RFID products fall into two basic categories: Passive and Active. Passive tags do not have batteries and have indefinite life expectancies. Active Tags are powered by batteries and either have to be recharged, have their batteries replaced or be disposed of when the batteries fail.
Various Types of Antennas (above)
RFID products are then broken up into different frequencies. Tags and Antennas are tuned or matched much the same way as a radio is tuned to a frequency to receive different channels. These frequencies are grouped into Four basic ranges: Low Frequency, High Frequency, Very High Frequency and Ultra-High Frequencies.
Each frequency range has its advantages and disadvantages. Europe use 868 MHz. for its UHF applications while the US uses 915 MHz. for its UHF applications. Japan does not allow the use of the UHF frequency for RFID applications. Low Frequency tags (LF) are less costly to manufacturer than Ultra High Frequency (UHF) tags. UHF tags offer better read/write range and can transfer data faster then other tags. HF tags work best at close range but are more effective at penetrating non-metal objects especially objects with high water content.
Various Types of Tags (above)
Once a frequency range is determined, then it is time to choose an antenna that best fits the application. Antennas come in all sorts of sizes and shapes. The size of the antenna determines the range of the application. Large antennas used with Active Tags can have a range of 100 feet or more. Large antennas used with Passive Tags generally have a range of 10 feet of less. There are dock door antennas (some times called Portals) that allow a forklift driver to drive between two antennas. Information can be collected from the tags without the forklift driver having to stop. There are antennas that mount between rollers on conveyors for reading/writing from below. While other antennas are available that mount to the side of or above the conveyors. Handheld Reader/Writers are available as well.
Controllers are available to communicate with most Networks (Ethernet, DeviceNet, ProFibus, etc). They typically have serial ports for programming and data transfer. Controllers are usually shipped with programming software to set-up and customize the application. Controllers typically operate on 120VAC or 24VDC.