Passive RFID

Introduction

An RFID system is a wireless method to identify and track tags. These tags can be mounted on goods, products that are of costly nature, on humans and animals, and similar other moving objects. In animals and humans, tags can be embedded under the skin. RFID tags are known as being ‘non-contact’ and ‘non-line-of-sight’ as they don’t require you to swipe any card for identification.

A Passive RFID tag is a tag that does not include a battery unlike Active RFID tags; here the reader supplies the power. They operate by using the power from the RFID transceiver. The absence of an onboard power supply implies that the device is quite small. One can find commercially obtainable products that can be implanted under the skin. The smallest of these devices that have been experiential are measured to be 0.15 mm × 0.15 mm, and are said to be slender than a normal sheet of paper (at approximately 7.5 micrometers).

When a Passive RFID chip experiences a convergence of radio waves from the reader, a magnetic field is formed within the coiled antenna. Power is drawn from the tags and the circuits are energized and the encoded information that has been stored in the tags memory is sent across.

Frequencies

RFID systems can operate across an extensive range of frequencies. Lower frequency systems are less expensive; higher frequency systems fall in the increased range. 300-500Khz is considered to be a low frequency, while on the other hand 850-900MHz and 2.4GHz-2.5Ghz are said to be relatively higher frequencies.

Uses

1. RFID systems are used in shopping malls, bookstores, attached to apparel, cosmetics, jewelry, books, etc. The white little tags hidden in these items enable retail EAS (Electronic Article Surveillance). This prevents or at the least counters the menace of shoplifting.
2. RFID systems are also employed to automatically pay highway tolls are these tolls are high frequency systems.
3. Passive tags are also employed for animal tracking and in places where power is unavailable and the expenditure for a tag is more vital than its range.

Advantages

1. As the tag performs without a battery, it has a useful life of twenty years or more.
2. Since the manufacture of these tags is not an expensive affair, these tags are relatively small and inexpensive for the pockets of the buyer.
3. Passive tags can be as small as the size of a grain of rice. And owing to their tiny size, they have unlimited uses and applications in areas such as consumer goods and consumer durables.

Disadvantages

1. Whereas a battery powers active RFID tags, Passive tags utilize power the RFID transceiver.
2. Also as compared to active tags, passive tags do not have a good range.
3. In comparison to Active tags that can store up to 1MB of data, passive tags can only manage 32 or 128 bits of data.
4. Another less favorable point for Passive tags is that they are Read-Only, whereas active tags are rewritable. (Though it is being said and the technology being worked upon for passive tags to be read/write enabled, permitting them to act as transportable databases and hence allow product information to be associated to the labeled item.)
5. Unlike Active tags, which can be read at a range of 300 feet, passive tags have a very limited and small range and can be read at a few feet at the most.
6. It may or may not be possible to take in sensors that can use electricity for power like in active tags.
7. The tag can be read for a long time. For e.g.: After a product is sold to which the tag was attached, the tag continues to be read in spite of it no longer being tracked.

Pros and Cons Measured

With RFID (Radio Frequency Identification) now becoming a booming new wireless technology with enthusiastic new spectators, the retailers, RFID is now being custom-made to follow inventories via microchip-tagged products. Semi Passive RFID patents are also filed with the government. And with this growing interest in this technology, a debate has sparked up as well as to the correct usage of it and certain privacy rights of individuals. Some privacy concerns are:

1. A buyer might not necessarily be conscious of the presence of the tag or be able to discard it.
2. The tag can be read at a distance without the learning of the person. Eavesdropping can be an easy task and to a layman RFID technology will be seen as another device for bugging.]

One must be well versed before jumping in into trying out a new technology as it may have many undiscovered potential uses that can be misused. However, RFID technology is gaining maturity and wide acceptance in various industries and can be considered a strong candidate for your manufacturing automation.