Dual-ID Headgear UHF RFID Tag with Broadside and End-Fire Patterns based on Quasi-Yagi Antenna

Abstract

We present a wearable quasi-Yagi antenna on a periodic surface for a dual-ID passive UHF RFID tag embedded in headgear. The antenna produces a near end-fire radiation pattern directed towards the user's line of sight with the directivity of 4 dBi. Moreover, it integrates another tag by utilizing the Yagi antenna's reflector as a second dipole tag antenna with broadside radiation directed upwards from the user. Hence, in one platform, we obtain a dual-ID tag with near end-fire and broadside patterns for the two tag IDs. The former is achieved by inserting a periodic surface made up of a 2-by-2 grid of square loops in between the antenna and the body. This enhances the launching of surface waves for achieving the end-fire radiation and suppresses the undesired electromagnetic antenna-body interaction.