1. Field of the Invention
The instant disclosure relates to an antenna; in particular, to a near field antenna for object detecting device.
2. Description of Related Art
The radio frequency identification tag (RFID tag) is utilized to be installed to an object for being detected through electromagnetic wave of wireless sensing means, which provides a fast and accurate detecting result. The application may be warehouse management or logistics for example. Radio frequency identification is a wireless communication technology which utilizes a reader and a tag to constitute a RFID system. The RFID reader transmits radio waves, and the RFID tag generates electric current according to electromagnetic induction of the radio waves. The generated electric current is for the operation of the chip (or integrated circuit) in the RFID tag and the RFID tag transmits electromagnetic wave responding to the RFID reader.
The RFID reader is usually designed to detect and read the RFID tags as more as possible. Thus, the near field antenna is usually designed to detect all RFID tags in the predetermined reading space, for example, the RFID tags at different locations and located in different directions could be detected (or read). Accordingly, it raises an issue that the conventional RFID reader could not determine the distance and location of the read RFID tags.