (at 13.56 MHz) and the system for the long distance identification (at 953 MHz) have been carried out to practical use now. For continuous logistics, these requested to be integrated seamlessly. However, integration into the system, which uses the frequency band of 13.56MHz, is disadvantageous to leave the feature of the long distance identification. In this report, the system, which adequately identifies conglomerate tags by the frequency band for the long distance identification is described.
[Show abstract][Hide abstract] ABSTRACT: Wireless telecommunication devices such as mobile phones, wireless LANs (2.45 GHz, 5.2 GHz) and UHF radio frequency identification (UHF-RFID) systems have proliferated all over the world. Therefore, electromagnetic interference (EMI) problems have increased. In indoor use, the wireless telecommunications environment can deteriorate due to multiplex reflection interference. This interference must be suppressed to improve wireless communications. Therefore, establishment of a multiplex reflection interference suppression technology is needed. In this study, a convenient, thin EM wave absorption wall was developed. The practicality of this wall was verified through the experimental results of a prototype absorption wall and the calculated results of a finite-difference time-domain (FDTD) numerical analysis. The proposed thin EM absorption wall and the verification results are described in this paper.
[Show abstract][Hide abstract] ABSTRACT: It is necessary to establish the experimental evaluation technique of the specific absorption rate (SAR). Practicable SAR evaluation technique has the electric field probe scanning method. However, it is thought that the SAR evaluation by a physically different approach is necessary for the estimation of the uncertainly in the SAR measurement method. Therefore, in this paper, the thermal SAR evaluation method with the optical fiber thermometer is proposed. In addition, a comparison measurement result for SAR by the thermal evaluation method and DASY3 is being described.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a simple shape planar antenna with high adaptability to an Radio Frequency IDentification tag. The feed point of this antenna consists of two adjacent electrodes in the plane which can be matched to the intrinsic impedance of a coaxial cable (50-Ω) without using parasitic elements or balun. Specifically, the aperture shape inside the loop antenna is modified without deforming the antenna element outline. Control of the input impedance becomes possible and bandwidth for S11≤-10 dB can reach about 49% of the central frequency. The proposed antenna demonstrates a steady gain (3.5-4.2 dBi) within a wide frequency range. An investigation of antenna-element miniaturization showed the sectional area of the antenna element could be compressed by about 50% while maintaining wide bandwidth.
No preview · Article · Jul 2006 · IEEE Transactions on Antennas and Propagation