Small EBG Decoupling Structure for High Isolation between Two RFID Tags

In this paper, we show a new scheme to tackle the problems of high electromagnetic-coupling, poor impedance-matching and degraded radiation-characteristics of two RFID tag antenna, when they are located with an extremely short distance. As giving it a variety of tries such as periodic EBG-type structures and notch-making stubs, we can get an optimal device to lower the electromagnetic coupling and to match the input impedance of both of the tag antennas. Even for a UHF-band, the device is very thin less than 1 mm unlike other isolation-enhancers which are thick or multi-layered. The dips in the S
11
and S
21
–curves are generated at the target frequency, which means excellent impedance match and lowered interference for the two tag dipole-antennas. This is helpful to higher thruput in RFID.