Active RFID System Frequencies

Active RFID System Frequencies

Active RFID System Frequencies
Active RFID tags have a battery in them and are therefore more capable in terms of range and data handling.
 
Selecting an optimal radio frequency for operation of an active RFID system requires consideration of several factors, including technical performance, regulatory issues, and co-existence with other technologies. There is a broad range of suitable radio frequencies against these parameters. Of these 433 MHz is the optimal frequency for global use of active RFID in crowded, multi-tag environments at present. Around 433 MHz, the wavelength is approximately a meter, enabling signals to diffract around the vehicles, intermodal containers, and other large obstructions that are of interest where most long range tags are used. This contrasts with passive RFID, which is not used at 433 MHz because its range is inadequate at that frequency.
 
However, where there are few obstructions, UHF may be used with active tags and a range of 30 meters can still be achieved. For example, in the specialist situation of very high-speed reading of rail or road vehicles (eg non-stop tolling), UHF or 2.45 GHz are preferable provided there are few obstructions. Today, such tags only use modest data such as 24 bits (read-only) because they are in closed systems. Read-write versions keep a duplicate record of transactions using a few kilobits.