FAQ Answers - About RFID
A. Radio Frequency Identification (RFID) is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to uniquely identify an object, animal, or person. An object (typically referred to as an RFID tag) is applied to or incorporated into a product, animal, or person for the purpose of identification and tracking. The advantage of RFID is that it does not require direct contact or line-of-sight scanning. An RFID system consists of three components: an antenna and transceiver (often combined into one reader) and a transponder (the tag). The antenna uses radio frequency waves or magnetic (inductive) energy to transmit a signal that activates the transponder. When activated, the tag transmits data back to the antenna. The data is used to notify a computer that an action should occur. The action could be as simple as raising an access gate or as complicated as interfacing with a database to carry out a monetary transaction.
Q. What are passive RFID and active RFID?
A. Passive RFID is where the RFID tag’s power is derived from the Reader’s electromagnetic or inductive field. The RFID tag has no battery and is typically low-cost, robust and can last “forever”. The tag stores energy from the Reader’s electromagnetic/inductive field and passes information back to the Reader by modulating the Reader’s own radiated energy.
Three frequency groups are commonly used: LF (Low Frequency), HF (High Frquency) and UHF (Ultra High Frequency) (LF = 125/134KHz, HF = 13.56MHz, UHF 850-950MHz). LF and HF systems typically use magnetic or inductive energy so the operating range is low and usually less than 1 metre. UHF systems use radiated electromagnetic (RF) energy and reflected modulation similar to “Radar”. UHF RFID systems can have ranges up to 10 metres.
LF, HF and UHF passive tags are low-cost, simple devices. Short range LF and HF Readers (range 10cm) can be low-cost also. Longer range UHF Readers (up to 10m) are more complex systems and are relatively expensive.
Active RFID is where the RFID tag has its own power source (typically a small battery). The tag is actually a transceiver and responds to received commands from the Reader and “actively” transmits data back. Active tags can use any ISM or licensed frequency band, the most common being 850-950MHz and 2.4GHz. The range is dependent on both the tag and Reader transmitter power and receiver sensitivity. Active tags typically spend long periods “asleep” to prolong batttery life. Range can be 10’s of metres to several kilometres.
Active tags can be relatively large and have a finite life (batteries need to be changed) and are significantly more expensive than passive tags. Active Tag Readers use a similar level of technology to the tags and can be relatively inexpensive. Some tags can use “passive” circuitry to "wake up" and then “actively” transmit data, this technique offers longer battery life.
See the summary table to compare the differences.
Q. What is the maximum reading range for passive RFID?
A. For LF (125/134kHz) or HF (13.56MHz) passive RFID systems, the reading range is dependent on the Reader antenna size and the tag antenna size. LF and HF RFID systems use magnetic or inductive energy and typically small tags will give small range.
For a proximity LF Reader (like RWD-QT for Hitag, EM4102, etc), maximum reading range will be about 15cm using 7cm diameter Reader antenna and credit card sized tag. For a proximity HF Reader (like RWD-MICODE for Mifare, ICODE), maximum reading range will be about 5-7cm for Mifare and 10cm for ICODE using 7cm diameter Reader antenna and credit card sized tag.
For UHF (850-960MHz) passive RFID systems, the reading range is dependent of the Readers transmitting power and receiver sensitivity and the physical environment. Low-frequencies penetrate materials and liquids better. Higher frequencies (particularly UHF) can be absorbed and blocked by liquids and reflected by hard materials.
Q. What are the main RFID standards?
A. Many RFID technologies are proprietary and use patented technology and protocols defined many years ago when RFID was first used for simple applications such as access control. More recently ISO standards have been defined for different frequencies and transponder technology. These ISO standards can define the modulation techniques and communication protocols but often the memory size, security features (encryption etc) are still proprietary to one manufacturer or another.
Examples of RFID standards are:
- ISO11784/785, 134kHz “animal tags”
- ISO14443A, 13.56MHz Mifare cards/tags
- ISO15693, 13.56MHz ICODE cards/tags
- ISO18000-6B/6C, 850-950MHz UHF Gen1/2 EPC cards/tags
Many popular passive tag types are widely used and regarded as “standards” but are actually proprietary technology from one company or another. In many cases the technology has been licensed to other manufacturers to allow even wider use.
Examples of popular RFID card/tags types are Hitag, EM4102, MIFARE, and ICODE. See the summary table to compare the differences.
Q. Does IB Technology support these main standards?
A. Yes, we support the most popular “standard” and “proprietary” RFID card/tag technology including: Hitag1, Hitag2, HitagS, EM4102, Mifare1k, Mifare4k, Ultralight, Mifare ProX, Smart-MX (DESFire) and ICODE
Q. Is it possible to have a ‘passive’ system with a range of several metres?
A. No. “Passive” RFID systems, LF (125 kHz) and HF (13.56MHz), systems use Inductive (magnetic) coupling technology and are not capable of achieving the ranges beyond a few centimetres. The only practical solution is UHF (EU 860MHz, US 915MHz, EPC Gen1/2 types) “passive” tags and a UHF long-range Reader. UHF tags use an RF back-scatter approach (similar to Radar) rather than Inductive coupling and can handle up to 10 metre range and multi-tag operation. The downside to long-range “passive” UHF is that RF signals can be blocked and attenuated by water (and other absorbent materials) and can be reflected off hard or metallic surfaces. Readers can also be expensive (around GBP 500+ for a 5-metre read/write system with integrated antenna).