Effects of metallic plate size on the performance of microstrip patch-type tag antennas for passive RFID

Metallic objects are challenging for passive ultra high frequency (UHF) spectrum radio frequency identification (RFID) systems due to the effects of conductive materials on tag antenna performance. In this letter, we analyze the effects of metallic plate size on the performance of microstrip patch-type tag antennas. Microstrip patch antennas with regular ground plane and electromagnetic band gap (EBG) ground plane are studied attached to two differently sized metallic plates. Analysis is based on finite element method (FEM) simulations and practical read-range measurements.