Small Proximity Coupled Ceramic Patch Antenna for UHF RFID Tag Mountable on Metallic Objects

A very small patch type RFID tag antenna (UHF band) using ceramic material and proximity coupled feeding structure mountable on metallic objects is presented. The proposed tag size is 25×25×3 mm. Both of the radiating part and the feeding part of the proposed antenna is located in the same plate for easy implementation. The resistive and reactive components of the input impedance of the antenna can be easily matched to the tag chip impedance from the size of the feed loop and the distance between feed loop and radiating patch. The antenna satisfactorily operates on metal plates, so it is applicable in many applications. The proposed design is verified by simulation and measurements which show good agreement.