Satoshi Ogino

Development of Optically Transparent Ultrathin Microwave Absorber for Ultrahigh-Frequency RF Identification System

The application of UHF radio-frequency identification (RFID) systems is rapidly increasing. However, the reliability of indoor telecommunication is adversely affected by multiple reflection interference. Consequently, to establish a highly reliable UHF-RFID system, it is essential to improve the multipath environment. This paper describes an ultrathin microwave absorber that is designed to improve the multipath environment of UHF-RFID systems. This absorber is optically transparent so that it does not create blind areas for surveillance cameras installed near an UHF-RFID system (e.g., at the entrance of an office or a warehouse). The improved tag identification probability using this absorber is demonstrated in an actual warehouse.

Optimize pattern of magnetic sheet attached on NFC/HF-RFID antenna

When a payment system with NFC/HF-RFID is installed in smart phone, their communication with 13.56 MHz is blocked by such metal as battery, coil and PCB. To solve this problem, magnetic sheet with high permeability is set between NFC/HF-RFID antenna and near-by metal. So far thin compound magnetic sheet or thin sintered ferrite has been used. In order to make thickness of these materials thinner, we propose amorphous magnetic sheet. Besides this amorphous magnetic sheet causes to increase the transmission effect.

Study on the effective loading shape of magnetic sheet for receiver coil in WPT systems

Recently, Wireless Power Transmission (WPT) system in accordance with Qi standards is being installed into smartphones. However, the transmission efficiency is greatly deteriorated due to adjacent metal objects. To solve those problems, it is thought that the high permeability magnetic sheet insertion method into the gap between WPT-coil and metal objects is effective. On the other hand, the high permeability magnetic sheet (for instance, an amorphous magnetic sheet) has large loss as a negative feature. Therefore, to improve transmission efficiency of the WPT systems, and to suppress thickness of these materials, the magnetic loss control by trimming of the amorphous magnetic sheet is proposed in this report.

Study on effective pattern of magnetic sheet attached on NFC antenna

In case of payment system with NFC (Near Field Communication)/HF-RFID (Radio Frequency IDentification) installed into the smart-phone, NFC antennas communication performance at 13.56MHz is deteriorated by the battery case or circuit boards. To solve this problem, the magnetic sheet with high permeability is inserted into the NFC/HF-RFID antenna and metal object. Thin magnetic compound or sintered ferrite has been used as the high permeability sheet. However, these sheet thickness could not be suppressed to improve the NFC/HF-RFID antennas performance. In order to make thickness of these materials thinner, we propose amorphous magnetic sheet. Besides because the loss of amorphous magnetic sheet is large, that loss suppression technique is also proposed.