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Active vs Passive RFID


Active RFID Reader 433 MHzThere are three basic types of RFID Systems at the time of this writing. The categorization and naming of these systems is based upon the design and operation of the tags (Active tags=Active System, etc). All systems rely upon a radio receiver and a radio transmitter.   

The first system type is Active RFID where the RFID Reader (radio receiver) is passive and "listens" for radio transmissions from Active RFID tags. Active RFID tags are comprised of a radio transmitter and a power source, which is usually a miniature battery. Because Active RFID Tags include a radio transmitter and power source, they are capable of transmitting over a greater range than other systems. Active RFID tags can hold a lot of stored information that can be transmitted and are typically more expensive. Active RFID Tags are best suited for long range monitoring of high dollar assets and personnel or when real time location of assets is desired. Active RFID tags are more likely to be detected on fast moving assets. Many active RFID Tags are dual purpose transmit tag data for serial use and for wiegand use so that the same tag can be used for data collection and with card access systems. Active RFID tags can also transmit motion data, tamper data, and tag age. Some models of Active RFID tags are capable of transmitting telemetry data such as temperature and humidity. Wavetrend manufactures a kinetic tag that transmits accelerometer data. In order to preserve battery life and conform to FCC requirements, Active RFID tags sold in the USA are not always transmitting, rather they transmit a beacon at a rate of ~15 seconds when at rest, and much faster when the integral motion sensor has detected movement.
Passive RFID TagThe second system type is Passive RFID, where the radio component is a transceiver that transmits RF energy (usually 2.4 GHz microwave) and Passive Tags that are excited by the energy of the transmitter and  then respond with authentication back to the receiver. It is the energy from the transceiver that powers the tag. Most wiegand card access systems are actually Passive RFID systems. When an access card is placed close to the card reader, the energy from the reader excites the tag and the tags energy is then detected by the reader. Passive tags hold very little information other than the tag ID and must be near the transceiver in order to be detected. Because the tags do not contain electronics, or a power source they are considered to be "asleep" until they are presented to the transceiver. Passive RFID tags are typically inexpensive and are used for inventory management of lower cost items or near field use. Passive tags can be printed on labels and are generally considered for one time use, or disposable. They can also be embedded in more durable plastic for card access use or embedded in pets for identification purposes. In order for passive RFID tags to be detected at greater distances, the energy level of the transceiver needs to be increased and/or the antenna surface area needs to be increased. 
The third and least common system is called Battery Assisted Passive RFID, which is very similar to Passive RFID except that the tag has a integral power source that is activated only when the Radio signal generated by the transceiver is detected by the tag; which then transmits specifics of the tag back to the transceiver. Battery Assisted Passive RFID tags are more expensive than passive RFID Tags and can rival the cost of Active RFID Tags. Battery Assisted Passive are considered to be "asleep" until activated by the transceiver.

Our Active RFID Designs and Systems

Active RFID TagFor most of our designs, Active RFID offers the best performance for tracking high dollar assets and personnel as well as locating assets with near real time tag data. Because active RFID tags are always transmitting, and not "asleep" like passive tags, not only is it possible to determine when a tag has entered the reader's range, but it is possible to determine when a tag has left the reader's range. Our RFID systems can be as simple as as one or two readers, but the readers can be daisy chained to build arrays of dozens of readers and zones, so that assets can be tracked as they move throughout a facility. Because our systems are based upon long range Active RFID, they are excellent for handsfree operation of security gates at commercial facilities, country clubs and gated communities. With our RFID Track Integration for iOS, assets location can be determined in the palm of your hand using an iPod Touch, iPhone or iPad. Active RFID Tags can be mounted with adhesive, lanyard, or ID Badge clips. Bolt on Models are also available. We offer a variety of tags for personnel, vehicles, heavy equipment, electronics, and pets. We offer a variety of special purpose active RFID tags for industrial applications, wet locations and hazardous locations and tags with telemetry capabilities for temperature and/or humidity.

Uses for Active RFID Tags

  • Hands free Access Control
  • Mustering during a building evacuation
  • Vehicle Detection and Gate Operation
  • Equipment Tracking
  • Personnel Location
  • Visitor Registration and Tracking
  • Evacuation Systems
  • Animal Identification
  • Heavy Equipment Tracking
  • Asset Management
  • Medical Equipment - Frequently Moved Items
  • Sports
  • Transportation
  • Product and Assembly Tracking

Uses for Passive RFID Tags

  • Inventory Managagment
  • Tracking of goods
  • Library Management - Books and Media
  • Near-field Card Access
  • Medical Inventory Management