ECCOPAD® Frequently Asked Questions
Why don’t RFID tags work on metal?
How does ECCOPAD® work?
Does ECCOPAD® work on liquids?
Why does ECCOPAD® have a white side and a gray side?
Why is there a different isolator for every different tag?
Why is there no ECCOPAD® isolator for the (insert tag name here)?
Does the size of the isolator matter?
Does the size of the object to be tagged have an effect?
Will I get the same read range with ECCOPAD on metal as in free space?
Why don’t RFID tags work on metal?
RFID tag antennas are designed to efficiently receive energy transmitted from the reader. Since a passive RFID tag has no power source, it must derive all its power from the incoming wave. If this energy is not transferred to the chip efficiently the chip will not power up and the tag won’t be read. A well designed RFID tag antenna is said to be ‘tuned’ to the reader frequency and presents a good ‘match’ to the incoming energy. In proximity to metal or liquids or other high dielectric materials, the tag antenna becomes detuned which results in a mismatch which means it will no longer efficiently transfer power to the chip at the reader frequency. Hence greater transmit power is necessary to read the tag. This results in deteriorated read range.
How does ECCOPAD® work?
An RFID tag antenna is influenced by the electromagnetic properties of the substrate on which it is placed. If the substrate is low dielectric materials such as cardboard or wood, there is little or no noticeable effect. Through intelligent selection of the electromagnetic properties of the ECCOPAD® materials, the tag antenna can be retuned to its desired frequency when placed on metal. Emerson & Cuming Microwave Products has been granted Patent #7,205,898 for the design of ECCOPAD® UHF. ECCOPAD® UHF is unique in that it uses material with magnetic properties (magnetic permeability) to achieve isolation. A thin low loss dielectric spacer is used to fine tune the performance
Does ECCOPAD® work on liquids?
ECCOPAD® isolators are designed with specific electromagnetic properties at specific thicknesses and depend on a metal substrate. For use on liquids, a thin metal ground plane is added to the back of the isolator.
Why does ECCOPAD® have a white side and a gray side?
RFID tags are designed to perform on low dielectric substrates. The gray side has magnetic properties which is key to the isolation properties. The white side is a pure dielectric layer which serves to fine tune isolator performance. The tag must be mounted on the white side while the gray side goes against the metal.
Why is there a different isolator for every different tag?
Design of an RFID tag includes a balance of different performance issues often at odds with each other. These issues include chip impedance, read range, omni-directionality, size, substrate, cost, etc. This results in many different tag designs, each somewhat unique in their electrical properties and their susceptibility to nearby metal and liquids. Since each tag has different properties, the ECCOPAD® isolator for each tag type will be unique. In general, an isolator designed for one RFID tag will not work with another tag.
Why is there no ECCOPAD® isolator for the (insert tag name here)?
In some cases it is due to the fact that we have not tested that tag. In many cases we have tested the tag and have not yet produced a working design. Due to various technical issues with some tags, an ECCOPAD® isolator is not possible.
Does the size of the isolator matter?
The isolator should be larger than the tag antenna to maximize read range. How much larger is dependent on the tag.
Does the size of the object to be tagged have an effect?
Yes. An RFID tag communicates with the reader through the backscatter or reflection off the tag. It does so by modulating the tag antenna impedance which changes the tag's radar cross section (size of the reflection). The reader detects the amplitude modulated signal. A large piece of metal has an extremely large radar cross section which will tend to drown out the much smaller signals from the tag. This effect can be mitigated somewhat by reading the tag at an angle that minimizes the reflection return from the object e.g. at 30-45 degrees from the perpendicular.
Will I get the same read range with ECCOPAD® on metal as in free space?
Probably not. ECCOPAD acts as a band-aid to retune the tag antenna. Performance is generally 50-60% of the free space read range.
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