What is the difference between passive and active RFID technology?

Passive and active refer to how RFID tags function. Passive tags have no internal power source. The tag is not able to communicate until it is energized by the broadcast of an RFID reader. The RF field produced by the reader provides sufficient energy to the IC on the tag that it is able to reflect (passive backscatter) energy to the reader. Because passive tags do not contain batteries or extensive electronics, they are cost effective to mass produce costing as little as 10 cents each. Of course, there is a tradeoff to passive technology. Most RFID readers can only hear a passive tag if it is positioned within 15 feet. In contrast, active tags have a battery which allows them to communicate on a consistent schedule. This stronger broadcast can be heard by RFID receivers up to hundreds or even thousands of feet away. Most active tags will beacon every second or less, so they are easier to locate in real-time. Active tags are more complicated to manufacture and have more parts, so they can cost from $10 to $100 each. ODIN has used both passive and active technologies, so we can guide clients through the tradeoffs between these two approaches and help them identify what will provide the best solution for their needs.

Is RFID secure?

When designed properly an RFID system is more secure than existing data driven systems because the RFID component can add another layer of security. The issue of operational security always comes down to system design. The high-profile MIT fare hack of subway cards using RFID was a perfect example of a poorly designed system €“ all the information and value was put on one layer on the card itself.

An RFID system designed like the license plate databases most motor vehicle departments use can be the most secure system in the world. The RFID only holds a number which is associated with a highly secure database file.

Current versions of RFID silicon provide robust password protection and anti-counterfeit features adding another layer of security on top of a license plate like system.

In addition to having a rewritable portion of memory, the tag ships with a permanently locked unique Tag Identifier (TID), which is hard coded into the silicon and can never be changed. This means that even if an EPC number is replicated, there is no way of duplicating the TID of an original tag. As applications continue to leverage the TID number, RFID solutions will become increasingly more secure. In addition to the TID, up to 608 bits on board the tag can be locked using a password.Although less robust, this feature provides additonal protection against ill intention.

Before installing RFID readers, is it necessary to perform an Ambient Electromagnetic Noise Test?

It is always worthwhile to measure AEN when deploying RFID.  It enables you to understand whether there is interference present, how significant it is and how to mitigate the impact when present.  We recommend conducting a Full Faraday Cycle Analysis (FFCA) where AEN is measured over a 24 hour period and a Mobile Spectral Analysis which can identify the interference locations and sources.  If you do not have access to a spectrum analyzer you can set up your readers and hope for the best, but if you experience read issues you won’t know if it is caused by your design, configuration or interference.  This makes optimizing the system difficult at best.  Read accuracy is essential for RFID systems.  It is a key variable that can eliminate exception processing and lead to 3-5x productivity improvements.  Identifying and eliminating sources of AEN is one of the tolls available to ensure an accurate RFID configuration.

Furthermore, conduction AEN and FFCA tests will reveal any other systems in place that could be negatively impacted by the interference from the RFID installation.  This is especially imp ortant to check in sensitive environments, such as hospitals, where equipment can be highly susceptible to interfering RF.  We have had a few cases in warehouse and retail operations where installed wireless phone systems communicated using the UHF ISM band, the same spectrum as is used for RFID.  Installing an RFID network in these locations could have caused interruptions to the phones.

It is also good to check the tags you plan to use attached to your product to make sure they are appropriate tags.  Depending on your specific needs there may be other tests that will help to ensure that the system operates appropriately and meets your design goals, but AEN and FFCA are certainly good places to start to make sure the system works at a base level, expanded tests will make sure the system works well.

How can I identify the specific location of my assets?

RFID technology offers the ability to track assets by zones on an event basis, or track assets within a few feet on a real-time basis. The decision on which route to follow depends upon the size of the investment and the accuracy/security desired.

Event based systems rely upon a read event, such as passing an asset through a portal or conducting an inventory using handheld readers. This approach uses lower cost passive tags, but does not provide precise location. For example, if a RFID reader is placed at the doorway to a storage room, an event based system will provide knowledge when the asset entered the storage room, but it is not able to say on which shelf the asset was placed.

Real time location systems (RTLS) usually require active tags that beacon and can be triangulated from long distance by several RFID receivers. The higher cost of active tags increases the cost of this technology, but guarantees high security and immediate knowledge with the touch of a button. For example, this technology can show the asset traveling throughout the building and into the storage room, follow the asset as it is placed upon a shelf, and indicate if the asset is moved to another shelf.

New RTLS technology has emerged which is able to function with passive tags, but this technology is in its infancy and is not effective in office environments.

How should the physics of RFID affect my project approach?

The physics of RFID is the key to a successful will make your project a success or failure.  Because RFID tag performance varies as a function of tag type, orientation, range, substrate and the material to which the tag is affixed, many interdependencies exist between the physics of RFID and business process objectives.

An informed project plan accounts for RFID physics through evaluation and testing at key points in the solution design cycle.  In addition to tag testing and site evaluation, detailed use-case design mitigates the risk of deploying a system that does not work perfectly the first time.

Will the use of RFID on vials containing biologics be harmful to the product due to the RF radiation?

Excessive power could indeed damage biologics.  However, the necessary exposure dose to cause damage is very high,  A 2005 study by Robert Seevers, showed that only when a sample was exposed to continuous RFID interrogation for 16 hours similar damages to other more common radiation tests were observed.  For the full report from this study, please see .  And for more information on the use of RFID in hospitals, read this article.

I need to track an object which travels at speed of up to 120Km/h, in an area of 10m X 20m. The object is a ball, so the tag must be small. I need to determine the position of the ball with 40cm precision every 10 msec. Is it possible to do this with Odin products?

We are not aware of an RFID system that can provide you with the accuracy you need. While some Ultra-wideband (UWB) systems can achieve up to 30 cm accuracy in a space that size, the tag size would likely be too large because of the onboard battery and the speed would reduce the system accuracy. Additionally the refresh rate of 10 ms would also not be available in systems as provided today. If you wanted to pursue this further, you would need to embark on custom development or consider an alternative technology such as image processing.

Is it possible to get a read distance of 10 - 15 feet from a passive label?

There are many UHF RFID tags, with read range up to 10 ft to15ft. The passive transponder technology available in the UHF region changes rapidly due to an evolutionary process forced by the chip designers and by new tag antenna designs. Read range basically depends either on the reader sensitivity or on the tag sensitivity. Tags with larger antennas are expected to harvest more energy from the interrogation field leading to greater read range, however interrogators with better receive sensitivity can detect a weak backscattered signal from the tags.

Is there a way to use passive UHF for laptop security? Is inside placement secure for the assets?

In fact, at ODIN technologies’ World Headquarters in Ashburn, Virginia we are currently using passive UHF RFID for IT Asset tracking, including laptops, phones, printers and lab equipment.  RFID tags are commonly used in labels that can have human readable information and or barcodes on the exterior with the RFID tag hidden underneath.  RFID tags can be de-tuned to the point of non functioning by close proximity to metal, however many tag manufacturers make Metal-Mount tags designed for use on metal.  Testing of various tag types and locations can show whether standard tags will suffice in your use case, or if a metal mount tag is required.  Depending on the results of a test, internal mounting may not be necessary, but if it is, it should certainly be a secure option.

What are the limitations of RFID?

A common limitation of RFID technology is memory size, which varies substantially from product to product. Some tags are writable and others are not. Some tags can store only 96 bits of data, while others store 64 MB. Identifying the best technology for your application is critical in the solution design process, since memory size typically affects cost. RFID tag read range can also be an additional limitation. It varies as a function of tag type, what the tag is applied to and reader power output and receive sensitivity. Some passive interrogation systems, for example, are substantially more sensitive than conventional fixed reader technologies and have significantly different value propositions. End users often compare apples to oranges when evaluating the read range of RFID technologies. Active tags, (with an onboard battery), can transmit their ID up to 3000 feet away, while their passive counterparts (which harvest energy from an RF field) often cannot exceed a read range of 15 – 75 feet. Finally, most RFID tags only function over a single air protocol. For example, an EPC C1/G2 compliant tag will not respond to commands compliant with the ISO 18000-6a protocol. If you are designing an open loop system (receiving tagged product from a partner) it is important to account for the variety of tag types you expect to receive when designing your reader infrastructure.

What frequencies are used for RFID?

Radio signals are used by a wide variety of technology, from cell phones to television. To prevent wireless technologies from conflicting with each other, different technologies are assigned to different radio frequency bands. For example, AM stations broadcast around 1 MHz and FM stations broadcast around 100 MHz. RFID has also been assigned several specific bands, but this varies around the world. A few common frequencies include:

  • 13.56 Mhz -> High Frequency (HF) band used worldwide for passive RFID tags such as in keyless entry cards.
  • 433 Mhz -> Ultra-High Frequency (UHF) band used by many active tags.
  • 902 – 928 MHz -> Ultra-High Frequency (UHF) band used by passive EPC Gen 2 RFID readers in the US.
  • 865 – 868 MHz -> Ultra-High Frequency (UHF) band used by European passive EPC Gen 2 RFID readers.
  • 2.4 GHz -> WIFI frequency band used by certain US active tags.

ODIN has experience with RFID technologies across all of these bands, in fact, our lab has been certified by the FCC to allow testing of RFID equipment and tags across the worldwide RFID spectrum. We are focused on addressing end user needs by developing best of breed technology solutions.

What is a metal mount tag?

Standard passive EPC Gen 2 RFID tags will not function when placed on a metallic surface because it detunes the tag antenna. Metal mount tags are created specifically to solve this problem so metal objects can be tagged with RFID.

This objective is achieved through one of three techniques:

1.) separate the antenna from the metallic surface

2.) Tune the tag specifically to operate in close proximity to a conductive plane and

3.) Build a metallic backplane into the tag design.

Metal mount tags generally cost more than standard passive tags because they require additional materials and are produced in smaller quantities, but the plastics supporting the tag also make the tag more durable for long-term use. This type of tag is often used for tracking IT assets such as computers and servers. ODIN has completed extensive tests of metal mount tags to understand the nuances of tag performance and learn which tags are best for specific uses. These findings are available the through the €œMetal Mount Tag Benchmark€ and the €œIT Asset Tracking Benchmark€ found here.

What is a reader? What is a tag?

A passive RFID system is composed of a reader, antenna and tag. Readers and tags utilizing the same air protocol can communicate with one another. Examples of air protocols include the EPC Gen 2 air protocol (passive UHF), ISO 18000-7 (active) and ISO-15693 (passive HF). The interoperability of EPC Gen 2 compliant readers and tags has made passive technology in particular, broadly useful for shipping, retail, and inventory purposes.

A reader includes a transmitter, receiver, and intelligence to manage communication. An antenna connects to the reader and provides an outlet for the reader to broadcast radio frequency (RF) energy as well as receive tag responses. Common readers are restricted to broadcast no more than 1 Watt of energy. A passive tag includes a thin metal inlay that acts as an antenna and a small microchip that includes the logic to respond to communication. The microchip stores information within its memory that it is able to send to the reader if the reader communicates to the tag. In the past, tags have stored up to 96 bits of memory. Today many tag silicon products store 512 bits and more.

What is battery-assisted RFID?

There are three types of RFID tag: Active, Passive, and Battery Assisted Passive (BAP).  Active tags use batteries to power all functions of the tag; both the receiving and transmitting of signal as well as the power for the processing and memory chips.  Passive tags use no battery at all, and rely on drawing the power from the incident RF wave from a reader’s antenna.  Battery Assisted Passive tags utilize a battery for the operation of the internal circuitry to manipulate and return the incident RF energy to a reader.

By using an internal power source, active tags can store and transmit significantly more data over greater distances than a passive tag.  Passive tags, however, are able to be designed very discretely in minute form factors, and cost orders of magnitude less than an active tag.  Battery Assisted Passive tags allow greater read range without increasing overall costs substantially or adding too much bulk to a tag label.

What RFID Frequencies are safe to use in a Healthcare/Hospital/Clinical environment?

All types of RFID have been used safely in hospitals, from active to passive, and Low Frequencies (LF) to High Frequencies (HF) to Ultra High Frequencies (UHF).  It is imperative, however, to conduct a site survey before installing any RF equipment to ensure that there will be no conflicts with any of the existing hospital equipment.  The FDA has not yet published any report on RFID, but there is a set of draft guidelines for the use of wireless medical equipment which can be useful as a baseline for installing an RFID system.  For further reading, please see this article about the safety of RFID in hospitals. what type of tag is the best to be insrted in a bus ticket.and which reader do you portable reader do u advice to read these tickets without disturbig the passengers. In these types of applications HF RFID tags would work best. However cost can be an issue since HF tags are more expensive than UHF tags. UHF systems can reduce the cost, but they cause cross read issues. There are also near field RFID systems, based on UHF, whose potential cost and other benefits may lead them to being used in such applications.

Why do readers not always work?

The RFID network is an interdependent system, when there is a failure it is usually not the cause of one single component. Readers are often blamed for performance issues unrelated to the reader itself. Network connectivity and software uptime have been the cause of nearly 80% of support calls.nHowever, when readers have proven to be the root cause, issues including physical damage, poor power connection, ompetition for the relevant frequency band and memory corruption have been identified as causes. These issues make RFID reader monitoring a critical consideration in overall system performance. Before you deploy any reader in a production environment you should also pre-certify the reader for FCC or ETSI compliance and performance optimization in a reputable RFID lab. This inexpensive step can save hours of troubleshooting on site, and reduce down-time related to business interruption.

Why do RFID tags not always work?

Tags don€™t always work because they may be the wrong design for the job, placed in the wrong location, or masked by some interference. RFID tags are tuned electronic circuits requiring a special match between the tag’s antenna and integrated circuit(IC), called complex conjugate.

Just like your car radio must be tuned to a specific station to hear correctly, and the car€™s antenna needs to be up to get a good signal. If an RFID tag antenna is placed near metal it can be detuned, essentially blocking the signal, this leads to a mismatch with the IC.

The tag system is then unable to harvest energy from an electromagnetic field, causing it to not function. This issue can and has been resolved through testing for the optimal tag for the item to be tracked. For instance specialized technologies designed to work well on metal emerged in 2008 which make tracking items like servers or laptops 100% reliable. But the trade-off between cost and performance is important, since tag costs are often recurring and can constitute a major budget line item.

Who you buy the tags or labels from also can determine why it may not work. Quality control can have a major impact on the number of bad tags per any given amount of tag stock. Some label converters will make tags that guarantee 99.99% €œgood tags€ wear others will offer cheaper price but require the end user to do their own quality control. So bad tags can be the cause of missed reads as much as picking the wrong tag or location.

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