Frequencies Tutorial

Let RFID Inc. get you up to speed on the basics.

125 KHz to 148 KHz

Click here to download a tutorial powerpoint with application photos

This frequency range was the RFID industry’s first, since the early 1980’s. Typical applications include:

  • Access Control & Security.
  • Identifying widgets through manufacturing processes or in harsh environments.
  • Ranch animal identification (ISO 11784/11785).
  • OEM applications.

Tags are made of a hard copper coil and eeprom chip then packaged into a housing appropriate for the application.

Tags can cost from $1 to $75, highly dependent upon quantity and packaging. The more robust a Tag is, the higher its cost. Less expensive Tags are typically flimsy and will not survive harsh environments. Custom Tags, the tooling of eeprom silicon wafers specific to an application, can result in a Tag price of 20 to 30 cents, in quantities of millions.

Read ranges are typically inches to several feet.

Although Tags can be placed on metal and embedded into metal with some loss of performance, the KHz spectrum is the most adaptive to a metal environment. No RFID Tag can read through metal.

13.56 MHz

In an effort to lower Tag cost and address applications of high quantity Tags usage, the 13.56 MHz solution was born. At this frequency, a Tag’s coil need not be made of hard copper wrappings. The coil can actually be a printed ink on a paper like substrate which than has an eeprom added to it. During the mid to late 1990’s, 13.56 MHz was the vogue technology that many experts saw as a path to addressing high quantity applications necessitating low Tag costs. Typical applications include:

  • Library books.
  • Laundry identification.
  • Access Control.
  • OEM applications.

Typical Tag costs range from 50 cents to $1 unpackaged. Tag prices can dip to the 20 cent level if custom eeprom silicon can be committed to by the user.

Read range are typically inches to several feet.

Metal poses a serious source of interference and loss of performance. Mounting Tags on metal can pose very challenging. The

advent of 915 MHz technologies and new manufacturing capabilities at the 125 KHz spectrum have lowered the anticipated explosion of 13.56 MHz as an accepted technology, however 13.56 MHz will always have its niche applications especially in the OEM market.

915 MHz

Since the early 2000’s, 915 MHz has been all the rage, the vogue technology of frequent press bringing the RFID industry into a global limelight, the epicenter of development efforts and dollars. Tags at this frequency also need not incorporate a hard copper coil. Coils are also much less difficult to manufacture versus 13.56 MHz and 125 KHz, which is not its only advantage. Hundreds or even thousands of Tags can be identified at the same time, a term known as anti-collision, at much greater distances, 10′ with a single Reader Antenna and 20′ between two Reader Antennas. Although Tag costs can be lower also even at the most moderate of quantities versus 13.56 MHz and 125 KHz, there continues to be much debate as to whether the industry can deliver a sub 10 cent Tag. As of this writing, Tags in moderate quantities can be purchased for 50 cents and quantities into the millions can be purchased in the 30 cent range.

The primary application envisioned is supply chain tracking. The ability to identify hundreds of objects on a pallet through dock doors from manufacturing to warehouse to delivery at a retail level spells huge ROI in terms of wasted dollars in inventory, wasted sales due to lack of inventory, and the hands free/human free automation of identifying what is where.

There will undoubtedly be more applications in the future that 915 MHz can address, like airline baggage for example, there is one chief disadvantage to 915 MHz, the interference of liquids. A Tag that normally reads at 10′ will exhibit range of almost zero when placed in the shirt pocket of a user. Why, the liquid in the human body. Although a UHF spectrum, the same deficiencies as that of the microwave spectrum are present.

Active Tags at 433 MHz and 2.45 GHz:

Active Tags possess a battery thus powering a Tag with greater energy and signal strength and achieving greater distances. Tag costs are higher, $20 to $70, primarily due to the additional discrete electronic components necessary and the low quantity of Tags demanded by applications. Typical applications include:

  • Highway toll Tags.
  • Identification of private vehicle fleets in/out of a yard or facility.
  • Asset tracking.

Read ranges are typically 30′, however custom systems can read from hundreds of feet up to 1 mile, although these types of systems are not commercially marketed.

Having a battery, Tags do possess a finite life, 5 years typical.

Metal poses only a nominal interference factor.