Radio frequency identification is creating big changes in the way companies handle product tracking, security, authentication, and more. Find out how the technology works and why screen-printing shops are in a great position to stake claims in RFID manufacturing.
By Wim Zoomer
The read range of RFID tags varies, depending on the application. RFID tags with a range of just a few millimeters can be embedded in banknotes and vouchers for sorting and authentication. For logistics, a range of 3 m often is required to read many tags simultaneously. Road tolling requires read ranges of up to 100 m or more. The type of RFID tag, the antenna it uses, and the source of its power all influence the read distance.
RFID tags can be either active or passive. Active tags are provided with an internal, ultra-thin battery and contain either a read-only computer chip or a chip that data can be read from and written to by the reader. This type of label, known as a two-way tag, typically has the greatest data capacity. When used in production environments, such labels can be attached to items being manufactured and used to transmit instructions to machinery and receive data throughout the manufacturing process.
Passive tags function without a battery. One form of passive tag reacts to radio waves much like an active tag. The tag takes a small portion of the energy from the reader’s original radio signal and reflects it back as a modulated signal. The modulated signal is encoded with the data stored in the tag. Referred to as back-scatter tags, such tags are often used in license plates and return a unique signature that allows the reader to recognize the plate from a database of licenses.
The type of antenna used in the tag and the frequency of the signal also influence the read distance.The frequencies used by passive RFID systems commonly fall into one of the following ranges:
• low frequency (125-135 KHz): read distance approximately 0.5 m; used in tagging livestock, product authen- tication, access control
• high frequency (13.56 MHz): read distance under 1 m; used in credit cards, laundry tickets, library books
• ultra-high frequency (868-930 MHz): read distance up to 3 m; used in product distribution and logistics applications, baggage handling, and toll collection
• microwave (2.45 GHz or 5.8 GHz): read distance approximately 1 m; used primarily in toll collection and baggage handling
Manufacturing RFID antennas
Manufacturing the antenna is the initial step of the production process. One of three different methods is typically used to produce antennas, particularly those for high-frequency and ultra-high-frequency applications:
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