A Koch-Shaped Log-Periodic Dipole Array (LPDA) Antenna for Universal Ultra-High-Frequency (UHF) Radio Frequency Identification (RFID) Handheld Reader

In this communication, we propose a printed log-periodic dipole array (LPDA) antenna covering the universal ultra-high-frequency (UHF) radio frequency identification (RFID) band of operation. Koch-shaped dipoles together with closely-coupled parasitic elements as directors were utilized for compactness in size and improvement in front-to-back ratio (F/B ratio). The experimental results demonstrate that the proposed antenna features good impedance match, moderate gain, better than 80% total radiation efficiency and excellent front-to-back ratio over the universal UHF RFID band from 840 MHz to 960 MHz. The antenna is well suitable for applications in RFID handheld readers.