By Jerry Banks and Les G. Thompson, co-authors of RFID Applied

The design of the antennas used by RFID tags and RFID readers is one of the most critical pieces in RFID infrastructure. This is because the antennas facilitate the communication between an RFID reader and a tag through free space. Both the reader and the tag utilize an antenna to transmit and receive data. In the case of passive RFID systems, the antennas have the added burden of being able to efficiently collect and radiate energy, respectively. Without well designed antennas there can be no efficient communication between the tags and readers, and, in the case of passive tags, there may not be enough energy to power the tag.