125 kHz (LF) info 

Low Frequency (LF) RFID is typically defined by radio frequency transponder devices operating in the frequency range of 100 kHz to 140 kHz. Typical frequencies are 125 kHz and 134 kHz. TI-RFID LF products operate at 134 kHz. Other brands operate at 125 kHz.

LF is less susceptible to the effects of nearby metals and liquids as compared to devices operating at higher frequencies (i.e. HF-13.56 mHz, UHF-900 mHz). It is for this reason that the U.S. Fisheries Department uses LF RFID to track fish in streams and major car retailers use LF to inventory automobiles. LF has been available for the past 20 years and continues to be the favorite RFID solution for many applications. Contrary to popular belief, LF has not been replaced by higher frequencies and may never become obsolete due to its robust properties.

Advantages of LF are that it is widely used and has been used for many years, it typically has a longer read range than HF, and transponders can be more compact in certain cases (i.e. glass transponders).

The disadvantages of LF are the fact that only usually one transponder can be read at a time (only one transponder can be in the reading field at a time), the transponders are generally more expensive and typically bulkier than HF tags, and the memory capacity of LF transponders is generally lower than HF tags.

13,56 MHz (HF) info

The High Frequency RFID devices available today typically operate at 13.56 MHz. The original devices developed as HF RFID came from Philips Semiconductor and Tag-it from Texas Instruments. Although these devices all operated on a center frequency of 13.56 MHz their air interface protocols and data structures were totally incompatible with each other.

In 1999 and 2000, Philips and TI agreed to share some of their intellectual property and create the ISO 15693 “Vicinity” card standard and the ISO 14443 “Proximity” card standard. These ISO “specs” currently define the HF RFID smart card and smart label components.

HF RFID devices work on magnetic wave coupling principles, similar to that of primary-secondary windings in transformers, not as conventional radio wave theory, as we know it. HF RFID Readers are matched to loop antennas that convert time-varying electrical current into the magnetic radiation field pattern. Nearby HF tags that are in the field get a current induced in their winding and it is this induced current that provides power for the passive chip to operate.

High Frequency RFID devices have anti-collision intelligence that allows hundreds of tags to operate concurrently in the same antenna field.

Please call us to help you selecting the proper devices for your application.

868 MHz (UHF) EU info

The Ultra High Frequency, UHF RFID passive devices that are available today typically operate in the band of 860 – 960 MHz. The United States has specified 915 MHz while the European Union has specified 868 MHz for UHF RFID applications.

When you review documents describing Low Frequency RFID operating at 125 – 134.2 kHz and High Frequency RFID operating at 13.56 MHz an explaination is given that these technologies use magnetic inductive coupling, similar to transformer action, to provide the air interface between tag and reader. The important point here is the magnetic coupling is NOT radio technology, as we know it. LF and HF RFID are not “radio” devices at all. They are magnetic devices. Magnetic energy fields are very predictable and can provide a very stable and reliable automatic data collection platform.

The wavelength of LF is over a mile long. The wavelength of HF is 66 feet. Both of these distances are far greater than the usable operating range of the tags that probably range from 6 feet to 2 inches depending on reader and tag selected. LF and HF devices work in the “NEAR FIELD”, which is an energy “STORAGE” field. It is primarily comprised of a magnetic component and acts as a very stable storage field for energy.

Now passive Ultra-High Frequency, UHF RFID devices have a wavelength of 12 inches and supposedly can have a working range of 20 feet (in your dreams). The range of the tag is many wavelengths from the reader's antenna. These devices work in the “FAR FIELD”, which is a “DISPLACEMENT” field, comprised of electro-magnetic waves propagating through space, just like “radio” as we have come to know it.

UHF radio waves bounce off walls, shelves, almost everything and cause cancellations in the field energy pattern. This gives us the “can you hear me now” phenomenon. Move 6 inches this way or that and the reception may get better or worse.

This is the technology that Wal-Mart would like on every razor blade pack. Currently Easylogic is working with the major RFID manufacturers to find UHF RFID components that are reliable. Until that time we will continue to recommend LF and HF devices for our customer’s applications. The 3 largest manufacturers of RFID devices in this world today, Texas Instruments Inc., Philips Semiconductors and TAGSYS, have issued a whitepaper describing in detail a comparison of HF and UHF RFID technology characteristics. You can find this paper on our webpage HF and UHF comparison.

Please call us to guide you through the selection process when implementing an RFID solution.