Tag Designs and Techniques Used in HF RFID Item Level Tracking

The tag size will often be a performance issue with use on small products and may also require reorientation of the product and the interrogator antenna which may not be an available option. The current technology of HF tags is focused on the mass production of low cost paper thin tags that have maximized read range performance perpendicular to the broad plane of the tag. These tags are 2D in nature and vary in size dependant upon layout and the chip capacitance of the RFID chip chosen.

An alternative tag that incorporates a ferrite core offers other options in that it allows for maximum read range normal to the small aperture of its geometry. Incorporating both these tag designs for use within the RFID architecture allows for flexibility of product placement and orientation while maintaining optimum performance. A RFID systemi consists of a host system and RF components (Figure 12). The RF components consist of an interrogator (reader and antenna) and tags. The purpose of the interrogator is to communicate to the tags in the field and to also (for passive systems) power the tag through the transmitted RF signal. The interrogator is responsible for;

1. Protocol
2. Tag power
3. Reading tag information
4. Writing tag information
5. Ensure message delivery and validity to host system

The tags are placed on products which the user desires to track. The tag has the capability of storing a unique ID number or user programmed data and can communicate this information to the interrogator. The tag design dictates the limiting parameters of the RFID system such as read range and product orientation.

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