Novel RFID tag antenna with stability to material

In this paper, we suggested a novel RFID tag antenna in UHF band based on a new concept that the tag should always attain good readability irrespective of material characteristics of object. To optimize antenna structure we used Friss transmission equation considered return loss, radiation efficiency and directivity corresponding material of objects. The optimal tag was fabricated and measured the readable performance in terms of material comparing with the tag with inductively coupled feed. The measurement results verify that the proposed tag can be read stably on most of objects with various dielectric constants.