What is the relationship between frequency and tag/antenna distance?
Passive high-frequency (HF, typically 13 MHz) and low-frequency (LF, around 125 kHz) systems typically exhibit a read range of less than 3 feet. With HF and LF tag systems, the size of a tag (and hence area of antenna) will have a significant impact on read range. Some applications limit the read range to around 6 to 8 inches. Some newer technologies (UHF systems) do have a longer read range that can be 20 to 25 feet, but these systems are intended for pallets and shipping crates. Read range depends on many factors, but the size of the transponder’s antenna, the size of the reader’s antenna, and its output power are the main factors to consider. With battery-less transponders, long read range and small size are mutually exclusive.