Effects of metal plate to RFID tag antenna parameters

Design of a Wideband Inductively Coupled Loop Feed Patch Antenna for UHF RFID Tag

“…To further evaluate the performance of the antenna, the theoretical maximum read range of the antenna was calculated using Friis transmission equation (8) at three different operating frequencies as listed in Tab. 2 [3].…”

“…Although numerous works have been done in designing tag antenna, there are still many open issues that require further studies and research in order to truly exploit its potential. One of the issues is performance degradation of commonly used label typed dipole tag antenna [4][5][6] when placed on metal surface due to cancellation of tangential electric current at the boundary between the antenna and the metal surface [7], [8]. One of the many attempts to mitigate the problem is to separate the antenna and the metal surface by using a foam spacer to create constructive interference between the incoming and reflected signal.…”

Design and Development of a Compact Wideband C-Shaped Patch Antenna for UHF RFID Tag

“…Several works have been presented by Fang et al (2008) and Monti et al (2010) with the aims to miniaturize the size, increase the read range and improve the radiation characteristic of the antenna. However, it has been reported that these tag suffers performance degradation when attached to metallic objects (Ukkonen et al, 2005;Prothro et al, 2006;Ghannay et al, 2009). The cancellation of the incoming and reflected signal has caused a shift in operating frequency, degradation of impedance matching and distortion in radiation pattern which causes the reader not able to read the tag.…”

A planar wideband microstrip patch antenna for UHF RFID tag

“…However, there is limitation faced by this type of antenna which is serious performance degradation when mounted on metallic objects. This is due to current induced in the antenna is cancelled by the opposite image current induced in the metallic objects since at the surface of the perfect electric conductor (PEC), the tangential component of electric field cannot exist [8,9]. This scenario lead to changes in the antenna performances like shift in operating frequency thus leads to impedance mismatch, distorted radiation pattern and reduce gain.…”