RFID Antennas & Detuning - The RFID Tag Industry Advances

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The job of a system integrator and RFID label manufacturer is to work as a team to deliver RFID labels and tags that best fit the customers application at the minimum total cost of ownership. A conflict can potentially arise if a sales person is tied too closely to one company and tries to bias the customer's decision by recommending a product they sell and that is not optimal for the customer's application.

RFID labels and inlays are designed for specific applications including mounting surface material, read range, chemical and abrasion resistance, adhesive and cost of ownership. If a label falls off the item being tracked, this increases the cost of ownership. If an RFID label doesn't read, this also increases the cost of ownership. If a life of 4 years is needed for an application and the RFID label is incorrectly applied in the wrong location and only reads sporadically, this increases the cost of ownership.

Metalcraft understands the range of rfid applications and works closely with the integrator and customer to test and develop unique labels that meet the customers tracking life expectations, read rate and cost/price criteria. 

Examples of this are the sale of a traditional RFID tag based on a traditional dipole antenna Sold into an application where the tag is mounted close to metal, liquids or on glass. Metals, liquids and metalcontaining glass detune the tag's antenna and shift the frequency response of the tag out of the frequency bands the reader can read the serial number. The symptoms of this detuning by metal and liquids are shorter read ranges, lower read rates and possibly not reading at all.

Industry response to the metals and liquids in the early 2000's was initially to warn customers about this sensitivity and be careful where they place the RFID label. While this is still true today, new patch antennas were developed for UHF RFID tag's that are designed to specifically mount on glass with excellent read range and read rates. These tags were designed with a built in frequency shift to compensate for the detuning effect of glass.

As the demand increased for mount on metal applications, Metalcraft developed a unique non-symmetrical folded patch antenna that contains it's own ground plane, so it truly becomes desensitized to the material the label is applied.

Universal, Mini-Universal, for the North American market, and E-Universal tuned for 865 MHz to 868MHz European RFID frequency bands are UHF RFID tags are specifically designed to mount on metal and provide excellent read ranges and read rates. These tags are location and mounting material independent so they can be mounted anywhere; on cardboard, metal, liquids, plastics or glass and produce excellent results. Because these inlays include a built in ground plane, they are not detuned when mounted on or close to metals like dipole and patch antennas are. One characteristic of a Universal RFID tag is that it is a one-sided read tag because the ground side of the patch antenna is in close proximity to the glass, metal or liquid. The RF signal is reflected to the reader from the ground plane.

RFID is a wonderful technology; it is provides lower overall cost of owner ship for most applications but it requires a longer learning and testing cycle than barcode did in the 80's.

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