Low frequency range includes frequencies from 30 to 300 KHz but only 125 KHz and 134 KHz (actually, 134.2 KHz) are used for RFID. This range has been in use for RFID tags for animal tracking since 1979 and is the most mature range in use. It is available for RFID use all over the world. The tags in this range are generally called LF tags. They use near-field inductive coupling to obtain power and to communicate with the interrogator. The LF tags are passive tags (no battery and transmitter on the tag) and have a short read range of a few inches. They have the lowest data transfer rate among all the RFID frequencies and usually store a small amount of data. The LF tags have no or limited anti-collision capabilities; therefore, reading multiple tags simultaneously in the IZ is impossible or very difficult. The tag antennas are usually made of a copper coil with hundreds of turns wound around a ferrous core. They are expensive to manufacture, and tags using them are thicker than others at higher frequencies. The LF tags can be easily read while attached to objects containing water, animal tissues, metal, wood, and liquids.
LF tags have the largest installed base. They are used in access control, asset tracking, animal identification, automotive control, as vehicle immobilizers, healthcare, and various point-of-sale applications (such as Mobil/Exxon SpeedPass). The automotive industry is the largest user of LF tags. For example, in an automobile vehicle immobilizer system, an LF tag is embedded inside the ignition key. When that key is used to start the car, an RFID interrogator placed around the key slot reads the tag ID. If the tag ID is correct, the car can be started. If the ID is incorrect or no tag is found, the car cannot be started.