10-Mbps Short-Range Baseband Wireless Communications via Quasi-Static Electric Fields

We propose a novel short-range wireless communications technology that uses quasi-static electric fields; it enables data communication between devices separated by up to 10cm via dielectric media at a speed of 10Mbps. It is considered to be a secure wireless technology since communication area is restricted to below about 10cm. To suppress electromagnetic radiation, we adopted a baseband transmission scheme in which the quasi-static electric field is directly modulated by 10BASE-T data signals. Since the spectra of the data signals are concentrated to below 20MHz, the amplitude of the electric field rapidly decreases outside the communication area. This contributes to enhancing security of the communications system. In this paper, we explain a basic principle of the short-range wireless communications technology. Since baseband data signals are carried by the quasi-static electric field, the quality of the communication is easily degraded by the existence of the earth ground. To isolate the communications system from the earth ground, we introduce a novel electro-optic sensor to receive the quasi-static electric field. With the electro-optic sensor, stable data communication is possible at 10Mbps via dielectric materials, such as a wooden table.