A Coupled-Feed Monopole Antenna for UHF RFID Reader Application

A monopole antenna working in the ultra-high frequency band (UHF) at 915 MHz is proposed. To achieve good excitation at UHF RFID band, two slits are loaded into the radiating element of the antenna, while this antenna is standing vertically on a small ground. To improve the operating bandwidth of this monopole antenna, the coupled-feed technique is applied. Besides demonstrating a small planar size of 80×64 mm² the proposed antenna monopole UHF RFID antenna has also exhibited 10-dB impedance bandwidth of 3.6% (897-930 MHz) and realized gain of >0.5 dBi.