Advances in passive UHF RFID technology
Apr 21, 2004 Comments (0)
Said Mike Marsh, MD of Trolley Scan-"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 further reduced needing smaller transmitters to do the same job with longer battery life, -, or the operating range of the transponder system increases. The new production transponders can be read 8 meters from a reader radiating just 300 milliwatts of power, similar to the power 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 orientation 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 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.
Trolley Scan provide RFID systems to users in 32 countries.