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Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to automatically identify people or objects. There are several methods of identification, but the most common is to store a serial number that identifies a person or object, and perhaps other information, on a microchip that is attached to an antenna (the chip and the antenna together are called an RFID transponder or an RFID tag). The antenna enables the chip to transmit the identification information to a reader. The reader converts the radio waves from the RFID tag into digital information that can then be passed on to computers that can make use of it.
An RFID system consists of a tag made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from the field created by the reader and uses it to power the microchip's circuits. The chip then modulates the waves that the tag reflects back to the reader, which converts the new waves into digital data.
RFID-enabled systems help companies cut costs, improve customer service, reduce labor, increase accuracy, and improve production throughput. The technology is superior compared to the limitations of traditional ADC technologies such as barcode technology. Barcode and visual systems rely on a clear line-of-sight and require a relatively clean and moisture-free environment. Touch memory does not use optics but is very short range and requires a relatively clean environment because contact must be made to read the tag. Radio waves, on the other hand, can go through and around objects to read the tag at comparatively large distances.
RFID has at least two strong advantages; it can be read without being seen, meaning it can be hidden for aesthetic or other reasons, and many tags can be read virtually simultaneously, differing dramatically from bar codes which must first be located, then read one at a time. Reading 20 barcodes could easily take 15 to 20 seconds or more, while reading 20 RFID tags under the same circumstances is being done today by adopters of RFID in less than two seconds.
| RFID | Barcode | |
|---|---|---|
| Line of Site | Not required (in most cases) | Required |
| Required Signal Strength |
Passive UHF RFID:
| Several inches up to several feet |
| Read Rate | 10's, 100's or 1000's simultaneously | Only one at a time |
| Identification | Can uniquely identify each item/asset tagged. | Most barcodes only identify the type of item (UPC Code) but not uniquely. |
| Read/Write | Many RFID tags are Read/Write | Read only |
| Technology | RF (Radio Frequency) | Optical (Laser) |
| Interference | Some RFID frequencies don't like Metal and Liquids. They can interfere with some RF Frequencies. | Obstructed barcodes cannot be read (dirt covering barcode, torn barcode, etc.) |
| Automation | Most "fixed" readers don't require human involement to collect data (automated) | Most barcode scanners require a human to operate (labor intensive) |
Just as your radio tunes in to different frequencies to hear different channels, RFID tags and readers have to be tuned to the same frequency to communicate. RFID systems use many different frequencies, but generally the most common are low-frequency (LF, around 125 KHz), high-frequency (HF, 13.56 MHz) and ultra-high-frequency (UHF, 860-960 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequencies, so it's important to choose the right frequency for an application. In general, LF and HF RFID systems rely on non-radiating near field coupling and have relatively short range. UHF and microwaves radiate and therefore have much longer range.
Active RFID tags have a transmitter and their own power source (typically a battery). The power source is used to run the microchip's circuitry and to broadcast a signal to a reader (the way a cell phone transmits signals to a base station). Passive tags have no battery. Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, but communicate by drawing power from the reader. Active and semi-passive tags are useful for tracking high-value goods that need to be scanned over long ranges, such as railway cars on a track, but they cost more than passive tags, which means they can't be used on low-cost items, and their life is limited by the battery. (There are companies developing technology that could make active tags far less expensive than they are today.) End-users are focusing on passive UHF tags, which cost less than 40 cents today in volumes of 1 million tags or more. Their read range isn't as far, typically less than 20 feet versus 100 feet or more for active tags, but they are far less expensive than active tags and can be disposed of with the product packaging.
| Active RFID | Passive RFID | |
|---|---|---|
| Power | Battery operated | No internal power |
| Required Signal Strength | Low | High |
| Communication Range | Long range (100m+) | Short range (3m) |
| Data Storage | Large read/write data (128kb) | Small read/write data (128b) |
| Per Tag Cost | Generally, $15 to $100 | Generally, $0.15 to $5.00 |
| Tag Size | Varies depending on application | "Sticker" to credit card size |
| Fixed Infrastructure Costs | Lower - cheaper interrogators | Higher - fixed readers |
| Per Asset Variable Costs | Higher - see tag cost | Lower - see tag cost |
| Best Area of Use | High volume assets moving within designated areas ("4 walls") in random and dynamic systems | High volume assets moving through fixed choke points in definable, uniform systems |
An RFID antenna is attached to the RFID reader and is the radiator that emits radio waves. For passive tags, this enables the tag's antenna once it has entered the RF field to power up its microchip to send and receive RFID data. The type of RFID antenna determines the type of RFID field generated. Circular-polarized RFID antennas emit radio waves where the polarization rotates in time and space around its radiation direction and are used when the orientation of the tag to the reader cannot be controlled. Linear-polarized RFID antennas focus the radio energy in a single polarization direction. Although this increases the read distance and provides greater penetration, the tags must be aligned with the RFID antenna's polarization direction in order to be read. Most RFID readers need an external RFID antenna for use, although some units are integrated (reader & antenna in a single product). RFID antennas for fixed RFID readers have a longer range and tend to have more gain than the RFID antennas found in portable RFID readers.
An antenna normally has one single beam or main direction of power flow, and the polarization is transverse to this direction. If a tag is aligned parallel to this power flow direction, it will not be seen by the reader system because the antenna can not fundamentally have a polarization in this direction. To correct this situation, one needs multiple beams or power flow directions coming from the same antenna. This way, all the tags can be read independent of their orientation and position. Thus, the NeWave antenna was designed to have five beams that criss-cross in the region surrounding the antenna. Each of these criss-crossing RF beams of energy appears to emanate from the full length of the antenna and fills the near zone region in circular patterns surrounding the antenna. As a result, the NeWave antenna optimally covers the full zone in its near vicinity.
There is a fundamental term that characterizes the antenna size needed for each frequency. It is known as the wavelength, which is nearly 100' at HF and about 1' at UHF frequencies. Clearly, one cannot think about a radiating system at HF because of its enormous size. Thus, HF systems have been based on what is known as near field coupling, which means that the reader antenna is not a radiator but a near-field coupling unit that must be located close to the tags, say within 1' or 2', so that the tags are properly excited. On the positive side, these near field coupling systems tend to work even through water and dense materials. Also, the tags can be rather small, which is useful for smaller items.
On the other hand, one can use a true radiating system at UHF frequencies because it will not result in an unobjectionable antenna size. Since it is a radiating system, it will have a much greater range of coverage, say from 10' to 100'. In our case, the NeWave reader antennas were specifically designed to uniformly cover a zone that ranges from 2' to 10'. These zone sizes are needed for item-level applications in that they cannot be too large or they do not define the location well, or too small in that it is cost prohibitive. For example, the NeWave antennas can even be used on metal shelving systems and cover a complete 8' length, front and back as one zone. This could not have been reasonably done using HF frequencies.
The patch antenna was originally designed for medium range communication systems. For example, it is used today as a microwave link with a range of say 3 to 5 miles. So clearly, it was not specifically designed for RFID applications. In this regard, one can think of the patch as a telephoto lens in optical terms. Since RFID is meant to work at much shorter distances, especially for item-level applications, the patch is not ideal. This has lead to comments like, "I cannot read a tag at 4 feet, but I can at 30 feet." This happens because the patch has one beam, which can only cover two of the three fundamental orientations of the tag. Thus, it can not see the tag at 4' because of its orientation, but it can see the one at 30' because it is the equivalent of a telephoto lens. As a result, there has been a great need for a new reader antenna that is specifically designed for RFID applications.
The NeWave antenna was specifically designed as an RFID item-level reader antenna. To illustrate this point, there has been a great interest for many years to have an RFID system that works on metal shelving systems, which represent about 75% of shelving in the US. Clearly, the patch antenna is not appropriate for this application in that one does not need the equivalent of a telephoto lens. One needs something more like a fish-eye lens that sees everything around it. Thus, we created the NeWave antenna with this in mind such that the NeWave antenna provides full coverage completely around its long axis. It is long in one dimension to create multiple beams that have different power flow directions and polarizations. In the near-field, the NeWave antenna creates various plane waves that emanate from the full length of the antenna and criss-cross filling the complete region in the near vicinity of the antenna. Thus, one can place a tag in any position and orientation in its coverage zone and the NeWave antenna should see it. Of course, one antenna can not see all the potential tags in its coverage zone because of fading (meaning that environmental scattering and blockage cause signal drop-out positions within a region of coverage, much like observed for mobile phone applications). To solve this fading problem, one has to apply as much diversity as possible. For the NeWave antenna, it automatically provides beam (or direction-of-arrival) and polarization diversities. Thus, one only needs to use multiple antennas to provide additional spatial diversity. For a fixed application, like a metal shelf item-level case, one needs four NeWave antennas to completely cover the zone. For portal applications, typically two antennas are needed. Thus, the NeWave antenna is dramatically different than the patch and specifically designed for an extremely wide variety of RFID applications.
A patch antenna creates a directive beam of RF energy and is designed for long-distance communication. It might be able to read an RFID tag at a great distance if it lies within the beam, but also might miss a tag up close simply because it lies outside the beam or its polarization is misaligned. Item-level RFID requires the capability to read tags in the immediate vicinity of the antenna in all possible orientations. For this reason the NeWave antenna was designed to provide uniform coverage in the zone surrounding the antenna, out to a radius of about 10'. Furthermore, the NeWave antenna has built-in polarization and beam diversity to overcome fading and polarization mismatches. It would require up to four patch antennas to uniformly cover the same volume as one NeWave antenna and achieve the same field diversity. A good example is the metal shelf application. Using patch antennas, at least one patch would be required on each shelf because the metal blocks the signal from other shelves. A single NeWave antenna can cover up to 7 vertical feet of shelving because it radiates uniformly along its length.
With their uniform coverage and field diversity properties, a set of 2-4 NeWave antennas has been shown to provide superior read rates over a given volumetric zone compared with a similar number of patch antennas. Typically, greater than 99% read rates have been demonstrated for real applications with large numbers of tagged items. To achieve the same performance with patch antennas, more antennas or a higher radiated power would be required. However, due to the long-distance property of the patch, these antennas would be reading tags from many other nearby zones and making it very difficult to locate a given tag.
The NeWave antenna is not recommended for RFID applications requiring long-distance tag reading. The maximum effective range is about 10' with reader output power between 20 and 30 dBm.
The certification process is still in development. We currently have installation guidelines that we send to our partners and customers. We have been developing a complete certification process that will be conducted annually in Ohio at our Innovation Center. So far most of our partners have been able to get good results with over-the-phone training. The level of training will of course depend on the systems integrator's understanding of radiating systems.
The NeWave antenna can be used with any reader system. Thus, one only needs the RF cables that go from the reader system of your choice to the antennas. Our antennas use a reverse TNC connector and we supply cables with reverse TNC connectors on both ends in specific lengths from 5' to 20'. So the cabling is very simple.
The reader system used with our antennas is completely your choice. Thus, you can choose one that best fits your needs, such as POE and/or wireless. The RFID reader will not interfere with other wireless devices.
The NeWave antenna has been specifically designed to cover a range from 2' to 10'. However, any radiating system will tend to see beyond this range in that one wants to read all the tags in its coverage zone. So outside this zone, it sees some but not all the tags. Therefore, one has to deal with what we might call out-of-zone tag reads. These reads have typically been classified as system failures. This does not make sense for the following reason. It is our desire to make sure that we read tags much like a normal radar application where we must see a dangerous target. Thinking in radar terms, who would say that their solution failed because it saw the target on two different radar systems? The same thing is true here. We want to see the tags.
So, how is this situation resolved? It is a simple matter to collect the tag data at a central computer site. Then where there is an issue of multiple tags reads, one simply determines the proper zone by comparing the RSSI (received signal strength) levels and/or tag read rates. Since the tag is located clearly in one zone, this zone data will have much higher RSSI levels and read rates as compared to the out-of-zone results. One final very interesting note is that one can begin to determine whether a given tag is located very close to the border between zones. In this case, the RSSI levels and read rates will be very similar for both these zones. Therefore, one can use this information to provide even finer resolution than indicated by the zone coverage size of the antennas. This is a powerful tool for RTLS applications.
The NeWave (zone coverage) antenna system has been specifically designed to provide complete coverage within a zone. The antenna deployment concept handles the fading issues in an optimal way. As a result, one can use much lower power levels than have been used in previous patch based systems. This becomes a very important issue in that one has to set very high power levels for patches in order to handle the fading, but these very high power levels result in reading tags at very large distances. The NeWave antenna does not have this problem because it directly solves the fading using multiple diversities much like done in mobile phone systems. Since the fading is naturally solved within the antenna system design, one can use much lower power levels and greatly reduce the long range reads formerly seen using patches.
The number of Wave™ antennas needed versus the number of patches depends on a given application. A list of application variables includes types and method of items being tagged, distance between antenna read points, stationary versus items in motion, type of patches used, spacing of patches, patches used in an array, power levels used, mounting considerations etc. A good rule of thumb is each Wave™ antenna has a minimum of five criss-crossing beams and each patch antenna has one directional beam. Although one cannot absolutely correlate on a beam for beam basis, as beam width, placement and power levels vary greatly, we can say confidently that the total cost and ease of installing Wave™ antennas versus patch antennas to achieve comparable technical results will be lower for most applications.
The NeWave antenna comes in three sizes, 3', 5' and 7'. For each of these antenna sizes, one can purchase the antenna in a casing or simply as an embedded radiator section. This embedded radiator is already completely mounted on one thin film and easily integrated into various structures. If you are not familiar with using composite embedded structures, we have tremendous background in this topic and can provide the support needed for your desired application. One can envision using the embedded antennas in shelving systems, portals, tables, desks, walls, file cabinets, vehicles, etc.
The NeWave antenna has been optimally designed to work in harsh environments like metal shelving systems. In these environments, the problems result from very complex scattering that creates tremendous fading issues. For example, one may not only have to deal with the metal shelves but also the many liquid and metal contents found within the items located on these shelving systems. This is especially true for most of the items found on the Organized Retail Crime lists. Therefore, this is a very serious issue.
With all this potential fading within the environment, one has to better understand how the NeWave antenna system works. Each NeWave antenna provides beam (direction-of-arrival) and polarization diversities. Spatial diversities are provided using multiple antennas to cover a zone. These diversities are the same as those used in mobile phone systems, which have been continually refined to provide better and better service. We are using this vast knowledge in our antenna systems. This being the case, the fading caused by the metal shelving and/or items is handled in the same way using all the diversities. With these diversities, one can handle very complex scattering environments. In fact, boxes and other items can be stacked right up next to the antenna without affecting its performance. This is because the NeWave antenna is a distributed radiator, meaning the radiation comes from the entire length of the antenna rather than from one spot. Blocking part of the antenna will not affect the radiation from the other parts. A point radiator, such as a patch antenna, could be completely blocked by a single item sitting in front of it.
Now there are harsh environments related to dealing with hazardous waste materials, harsh warehouse cases, outdoor applications, etc. Our initial product line was devoted to indoor item-level applications that avoided these harsh environments. However, we have more recently developed new products that can handle these cases as well. In fact, it uses our unique composite and exotic material expertise to solve these issues in a very cost-effective and novel way. If you are interested in these very unique products, please contact our sales force at 888-677-7343.
From the start of our RFID antenna development, we found that our item-level applications typically resulted in having four antennas per zone. Since the cost of the antennas is much less than the reader, it makes great sense to put as many antennas as possible on one reader until the total cost of the antennas is about equal to that of the reader. This being the case, 16 antennas was found to be ideal. It even makes more sense, when each port of a typical four port reader can be used as a NeWave coverage zone. To implement this solution, one uses a remote set of RF switches to fan-out each reader port output into four ports, which are digitally controlled by the reader GPIO. The reader is software-controlled to sequentially read through each of the sixteen antennas. Then through software processing, the four antenna results per port are combined together to properly define what items are found in each NeWave coverage zone. Using this approach, one can use a wide variety of readers and have considerable savings in the resulting infrastructure cost associated with an application. For example, we have found using this approach that one can cover a complete 32' shelving section using just a single reader and 16 NeWave antennas and the items can be found to a resolution as small as a 4' section.
Patch antennas can be bought for as little as $35 and as high as $280 depending on several factors. On an apples-to-apples comparison, we estimate the number of patch antennas needed to get the same results as NeWave antennas would result in comparable total costs. Therefore, the performance of these two antenna solutions is the most significant issue.
The NeWave antennas are presently warehoused in Columbus, Ohio and can typically be shipped the next day to any place in the US or Canada.
The NeWave antenna is continually being certified by more and more reader companies as they see its tremendous value. Please check with us relative to your proposed application if you have any concern about this issue.
The Smart Shelf places the RFID tags on the item dispensers or shelf. Then the item either naturally blocks the RFID signal or a thin metal is added so that the item blocks the tags underneath it. Using this concept, one can easily and very cost-effectively determine whether an item is present or not on its retail shelf. It is interesting that most of the Organized Retail Crime (ORC) items naturally block the Smart Shelf tags, which makes the Smart Shelf ideal for ORC applications.
The most popular way to install Smart Shelf is to have the tags integrated into the shelf dispenser trays. These trays are used to align the same items in columns and to impede ORC cases in that one can only remove one item at a time. These dispenser trays then have a bar code on the front to indicate what is normally found in this dispenser. Besides this bar code, we can add a bar code that is used to define the RFID tag numbers contained within this dispenser tray. So the process is to first scan the item bar code to tell the system what item is being loaded onto the dispenser. This can then be immediately followed by reading the dispenser bar code. These two bar code reads will then be used by the software to interconnect the item information with the dispenser RFID tag numbers. This way, one can place whatever item he or she wishes to place in a specific dispenser. This makes the process very simple and more-or-less follows their standard restocking procedures.
The portal designs follow a dramatically different approach than what is traditionally found in the RFID marketplace. Presently, portals use a two part process. The first part is a heavy metal structure that is used to hold, position and aim the patch antennas. The second part is basically what the antenna engineers call a radome, which is used to cover and protect the inner or first part as discussed earlier. Because the radome is used to protect the internal parts it must be structural but at the same time not interfere with the RF energy going through from the internal antennas. This is an old concept that has been around since the very first antennas were developed and it's still used to today in many applications.
Our approach is based on modern antenna designs that use very sophisticated composite structures. In this approach, one realizes that the two part construction process that was discussed earlier must be combined into one part. However, this requires that the internal antenna can not be modified in terms of its position or orientation; plus, the antenna structure itself must be structural. NeWave antenna systems have been designed such that they naturally do not need any position or orientation adjustments after the portals are built, so this solves the first issue. Next, the foam within the NeWave antenna can be replaced with a very exotic structural foam material. For purposes of understanding, one can think of the very special foam found in the dash board of a car. Once the NeWave embedded antennas are combined with this exotic structural foam, we can easily and very cost-effectively create a very unique portal system that is much lighter, lower cost, significantly easier to install and in many cases higher performance. Further, a very simple, extremely durable and highly decorative cover can be used to hide the internal portal structural foam antennas and wall or floor mounting structure. Thus, making it very attractive as well.