RFID development trend and various differences between UHF Gen 2 RFID and HF RFID
If you are considering HF RFID technology instead of UHF Gen 2, then you have to ask yourself first, why? UHF Gen 2's current performance on small units on a high-speed production line is already comparable to the performance of container pallets in freight centers. Due to the low cost, UHF Gen 2 has led to the old, slow and costly HF 13.56 MHz RFID technology on the verge of being eliminated.
Before deciding which radio frequency identification technology to deploy, you need to understand the basic concepts of UHF and HF.
Radio frequency waves contain two components: magnetic waves and radio waves. Generally, HF RFID 13.56 MHz relies on the "near-field" magnetic field in the electromagnetic field, while UHF RFID 860-960 MHz is far-field radiation, including both magnetic and electric fields. What kind of wave responds to UHF tags depends on two aspects: the distance between the tag antenna and the reader.
Since the intensity of the magnetic field component in the wave will decrease rapidly with distance, it can only work in the near field. Its effective range is limited to about one or two wavelengths by the antenna structure. In order to receive energy, the HF tag uses inductive coupling to induce the magnetic field. HF tag antennas are usually inductive antennas that are somewhat like coils, so more conductive materials and more complex manufacturing processes than equivalent UHF tag antennas are required. Fortunately, the HF tag has no dead angle above the magnetic field. Using a suitable antenna, the UHF tag can easily obtain the same near-field energy, and is more efficient and cost-effective.
The four equations of Maxwell are the foundation of electromagnetic field analysis and design. Faraday's law is one of these four equations: "The voltage induced by the coil in the magnetic field is proportional to the strength and frequency of the magnetic field." This reveals an extremely simple concept: the higher the frequency, the higher the efficiency. The frequency of UHF is 60 times that of HF, which means that for the energy coupling efficiency between the tag and the reader antenna, UHF is about 60 times that of HF. This is an indisputable physical essence.
The traditional concept is that UHF is not suitable for item-level labels: the label is too large, UHF can not work on liquid, metal and small single item packages close to each other. And UHF is too far away, all of which ignores the fact that UHF Gen 2 can be used in the near field more easily and efficiently than HF. This means that UHF systems can read many things that HF ​​can read, including items with high levels of liquids and metals. More importantly, this means that single-grade applications have been able to balance the various benefits that the UHF Gen 2 standard brings to the supply chain.
The key is how to control the near field of UHF. This component of the radio frequency wave is especially suitable for the work of single-grade RFID in close proximity. Various applications using near-field UHF Gen 2 solutions are growing.
RFID and the frequency debate
In December 2004, EPCglobal approved the UHF Gen 2 protocol, resulting in the first global RFID standard. Since then, many products that meet this standard have been seen on the market. This popularity proves the universality from single items, containers to trays, the objects used are in the near field and the far field, the material covers liquid, metal, tightly packed and packed items, and so on.
Three years later, HF product developers had to recognize the standard. On the contrary, the latest HF specifications have dispelled the drafters' illusions. According to Ken Laing, the standard compiler of HF "V2" (HF version of UHF Gen 2), the progress of work so far has been limited. The only progress is the limited improvement of existing standards and the emergence of some commercial products.
Compared to encoding EPC on the currently popular HF standard-ISO 15693, Laing believes that companies that encode EPC on the Gen 2 HF label will see performance improvements. He said that according to the results of the RFID Update, although the improvement is not earth-shattering, it is still much better than the HF products currently on the market. Perhaps an important point is that even if the standard has been approved, the so-called qualified V2 product will not meet it at the beginning, and this phenomenon will last at least one year. This will take a long time, and even if it can be used now, it will not reach the current performance of UHF Gen 2.
Figure 1: The difference between UHF Gen 2 and HF coverage area.
However, this article returns to continue to look at the frequency debate, because this is related to the actual deployment.
Consider the following factors:
* UHF Gen 2 covers all applications in the global supply chain;
* UHF Gen 2 is effective for all types of product materials, including liquid and metal materials.
So for UHF Gen 2, HF RFID technology is redundant because:
* Nothing can be achieved by HF but not by UHF;
* And many HF can not achieve, but UHF can. HF can only solve a small part of the UHF RFID field.
For RFID applications, UHF is the "superset" of RFID. Products that comply with the standard can solve a variety of projects, containers, trays, all materials and packaging types, and provide much higher throughput than HF.
A properly deployed UHF Gen 2 system, whether large or small, or liquid or metal, will work very well. As on containers and trays, it can effectively eliminate HF before the near-field UHF Gen 2 appears. Has the advantage of single item level. It is true that liquids can absorb RF energy, and metals can reflect RF energy, but this is all a matter of consideration in the far field, and it is another matter for the near field. In fact, since a properly designed UHF tag antenna can be used in the near and far fields, it can actually use the attached metal as an extension of the antenna! But HF tags are not good because they lack the means of electric field coupling. Nonetheless, we will discuss in depth the practical impact of deploying HF RFID systems.
At first, HF could not realize far-field applications, which meant that it could not be used in warehouses and logistics centers that needed RFID containers and pallets for long-distance work. Therefore, the application distance of HF was limited to near-field.
Therefore, enterprises that choose HF as item-level label identification must also deploy UHF Gen 2 to identify containers and trays. Nowadays, multi-channel data bearing architecture, cost, complexity, efficiency and maintenance are also considered. So, if you think that digital logistics is not difficult, you have to run into the wall. These also require us to consider some economic factors: UHF Gen 2 tags will always be cheaper than HF tags. In fact, because UHF tags are easy to manufacture, they will be 2-3 times cheaper. Unlike HF tags, UHF Gen 2 tags are particularly suitable for simple, high-speed manufacturing technologies with particularly good process upgrades. Thanks to the simplicity of UHF Gen 2 and the single-layer antenna structure, it can be manufactured using an inexpensive conductive ink process. UHF is a very practical and economical band that meets the standards. In fact, the same UHF Gen 2 chip designed for long-distance use on large trays can also be used with a near-field antenna as small as about 6mm-this tag is much smaller and cheaper than the previously widely used HF tags Much more, and can also provide better performance.
Another advantage of the UHF antenna structure is that when items are stacked very close together, UHF tags will not place an RF "shadow area" on adjacent items. This is not the case with HF tag antennas. The antenna consists of a thick metal coil, which can form a magnetic shield to the adjacent tags, thereby allowing the reader to read. Therefore, UHF has more reliable performance.
The continued development of UHF Gen 2 technology will further widen the gap between its cost, performance and functions with HF technology, and this gap will definitely not be able to make up for this gap. This is the basic point, because the economics of UHF Gen 2 actually benefit from the physical characteristics of the UHF band. For RFID work, the efficiency of the UHF band is 60 times that of the HF band.
If the goal is coupled communication between tags and readers, UHF is superior in many respects to weaker HF solutions. Because UHF Gen 2 has high speed, high reliability, and flexibility of operation. This is why the conclusion of Blue Vector's CEO-Nancy Anderson, "We will not use HF anymore because it is not as flexible as UHF".
Cardinal Health's Julie Kuhn, the manager of Pedigree, explained this to me. "You can't use UHF tags to achieve UHF tag reading speed. This means that our conveyor belt can't be faster than the slowest reading rate." This is a big limitation that will affect the distributor's order throughput rate. “It ’s now,†she continued, “we ’ve been ordering until 8 pm, and orders have been dispatched from 5:30 in the morning. This complex UF / UHF architecture will restrict our ability to maintain the bill of lading replenishment time†.
This aggravates the problem of multi-protocol architecture. And unfortunately, using devices that can read HF and UHF tags at the same time-that is, multi-protocol RFID readers to solve these problems will only cause more problems. These problems include more complex readers, higher costs, more precision, and lower reading rates, and also reduce the reading reliability, because the interrogator must periodically cover multiple protocols, so the reading is always Need a compromise. When multiple data-bearing protocols are used, these problems will occur in the supply chain.
When Gen 2 solves these problems of competition and incompatibility with the UHF standard, the HF technology itself also has these problems. Related standards currently in use include ISO 14443, ISO 15693, and EPCglobal HF Class 1. Depending on the selected technology and standard, for deployment, maintenance and upgrade of a hybrid system architecture, it is needless to say that the need to manage their respective data formats, even from the economic and logistics itself, there is no support for separate UHF and HF architectures What meaning.
The continuity strategy ultimately adopted by the company has a significant impact on downstream trading partners and will gradually penetrate the entire supply chain. This scenario is emerging in some medical fields today, and the hybrid protocol system used here is hindering the reliable throughput of goods. Julie Kuhn added, "We are concerned about how to combine all technologies into a single technology to form a highly automated environment in which we can obtain the genealogical information of the goods at the single product and container level, and maintain our existing high Throughput rate. "
Table 1: Functional properties of UHF Gen 2 and HF.
The field of medicine is not the only field that has this problem and draws the above conclusions. For example, consider a well-known item-level garment factory-Lemmi. Lemmi RFID solution provider-Reva's Ashley Stephenson, explained how to switch from HF technology to UHF technology that is more flexible, faster, cheaper and has better performance. "When you read 100 pieces of clothing, UHF can read them all at 10 times the speed of HF. The cost of UHF tags has dropped significantly, which is a trend that is continuously expected. UHF technology providers like Impinj have already adopted this technology. Invested and actively promoted the distinctive UHF technology called near-field. This technology expands the range of UHF architecture options. At the beginning, HF was used in the clothing and retail fields, but now and all are turned to UHF Gen 2 The standard. The pricing of UHF Gen 2 clothing tags is much lower than that of HF tags, and UHF readers can also provide near-field and far-field options, which can accommodate most reading distances.
Louis Bianchin, a project manager at Venture Development and a senior RFID analyst, believes: "UHF Gen 2 RFID is currently the most outstanding technology in supply chain applications. For example, the deployment in the pharmaceutical supply chain has proved that the technology can provide reliable, High-speed tracking across the entire supply chain-even under very demanding conditions. Successful deployment in the pharmaceutical industry is expected to lead the application in other markets.
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