Friday Fundamentals: RFID Tags


In its simplest form, an RFID tag includes two parts:

  1. An antenna for transmitting and receiving signals
  2. An RFID chip (or integrated circuit) that stores the tag’s ID and other information

They can be affixed to just about anything, allowing that item to be actively or passively tracked in real time. When an RFID tag is read by a properly calibrated RFID reader, the resulting event can produce a wide array of results, such as:

  • Updating a database
  • Recording a transaction
  • Tracking movement of the tagged item within a monitored space
  • Allowing access to a secure location (RFID ID badges)
  • Triggering additional actions (security alarms, inventory resupply orders, etc.)

Due to their flexibility and relatively low cost, RFID tag-based systems have become commonplace in numerous industries, and are heavily connected to existing and emerging internet-of-things (IoT) technology. 

How to select the appropriate RFID tag

RFID tag selection is one of the most important aspects of a successful RFID system implementation because the wrong tag can eliminate the value of even the best-designed system.

It’s not a quick, simple process either, since there are hundreds of tag variations available on the market today. They can be broken down into two main categories: Active and Passive.

Active RFID tags

Active RFID tags are powered by internal batteries, and therefore produce a strong signal that is more easily read by readers. As a result, they can be read at distances as far as 750 feet and offer very high readable reliability, even in difficult circumstances (such as when the tagged item is moving at a fast pace or is blocked by walls or a lot of other materials.) They can also facilitate more data storage than comparable passive tags.

While these are some powerful pros, the downside of active tags is their higher cost (often upwards of $12 per tag), larger minimum size, and somewhat limited use cases.

Active RFID tags are appropriate for long-term use in high-value applications such as vehicle tracking, toll collection, and inventory tracking of very high-value items.

Passive RFID tags

Passive RFID tags are not internally powered, but instead draw the power they need from the signal sent out by a nearby reader. As a result, they need to be much closer to the reader. Line-of-sight is still not necessary, but far less obstruction can potentially cause a read failure. 

While it may seem at first glance that active tags are dramatically superior, these differences allow passive tags to range in sizes as small as fractions of an inch, and cost mere pennies apiece. 

Passive RFID tags are appropriate for many uses including tracking of consumable inventory, access control applications, inventory and supply chain management, and workflow process monitoring.

What to consider when choosing an RFID tag

When selecting an RFID tag for a given application, cost will necessarily come into the conversation. However, other questions need to be answered first in order to ensure the most cost-effective option is actually going to accomplish the purpose you’re setting out for it.

  • What type of surface will you be tagging? (Metal, plastic, wood, etc.)
  • What read range do you desire? (Inches? Feet? Yards?)
  • Are there any size limitations?
  • Are there environmental conditions to consider? (Excessive heat, cold, moisture, impact, etc.)
  • How will the tag be attached? (Adhesive, epoxy, rivets/screws, cable ties, etc.)

How to make sure you’ve picked the best RFID tag

The best way to ensure you’re selecting the very best tags for your application is to work with experts who have the opportunity to evaluate your location and test multiple tags under appropriate conditions. This is part of a standard site survey that any RFID consultant should be willing and able to perform. 

The next best option is to purchase your RFID tags from a reputable source where you have the opportunity to discuss your needs in detail with an expert who can guide you to the very best option for you. 

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