Miniaturization of a folded, inverted-F antenna for container RFID tag applications

Electrically small, low profile antennas have been designed for an active RFID system used for metallic container applications. A folded inverted-F antenna was first devised with a low profile characteristic and good impedance matching. For miniaturization of the antenna, triangular and C-shaped meanders were applied into long horizontal segments of the antenna while maintaining a 20mm height from ground plane. As a result, the triangular meander antenna was decreased in length to 42mm (0.06lambda) in horizontal segment. To reduce the antenna size even more, a C-shaped meander shape was employed, and, as a result, the diameter of the antenna was 34mm (0.049lambda). Measured results of the radiation pattern showed conical beam pattern. The designed antennas can be used for an active RFID system due to their small size and conical beam pattern.