Active & Passive RFID 101: The Basic Differences

RFID or Radio-Frequency Identification (RFID) is a wireless communication system which uses radio waves to identify and track objects, animals, or humans. Although ignored in its earlier years for being too expensive, RFID has found a new lease of life in recent years. Widespread adoption of RFID is being seen across multiple industries. Significant advances and newer innovations in the RFID technology are making it more accessible and prominent in our lives. RFID is powering several industries and is the main driving force behind the IoT. Several industries like retail, transport, health, and defense are heavily investing in the RFID technology to streamline their processes and increasing efficiency. RFID sector is experiencing a new high.

An RFID System

A RFID system consists of two parts: a RFID Reader and a RFID Tag. Furthermore, there are two broad categories of the RFID system: Active RFID and Passive RFID. Although both of these technologies are often considered together, fundamentally they are distinct from each other and offer significantly different capabilities. Active RFID system is battery powered whereas Passive RFID system does not have a battery. The other main notable difference between the two technologies is the cost. Passive RFID is cheaper than Active RFID.

Differences between Active and Passive RFID Tags

Both Active and Passive technologies use radio frequency energy to communicate between a tag and a reader but the method of powering the tags is different. Simply speaking, Active RFID uses an internal power source (battery) within the tag for its RF communication whereas Passive RFID does not have its own power source but relies on RF energy transferred from the reader to the tag to power the tag. Passive tags and labels are smaller allowing them to be used widely, whereas Active tags are larger (due to the presence of battery and onboard sensors) and much more expensive.

Active RFID

As mentioned earlier Active RFID system uses battery-powered RFID tags to transmit its own signal. So, an active RFID tag consists of a battery, and an active transmitter. Since the active tag has its own power source it does not depend on the reader signal to generate a response. Active RFID Tag is capable of receiving very low-level signals, and then generating high-level signals back to the reader. Moreover, the Active RFID tag is continuously powered. Active tags can also transmit a periodic beacon to a reader (or other tags) in certain situations. The presence of own power source in Active tag allows it to have extremely long read ranges, with read distances of up to 100 meters or more seeming quite common. The presence of onboard power source also bestows the tag with large memory. Active tags may be either read-only or read/write, thus allowing data modification by the reader. Since Active tags can be read at much greater distances they are able to collect thousands of tags from a single reader. Additionally, some Active tags can contain external sensors to monitor temperature, humidity, motion, and other conditions. Due their long reading range, Active Tags are ideal for applications which require long range scanning. Active tags operating at 433 MHz are most common active tags which can be used to track goods trains or large military assets. These tags can also be used in logistics, tracking ocean containers, vehicles and other large and high value assets. Active Tags (2.45 GHz) are often used in toll collection as well as in Real Time Location Systems (RTLS) for locating assets within a facility such as a warehouse, a hospital, or an office building.

Passive RFID

Passive tags have no battery, instead, they draw power from radio waves received from the reader. Since the passive tags do not contain a battery and depend on the reader signal or the backscatter to generate a response, their read range is not as strong as an active RFID tag; they have a read range of not more than 10 meters. Moreover, the read speed is also slow. As the power is available only within field of the Reader, Passive RFID has limited read/write data storage. However, since Passive RFID does not contain a battery or a transmitter, it is small in size, lighter and less expensive than the more powerful active tags. Moreover, Passive RFID Tags have a larger life span. Passive RFID System generally comprises a RFID reader, RFID antenna, and RFID Tags. The system can operate in the low frequency (LF), high frequency (HF) or ultra-high frequency (UHF) ranges. Passive RFID Tags are available in various shapes and sizes and are easy to attach; sometimes they are embedded into adhesive labels. These tags are disposable and hence are ideal for applications where reusable tags are not needed.  DVD kiosks, IT asset tracking, file tracking, laundry management are the typical applications of Passive RFID which do not require a long read range. Active RFID and Passive RFID both have their advantages and disadvantages. Your decision to choose active RFID or passive RFID system will likely depend on your specific requirement, performance of the system, other use parameters and total cost of deployment. Depending on your application requirements, you can opt for either of the two or even go for a combination of the two.]]>

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