Abstract
A small-size printed loop antenna operated at its half guided wavelength (λg /2) mode as the fundamental resonant mode for achieving operation in Taiwan RFID UHF band is presented. The proposed antenna consists of a half guided wavelength loop antenna, inter-digital coupling section and a small U-shaped strip inductance structure. The proposed antenna has a simple structure of comprising shorting via of length about 118 mm to cover the Taiwan RFID UHF bands. Further, the antenna has a simple planar structure and occupies a small area of 30 × 40 mm2 on the system circuit board of the metallic object. This proposed antenna with good matched impedance, compact size, and measured maximum reading range in free-space is about 7.2 m, which can be suitable for RFID applications. Details of the proposed loop are discussed in this paper.