Antenna and reader/writer device

Abstract

An antenna for a RFID writer / reader includes a substrate made of a dielectric substance, and a conductor pattern formed on the substrate and including a feeding point, an open end, an extension part extending from the feeding point, and a spiral part extending spirally from an opposite end of the extension part to the open end. The spiral part includes a part juxtaposed with the extension part. A distance along length directions of the conductor pattern, from a zero point at which a current is zero in the part upon feeding power to the feeding point, to a point at which a line perpendicular to the part and passing through the zero point intersects the extension part, is set to a second distance at which an electric field strength generated as a combination of electric fields generated at these points upon the feeding of power enables communications with the wireless tag.

Description

technical field [0001] Embodiments described herein relate to antenna and reader / writer devices. Background technique [0002] Recently, radio frequency identification (RFID) has been widely used as a non-contact automatic identification technology. In radio frequency identification, non-contact data communication is carried out by radio waves between an integrated circuit (IC) tag including a semiconductor memory and a reader / writer device from which the IC Data is read from and written to the tag's semiconductor memory. [0003] A reader / writer device in radio frequency identification includes a communication antenna (reader / writer antenna) that emits radio waves to an IC tag. Such as Figure 13 As shown, a patch antenna including a rectangular conductor pattern 212 for emitting radio waves on a substrate 210 made of a dielectric material is generally used as such a communication antenna. [0004] For example, when such a patch antenna is used to identify the position o...

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Problems solved by technology

[0007] However, for this antenna, if an inexpensive substrate with a low dielectric constant such as an FR-4 substrate is used, it may be necessary to increase the length of the conductor pattern to ensure that the radiated power supplied to the IC tag is large enough, thus increasing the size of the conductor pattern. The size of the pattern in the length direction

The result increases the size of the overall antenna

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