logo    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 range

  1. 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.
  2. 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.
  3. 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 component.
  4. EcoTag technology has been developed as a seperate technology datapack for other UHF manufacturers who wish to use its features in their products
  5. 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 antenna).

      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 trade.
  • 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 for Trolleyponder® 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 watts ERP


  • 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.

Technology comparason

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.
Bandwidth of EcoTag

The above are results on a particular model of EcoTag. In a similar manner EcoTags 
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.

History of power reduction requirements in 900 MHz band

Graph showing the amount of power needed to get 900 MHz band passive transponders to operate over a 4 to 6 meter range.

Technology comparisons
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

Trolleyponder®,EcoTag®,TinTag® and EcochipTag are the trademarks of Trolley Scan (Pty) Ltd

|Home | Trolleyponder developers section (password)| |
Trolley Scan (Pty) Ltd © / info@trolleyscan.com