Low-Profile Meandered Patch Antennas for RFID Tags Mountable on Metallic Objects

This letter presents novel meandered patch antennas that are designed for ultrahigh frequency (UHF) band radio frequency identification (RFID) tags mountable on metallic objects. The antenna has a low-profile structure (0.8 mm thick). Meandering a long patch into several half-wavelength radiating elements makes the surface currents of all radiating elements in phase, thus achieving an enhanced antenna gain and a good reading range performance. In addition, the proposed antennas mounted on a 400 × 400 mm
²
metal plate are studied. Little effect of the metal-plate size on the reading range is obtained.