readrange

Readrange refers to the maximum distance over which a reader can reliably detect and decode a tag’s response in an RFID system. It is influenced by frequency band, tag type, antenna design, and environmental conditions, and it varies across different technologies and deployments.

In RFID, readrange depends on whether tags are passive or active. Passive tags rely on energy harvested from the reader’s signal, so their range is typically shorter than that of active tags, which have their own power source. Different frequency ranges produce different ranges: low-frequency (LF, around 125–134 kHz) systems usually read within a few centimeters; high-frequency (HF, 13.56 MHz) systems commonly reach several centimeters to about a meter with stronger hardware; ultra-high-frequency (UHF, about 860–960 MHz) systems commonly span from about 1 to 10 meters, and sometimes farther with specialized equipment. Active tags can extend readrange to tens or hundreds of meters.

Key factors affecting readrange include transmitted power and antenna gain, tag antenna design and orientation, polarization, and the presence of interfering materials such as metal or liquids. Environmental conditions, regulatory limits on transmitted power, multipath effects, and reader/tags’ compatibility also play significant roles.

Measurement and specification practices vary: manufacturers publish readrange under defined test conditions, which may not reflect field performance. Real-world readrange is affected by tag placement, orientation, crowding, and nearby objects. To optimize range, systems may use larger or higher-gain antennas, carefully position tags, select appropriate frequency bands, and consider the environment and regulatory constraints.

See also: RFID, passive tag, active tag, ISO/IEC 18000, EPC Gen 2.