Trolley Scan(Pty) Ltd
"EcoTag might be one of the
most significant enabling developments in Radio Frequency Identification
in the last ten years."
Impact of Transponder sensitivity on
- EcoTag is a patented new
technology developed by Trolley Scan which dramatically increases the
efficiency of power conversion in a passive transponder. This increase
in performance been measured in excess of 200 times over conventional performance.
This has major impact on the use of transponder systems in regions where
regulations restrict the power allowable for transponder systems, on the
power needed from the reader to energise transponders and on the operating
range of the transponder.
- EcoTag was specifically
born from the requirements expressed by Trolleyponder's European licensees,
due to the severe limitations placed on RFID readers due to their regulations.
While competitive products battle to achieve 30cms, an EcoTag version
can be read over many meters despite it being a passive tag.
- EcoTag variants of Trolleyponder®
exhibit the same properties as the base technology, their antenna systems
have the same radiation patterns and bandwidths, and their additional cost
is minimal as only one extra process is required in the production of the
- EcoTag technology has been
developed as a seperate technology datapack for other UHF manufacturers
who wish to use its features in their products
- EcoTag technology allows
smaller antenna systems to be developed which operate with good efficiency.
December 2003 saw the launch of a production 250 microwatt version packaged
in an 80mm by 33mm format.
What can we do with half a watt?
To have a transponder system which is going to
be low cost for manufacture, and give ranges of 4 to 6 meters, the chances
are that it will be passive and operate somewhere in the UHF frequency
band, and more specifically in the 400MHz to 930MHz band. Passive indicates
that the tag does not have a battery and receives its energy from an energising
field from the reader. The strength of that field and the RF sensitivity
of the transponder determines the range at which transponders will receive
sufficient power to operate.
When very low cost E-field tags were first developed
in South Africa in 1991, energising field strengths of about 100 watts
(ERP) were needed. Although this sounds a large number it is achieved by
using a cell phone car booster and a simple antenna and is very safe.
US regulations required this to be reduced to
30 watts to fit their spectrum planning (a 4 watt amplifier and a simple
Europe has had a number of different regulations
and as part of unification has allocated a band that can now be used for
RFID but has set the power threshold for the reader at ONLY 0.5 WATTS (ERP)
but information is that this level is soon to be increased. Conventional
passive tags would be lucky to achieve operating distances of 25cms on
such a low power.
EcoTag was borne in South Africa in April
1999 as the result of research by Trolley Scan, the inventors and
developers of Trolleyponder®.
Hoping to increase the operating distance of their transponder system by
a few centimeters, their research has led to measured improvements in the
energy conversion of transponders from the RF energy received at the antenna
to the operating circuit in excess of 200 times . This means that a passive
transponder operating in the UHF band can now be read over a zone 5.4 meters
wide if needed, and all on 0.5 watts ERP!.
- Many EcoTag transponders have been built
to verify repeatability and the technology has been incorporated into the
RFIDmodule version which is supplied as part of the evaluation system.
- The same energy field characteristics and modulation
is used as the earlier technologies, except at lower power.
- The antenna does not use resonant circuits to
achieve the improvement, and bandwidths of EcoTag are limited by
the bandwidths of the antenna system, with the EcoTag improvements
still having a bandwidth of up to 100 MHz so maintaining the frequency
agility characteristics of the tag.
- The preserving of the frequency agile property
of the tag technology with EcoTag allows the same transponder to
be read in different countries on different frequencies. For example in
the US region 902-928MHz can be used for this application, while in Europe
869.4 - 869.65MHz has been allocated. This rules out the use of high Q
resonant circuitry if the intention is to use the tag for international
- Radiation patterns of the transponder antenna
system remain the same as those of the non-EcoTag systems.
- EcoTag is designed for passive transponder systems thereby allowing
very low cost transponders to be produced with good operating range.
- Cost in implimenting the EcoTag improvements
is minimal as only one extra process in producing the transponder is needed.
- Although EcoTag technology was developed
licensees, the technology can be applied to other systems and protocols.
- Trolley Scan are continually testing and measuring
prototypes to validate their theoretical models. !
- Further developments with EcoTag recently have
increased this sensitivity to allow reading zones of 5.4 meters on 0.5
- Trolley Scan have been granted the trademark
EcoTag® to describe this very low power technology.
- Trolley Scan have been granted patents
for EcoTag technology, in many countries including the US and Europe.
- All Trolleyponder
manufacturers have rights to use the patents as part of their technology
package and EcoTag improvements will be incorporated into the single chip
versions being produced by the licensees.
|The above chart compares average cost and operating range of the RFID
technologies currently available. Trolleyponder® and EcoTag® technologies
are UHF operating typically in the 860-930MHz band.
Test results showing
the measured bandwidth of an EcoTag version
covering both the EU and the US
RFID frequency bands.
The above are results on a particular model of EcoTag. In a similar
can be built for other operating frequencies.
|History of power reduction development
in the 900 Mhz band
Mike Marsh has been involved in the development
of Transponder systems in the 900 MHz band since inventing the first low
cost multiple transponder protocols in 1990. Passive transponders extract
their operating power from the energising field radiated from the reader.
During the past twelve years, technological and design developments have
reduced the energising power requirements needed for transponders from
Effective Radiated Powers (Antenna gain times transmitter power) of 160
watts in 1990 to the EcoTag levels of 0.5 watts.
In December 2003, Trolley Scan launched its EcochiptagTM
version, where the EcoTag properies are applied to a simple small antenna
giving good efficiency, small size and simple manufacturing methods.The
sensitivity of the EcochipTag version is as low as 250 microwatts.
The following graph shows the energising requirements
needed in the different periods in order to obtain operating distances
of 4 to 6 meters.
Graph showing the amount of power needed to get 900 MHz band passive
transponders to operate over a 4 to 6 meter range.
A comparison of passive RFID systems
Magnetic coupled technologyies - 125kHz and 13.56 MHz showing typical ranges
achieved with standard sized readers
Electric coupled technologies - All other systems shown based on a 4 watt
ERP energising field and 2.5 volt logic
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