Trolley Scan(Pty) Ltd
RFID Newsletter No 66 |
7 June 2007
Major technical achievement - a small form tag with a long range
Trolley Scan announce the develpment of a slightly larger-than-credit-card sized tag that is compatible with both the RFID reader and the RFID-radar products, and which is 600 times more sensitive than the standard 200uW credit card sized tag that they supply. This additional sensitivity translates into increased operating range with a smaller sized tag.
Trolley Scan have developed a 0,3uW Rf power transponder that is housed in a 90mm by 60 mm by 8mm block of polypropylene plastic and which is covered by a strong rubber covering. The tag is a backscatter transponder that will respond to signals over an 860Mhz to 960MHz bandwidth, giving an operating range of up to 40 meters when illuminated with a 2 watt energising signal.
To achieve this performance was a significant technical challenge that took approximately six months. It is a complex device. When used with Trolley Scan RFID readers it will give its identity over the range from 1 cm to 40 meters, and with the RFID-radar it will give the identity and the exact position.
Information for the technically orientated
Antennas that have a dimension of half wavelength are efficient and RFID is about optimising efficiency. When you shorten antennas to less than half wavelength, the efficiecy drops off dramatically (for example halving the dimensions can lose 97% of the performance).
A second factor is that the antennas are influenced electrically by items that are within the half wavelength zone of the transponder. These items influence the waves arriving at the antenna and usually degrade the performance of the transponder when it is attached to different items such as concrete blocks or metal items.
When designers leave the half wave length dimensions, a property called the impedance of the antenna changes dramatically which influences the transfer of power between the chip and the antenna and hence the efficiency of the transponder system. In some cases these changes can be compensated for in a simple manner, and in other cases the fix is very complex.
The challenge was to develop a transponder that would be very sensitive, would have a form factor similar to a credit card, and would not be strongly influenced by items to which the transponder was attached.
The new transponder is about half the physical size of the already successful Claymore tag used with the RFID-radar, and yet gives nearly the same range performance
RFID Newsletter No 63
Forthcoming development - credit card sized 35 meter range tag.
UHF frequencies, by the laws of nature, allow long operating ranges with practical antenna sizes. Operating range is a function of efficiency of the antennas which means antenna sizes that will have a dimension of about 16 centimeters at these frequencies which is the half wavelength dimension.
Trolley Scan are currently testing a new design for a battery assisted credit card sized tag that will operate at 35 meters.
The new tag is similar to the Claymore tag provided to RFID-radar users in that it contains a fair volume of polypropelene plastic to try to make the transponder more neutral to the influence of being attached to items that they are tagging. Generally items that are in the near field zone of a transponder will influence the performance of the radio waves in the vicinity of the tag and the challenge is to neutralise these effects, while keeping very low operating energy requirements and small size.
These tags are not active tags in the sense that they do not transmit any signal from the tag. They reflect some of the energy arriving from the energiser of the reader back to the reader at the same frequency. This means that the tags will respond to multiple readers simultaneously and correctly if the readers are operating on slightly different frequencies and are in close proximity to each other.
This frequency agility property allows many reader systems to monitor correctly the same zone with overlapping fields, and it allows for goods to be tagged in one country and read correctly in another country at a very different operating frequency.
These tags are still being tested, and will not be supplied with current systems till all hurdles are sorted out. They will be compatible with all existing RFID readers and RFID-radars supplied by Trolley Scan.
Because Trolley Scan products have a wide range of packaging options and operating sensitivities, they are found in a wide range of applications by users in 49 countries. They operate at long ranges; large numbers of transponders are allowed in a zone; are very fast to respond and allow maximum speeds up to 300kph; and the readers are simple to interface to software. The same transponders will operate with Trolleyponder RFID reader systems if just identification is needed,or with the RFID-radar system if real time locating is needed.
Users of the technology typically are farmers managing a herd, a vehicle garage managing access for regular clients, a company managing the movement of its laptop computers, a library managing its books and lenders, access control systems for staff, a trucking company monitoring usage of its vehicles, a car hire company checking to see the tyres supplied on its vehicles have correctly been returned, an industrial laundry managing the washing of gowns and overalls for a factory, or even a logistics company managing parcels passing through its warehouse.
TROLLEYPONDER/ECOTAG RFID Newsletter No 59
24 August 2006
Ruggedised version of laundry tag developed
The tags can be read in single situations or when packed in boxes for shipping. They are attached to uniforms that are repeatedly returned to the laundry for cleaning and have passed through the process already hundreds of times.
Due to the narrow band low interference technology of the RFID reader system from Trolley Scan, multiple readers are able to operate in the laundry continuously monitoring the progress through the plant.
Bushmantech have developed a software system that processes data from the readers to track the individual items through the process, and to monitor their usage and garment life.
Autoscanning Systems and Bushmantech will be expanding this system to other industrial laundries.
TROLLEYPONDER/ECOTAG RFID Newsletter No 58
1 July 2006
Low weight transponders for animal tracking
Trolley Scan provide a range of transponders, from 200uW credit card sized Ecochiptags, Ecowoodtags, Ecosportags, and laundry tags to stick tags and top of the range Claymore tags. The sensitivity of these tags varies from 1000uWs to 0.3uWatts depending on construction and sophistication. The Claymore tags use a large block of plastic (118cu cms) to focus the energy onto the sensor and give a tag that is independent of influence from the goods to which they are attached. Depending on which tag one chooses, one gets different operating ranges from the low power energy of the Reader.
All these transponders operate in a mode where they reflect received energy from the reader back to the reader. This means that the tags themselves do not radiate any energy, and that they will respond in situations where they are in overlapping coverage zones to many readers/radars simultaneously, with the correct information allowing them to be positioned and identified without being influenced by more than one reader/radar covering a zone. They also will respond to radars/readers over the whole 100MHz UHF RFID spectrum needed for international compatibility.
The radar has stimulated interest from a University project where they would like to locate accurately the current location of small mammals. Here we need long range, but a small light weight transponder. Unfortunately the antenna length is set by the operating frequency which means the need for a thin wire antenna but the transponder needs to be small and yet lightweight so as not to overload the mammal. Trolley Scan have developed a very small transponder that can be used in this application and yet is very lightweight, having just three small chips on the transponder to provide all communication features over long ranges.
TROLLEYPONDER/ECOTAG RFID Newsletter No 55
17 April 2006
The transponder has to collect energy from the energising field of the reader and reflect some of that energy back to the reader. Generally the transponder's radiation pattern is uniform in all directions around its axis.
When a tag is attached to a major object - like a railway container - then no energy can pass through the object, meaning that one does not need the transponder radiation pattern to be uniform around the axis as half of it is screened by the container.
Trolley Scan have developed a new series of transponders called Claymore Tags. These are directional transponders, made to be attached to large objects and where they will always be read from one side. They comprise a specially designed plastic block with appropriate air spaces, which acts in a similar manner to that of a lens for an optical system, focussing the incoming radio energy onto the transponder, and then directing the reflected energy back towards the reader.
The use of this design means that much greater transponder sensitivities can be achieved with much greater ranges, and the transponder's performance will be the same no matter to which item it is attached.
TROLLEYPONDER/ECOTAG RFID Newsletter No 53
10 February 2006
Gee! was it cold in Europe this winter!
Despite this our equipment works in very cold temperatures.
In January this year, we had an urgent call from a client in Europe who had installed a major automated parking garage system for more than 1000 cars last year. He was finding in the exceptionally cold winter days, when the temperature got to minus 25 deg C, that cars arriving at the garage were being read accurately, but for cars that had been parked a long time and just started, reading of transponders was starting to become intermittent.
Investigations showed that the oscillator in the transponder was slowing down in the very cold temperatures, and was getting beyond the capturing range of the digital signal processing algorithms that are used in the receiver to detect very weak signals coming from very low power transponders at a long distance. This became a problem once the temperature of the transponder dropped below -20 deg C, a temperature never experienced in Africa.
Trolley Scan quickly developed a fix for the digital signal processor which can be loaded in situ by the users to extend the temperature range to minus 40 degrees Centigrade. This software can be requested by owners of our RFID readers if they are experiencing any unreliabilities in very cold temperature.
TROLLEYPONDER/ECOTAG RFID Newsletter No 52
20 January 2006
Trolley Scan develop a 30 meter range tag
How much range does one need for an RFID system?
Trolley Scan have in the past supplied their 200uW Ecochiptag with a 13 meter operating range. The key distance for RFID readers seem to be about 6 meters as since the RFID energy penetrates walls and floors you do not want to read the contents of the adjacent room when scanning assets; a ceiling mounted reader can read all goods passing through the doorway/passageway; and goods that you are reading are directly in front of the reader. As we have increased the range with technology inprovements, so we have reduced the energising power (down to between 0.5 and 3 watts) and we have widened the coverage field of the antennas.
The arrival of the RFID-radar, with its ability to measure range and location change the requirements and pushes developments in low power transponder technology. There seems to be interest in having working ranges as far as 100 meters for each radar as the goods are located by their position data rather than just knowing the goods are somewhere inside the field of coverage.
Trolley Scan announce the development of a 5 microwatt transponder that is compatible with its readers and the RFID-radar. With an improved antenna system this tag has been measured at a distance of 49 meters from the reader. With conventional antennas, it operates at 25 to 30 meter range. The tag is compatible with all the other tags and both portable and fixed readers provided by Trolley Scan. It can also be used with the RFID-radar. The tag is frequency agile, and will operate at all frequencies between 860Mhz and 960Mhz, needing just 5uW of RF power in its 134 to 149 sq cm aperture. The tag is a backscatter tag, using just 10 kilohertz of bandwidth, is a tag talks first protocol - generating no interference, and operating with the Trolleyponder(RIST) protocol.
In order to get this superior performance,this tag is no longer a single chip solution meaning that it is at a higher cost that the standard 200uW credit card versions.
As this range is so large we do not see this as a standard item for normal RFID readers wanted by most users. Hence the tag is listed in the new pricelist and can be ordered as an additional item from Trolley Scan with small systems. A data sheet is available at
TROLLEYPONDER/ECOTAG RFID Newsletter No 48
18 August 2005
Testing a 2 microwatt transponder
Some applications need a transponder to be read at distances of 100 meters from the passive reader. To achieve this Trolley Scan have started testing a 2 microwatt (2uW) version which is already operating at distances of more than 30 meters and should achieve distances as far as 130 meters depending on the sensitivity of the receiver in the reader. These transponders are special purpose versions and will be more expensive than the standard Ecotags when available.
RFID Newsletter No 37
Another technical breakthrough - production versions now need only 200uW
Improving transponder sensitivity is like improving fuel consumption for a car - you can never have enough!!!. Every time the sensitivity improves, it means that the transmitted power of the reader can be reduced, or the operating range of the transponder system increases.
The new transponder can be read 8 meters from a reader radiating just 300 milliwatts of power, similar to that radiated from a cell phone. In addition, due to the miniscual amount of power needed to operate the transponder, polarisation becomes less important and transponders can be read on almost any polarisation even with linear polarised antennas. The 8 meter range is achievable even if the transponder is attached to metal.
In 1994 a state of the art transponder used in the original Supertag version developed by a team led by Mike Marsh, and shown to the world with a trolley(cart) of 38 items being scanned at the Pick n Pay hypermarket in Pretoria South Africa, needed 6000uW of RF power to operate. In 2001 Trolley Scan started delivering 1000uW versions with its evaluation systems. In December 2003, Trolley Scan delivered 350uW credit card sized versions, a major technical achievement as the previous systems all needed 160mm dipoles while the credit card sized version was only 80mm long - a size that is inherently inefficient at this operating frequency. Now the norm with the latest developments is 200uW in a credit card sized version.
Comparing the performance to the original Supertag tests, the transmitter power needed now is only 3% of that needed for the original system, meaning smaller transmitters, longer battery life and portable readers. The operating range at the original power used for Supertag is 550% of the ranges then achieved.
Despite the benefits of long operating range and low transmitter power, the Trolley Scan has maintained all its important benefits such as wide operating bandwidth (50MHz for EU/GSM/US compatibility), up to 500 multiple transponders in the reading field, 3D scanning small antenna size and easy to produce.
Users wanting to purchase systems fitted with the new technology can order systems on the http://trolleyscan.com/isosys.html page.
Companies wanting to produce this technology in volume under licence for their applications should contact Trolley Scan. mailto:firstname.lastname@example.org?subject=Want_to_produce_200uW_RFID_systems
Research project - developing transponders for attachment to timber.
These developments are as a a result of the patented EcoTag technology developed by Trolley Scan which enables it to develop specialised systems for specialised situations, without losing overal system performance.
The new product will be developed under the Ecowoodtag trademark.
TROLLEYPONDER/ECOTAG RFID Newsletter No 36
2 February 2004
Transponders on metal at 11 meters!!!
Trolley Scan can answer that with the correct mounting of their EcochipTag, you can get 11 meters with just 1 watt of transmitted power!!
The secret is to attach the transponders correctly to the object. A research report on the matter is supplied with the systems sold by Trolley Scan.
TROLLEYPONDER/ECOTAG RFID Newsletter No 33
9 October 2003
Attaching transponders to metal, wood, paper and athletes
This antenna system has to be super efficient to give good operating range using the weak reader fields typically allowed. Trolley Scan, as leaders in low power technology, have been supplying for a few years EcoTag(R) transponders that need just 1 milliwatt of RF power in free space.
When a transponder is attached to a large object which has different properties from free space, such as an ingot of metal, block of wood, stack of paper or an athlete in a marathon race, the field in the vicinity of the transponder is disturbed and range performace decreases.
As leaders in researching and developing low power transponder systems, Trolley Scan have developed leading edge equipment for measuring the sensitivity of transponders in different situations. A recent research project looking at different methods of mounting the transponders on these bodies has recently been completed.
Among the results that have come from this project, are guidelines for attaching transponders to these type of objects. In the case of a metal ingot, with the correct mounting the sensitivity of the transponder can increase by 300% over that of the free space situation; that is the 1 milliwatt transponder displays the characteristics of a 333microwatt transponder, giving 170% operating range compared to that of free space.!!!
Copies of the report are included in the handbook for the evaluation system, in the datapack supplied to manufacturers, or are available from Trolley Scan.
Transponders for monitoring tampering of packages
TROLLEYPONDER/ECOTAG RFID Newsletter No 25
15 September 2002
34% further reduction in operating power - NOW 12 meter range from passive
Trolley Scan announce that during the past week, ongoing technological developments have resulted in the RF power collected in the transponder's aperture needed to operate a UHF transponder using EcoTag technology, dropping to just 180 micro watts(180uW). This should be compared to the 55 milliwatts needed for a conventional transponder; a three hundred fold reduction in the operating power(zero comma three percent). This development increased the operating range for the development version from 9 meters to 12 meters.
Transponders based on EcoTag technology now need a reader that is 300 times lower powered, or operates over a 17 times range increase - compared to transponders using conventional technology.
Developments by Trolley Scan are incorporated into the manufacturing licencees' products providing the users with the benefits from this very low power technology. This technoloy can be packaged into a transponder that has the frequency agility to operate over the full 860 to 930MHz frequency bands for EU/US operations, and in a footprint small enough to be contained in an ISOcard format.
Trolley Scan license the technology to companies wishing to become large volume suppliers of UHF transponder systems, assisting them start production. Trolley Scan also have a "retail initiative" program for retailers needing huge volumes of transponders at low cost.
TROLLEYPONDER/ECOTAG RFID Newsletter No 22
23 February 2002
Technical breakthrough - UHF in credit card sized antennas
Trolley Scan have been world leaders in the past in developing extremely
low power RFID technology for very low cost RFID transponder systems, primarily
through their patented EcoTag(r) technology.
The reasoning for using RFsensitivity is
RFreader power is proportional to RF sensitivity/(Range*ramge)
Therefore improving the RFsensitivity by a factor of say 10 means the range of the system will be 3.15 times more OR the reader power can be reduced by a factor of 10 meaning smaller readers and longer battery life.
As as benchmark a 5volt logic circuit attached to dipole antenna on a transponder would need 55 milliwatts to be collected in its antenna aperture to operate.
In the past we have reported on our 0.27mW dipole version that we have been able to read over 9.5 meters.
A perceived disadvantage of UHF RFID by some potential users has been the length of the antenna. Typically the length is 160mm at 915MHz (slightly longer for 869MHz for the EU) but this is needed in order to get high efficiency.
Taking a 160 mm long dipole and cutting off 40mm from each end would throw away 94% of the efficiency of the system, that is the standard benchmark transponder would need 726mW to operate - obviously not a practical solution.
The wonders of EcoTag technology now come to the rescue for Trolley Scan licensees.
Using EcoTag patented technology, Trolley Scan have developed a simply designed 80 mm long antenna system THAT OPERATES ON AN AMAZING 0.4mW (comma four milliwatt) RF sensitivity, a 1815 times power improvement compared to the shortened dipole, or 137 times improvement even compared to the full length dipole.
The design allows the entire transponder to be packaged in an 80 by 27mm area, and particularly into the standard ISOcard formats that are requested by users particularly for access control cards or smart labels. (Credit card sized)
The new antenna design means that it is quite practical to read an ISOcard sized transponder at 9 meters.
The design of the transponder is very simple, being two strips of foil and a single chip leading to low cost, small and very low power transponders that can simply be produced in very high volume.
It impacts the future of 13.56MHz technology as with the same size advantages as the older technology, UHF transponders can offer 20 times range advantage while being simpler and cheaper to manufacture than the older technology.
These developments are available to Trolley Scan licensees. Users can expect them to be available commercially by the middle of this year in UHF RFID transponders produced by Trolley Scan licensees.
(PS Despite offering 9 meter range the sensitivity is so low that the new EcoTag ISOcard transponder operates 1000 times below the power levels recommended in the RF health guidelines).
An image of the physical size of the new transponder is available at
TROLLEYPONDER/ECOTAG RFID Newsletter No 20
26 November 2001
Credit card sized antennas for UHF RFID!
The patented EcoTag technology from Trolley Scan gives the manufacturers some additional degrees of freedom.
Trolley Scan have developed an 80mm by 27mm antenna that operates at nearly 90% efficiency!! - an important breakthough in that suddenly credit card sized antennas for UHF RFID are practical.
TROLLEYPONDER/ECOTAG RFID Newsletter No 19
1 October 2001
Transponder sensitivity - a new way to specify UHF transponders?
The physics of radio frequency propogation mean that energy from a reader to power the transponder can more easily be delivered at these frequencies, bearing in mind the compromise of antenna sizes, than at other frequencies.
Below 100 Mhz the mode of propagation is magnetic coupling and range becomes an issue as it is difficult to project the energising field meters from the reader coils.
When the mode of propogation is electric field coupling, the projection of the energising field is no longer an issue as range relates to transmitter power. However, the collecting area of the transponder (called the transponder antenna aperture) where the energy from the reader is intercepted relates to the operating frequency squared, meaning that a 2.45GHz system would need 7 times more transmitter power than a 900MHz system for the same range, while still having an antenna system that is 36% of the size of the 900Mhz version.
The EAN/UCC are lobbying for a frequency in the 860-930 MHz band, the motor manufacturers who require all tyres to now be labelled are specifying this band, and whereas a few years ago there were very few manufacturers providing transponders at this frequency more and more of the established players are announcing that they have UHF transponder systems under development.
A further contributing issue for the frequency band is that the transponders can be so simple, just one chip and a foil antenna strip, that the manufactured costs can become so low that mass acceptance of RFID becomes a reality.
The staff of Trolley Scan have been leaders in the field of UHF transponders since 1990 and now Trolley Scan has taken the developments in this frequency band one step further, namely in the issue of transponder sensitivity.
Passive transponders, that is transponders that have no onboard battery but receive their operating energy from the reader's energising field, collect their energy from the reader, in an area called the transponder antenna aperture and convert it to operating power. In the case of a 915MHz transponder using a dipole antenna, this is an area of 134 sq cms. Trolley Scan have developed a simple form of comparing developments by specifying how much RF energy needs to be collected in the aperture to operate the transponder- called the transponder sensitivity.
RF passive transponder systems are very cruel to electronic designers as although developments in electronic circuitry mean that operating voltages and currents are becoming very low, the reality of transponder design means that only two parameters are really dominant, namely the impedance of the antenna and the operating voltage of the transponder circuit. Even if developments of technology in future meant that the electronic circuits operating current dropped a further 3 fold for example, it would have no impact on the sensitivity of the transponder - a 3 volt logic circuit would still need 23 milliwatts of power to be collected in its aperture.
A 3 volt circuit using schottky diodes in a voltage doubler configuration would need 3.6 volts across the diodes, 1.8 volts RF before the doubler, 1.27 volts RMS RF across the antenna and with a 72 ohm dipole antenna, 23mW RF power. (Even a 0 volt logic circuit - if such a thing was possible - would need 0.6mW to operate!!!)
Trolley Scan in its EcoTag technology is now delivering 1 milliwatt transponders and a 100uW version of the RFIDmodule is on the horizon. This means that the reader's power can currently be reduced by 23 times compared to the 3 volt circuit for the same performance, and 230 times for the future versions. Hence readers become smaller and instead of running down a car battery in minutes, a cell phone battery in an EcoTag reader can last for hours.
Transponder sensitivity can become a simple parameter to allow users to compare different UHF RFID systems in the future for implications on range and reader requirements.
TROLLEYPONDER/ECOTAG RFID Newsletter No 16
10 April 2001
Trolley Scan develop module version of Trolleyponder/EcoTag
In the past a transponder from discrete parts was capable of demonstrating most of the functionality of the technology, except RF and range issues due to the much higher power consumption of discrete parts.
Trolley Scan have in the past month developed a module version which has SIMILAR PERFORMANCE TO THAT OF THE SINGLE CHIP VERSIONS, but which makes use of a number of commercially available over the counter parts. Incorporated into the module are the EcoTag technology features which mean that the module operates on less than 1 MILLIWATT RF energy, (remarkably low power considering theoretical requirements about four years ago showed more than 50 milliwatts would be needed). The module also includes Trolleyponder's 3D scanning features and it is possible to add EAS memory although that is not included in the initial versions.
This module is an important addition to the Trolley Scan portfolio of parts as although the new module costs much more than the single chip versions, it enables users to evaluate the technology in depth and possibly even use the module as a solution for higher value applications as it is possibly cheaper than competitive RFID products,offering much greater range performance at much lower powers.
Trolley Scan have a further 0.27milliwatt version under development and regularly demonstrate it being read over more than 9 meter ranges with less than 1 watt of transmitter power, just more than what is available from a cell phone. The power used by these transponders is so low than more than one hundred thousand transponders use less power than that needed by one 100 watt light globe.
Although in the past these performance issues had been theoretical, the availability of the new module allows users to actually experience long range RFID technology and use them in selected applications.
The module can be produced in standard PC assembly plants and can be supplied by Trolley Scan or some of its partners, or can be assembled by the users themselves for high volume applications from a kit of parts supplied by Trolley Scan.
TROLLEYPONDER/ECOTAG RFID Newsletter No 14
11 September 2000
Single chip UHF transponder
TROLLEYPONDER/ECOTAG RFID Newsletter No 13
22 May 2000 From vision to reality - first single chip delivered
Easter Friday (21 April 2000) will go down in history as the day that single chip low cost Trolleyponder technology became reality!
Trolley Scan, the inventors of the Trolleyponder protocol, were on that day informed by our US partners, that they had JUST RECEIVED and INITIALLY TESTED the FIRST SINGLE CHIP IMPLIMENTATIONS OF THE TROLLEYPONDER UHF RFID transponder.
Trolleyponder technology is likely to revolutionise the features expected from RFID systems in the future. It promises to smash all price barriers due to its unique design and low cost potential.
Designed with the end goal of being used as a barcode replacement technology not only in Supermarket trolleys/karts, but also being ideal for less cost sensitive applications, it includes features of long reading range, 3D scanning, inbuilt EAS, multiple tags, very low power (EcoTag versions) and very low manufacturing costs.
The low cost is achieved by implimenting the entire electronic circuit on a single chip which is attached to a simple antenna.
To date many sceptics have claimed that combining the RF characteristics of the UHF diodes with the memory requirements of a data device, and the low power logic requirements for implimenting a protocol on a single chip have made the concept of low cost RFID a pipe dream - well Easter Friday will go down as THE DAY REALITY DAWNED!!
TROLLEYPONDER/ECOTAG RFID Newsletter No 12
7 March 2000
Trolleyponder technology developments - electrically short antennas
The choice of operating frequency for UHF tags impacts the range and the amount of space needed for the transponder antenna. The power requirements to maintain the same operating range increase with the square of the increasing frequency; while the length of a simple dipole transponder antenna will reduce as the inverse of the frequency.
For example a dipole for a 868/915Mhz transponder would be 16 cms long, while the antenna for a 2.45GHz transponder would be 6 cms long - but the 2.45GHz system would need seven times the power needed for the 915MHz system for the same operating range.
If the dipole antenna is shortened (referred to as an electrically short antenna) to reduce the required space, its efficiency drops off very quickly. A 20% reduction in length results in a 60% loss in efficiency, and a 50% reduction in length result in a 95% loss in efficiency.
Trolley Scan have started a research project to address this problem of reducing the antenna size while maintaining the operating frequency. The developments are being integrated with the EcoTag developments to try to maintain the almost 40 to 65 fold improvement resulting from that technology.
Already we have achieved good results from a 32% length reduction with almost no loss of performance. Our immediate goal is to achieve an 8cm (50%) electrically short antenna for use with 868/915Mhz UHF transponders.
TROLLEYPONDER/ECOTAG RFID Newsletter No 10
7 November 1999
Article on transponder design
At the end of the day the user buys a transponder that comprises a single integrated circuit attached to a simple antenna. What is in the chip and why is it there? Why are patents important in the development of this technology? Trolley Scan have added to their site an article showing the different functionality that is available when designing transponder systems and where EcoTag fits into the Trolleyponder picture. This is specifically written for those who do not have a background in RFID design.
It can be found at
TROLLEYPONDER/ECOTAG RFID Newsletter No 9
12 September 1999
EcoTag reduces power to 1/300th of historical need
Information has been added to the EcoTag page in the form of a graph showing how the required energising power in the 900Mhz band has reduced with time while maintaining comparable operating ranges
Information on EcoTag power developments can be found at: