The Design of Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) Reader Antenna

Abstract

This paper presents the design of ultra-high frequency (UHF) radio frequency identification (RFID) reader antenna using low dielectric constant of microwave substrate. An RFID reader antenna emits electromagnetic signals to the microchip in the tag, and the microchip will be energized by modulating the wave and returns to the reader antenna. The process of wave emitting is known as backscattering due to the presence of tag been detected by the reader. High-dielectric constant substrate, for example flame-retardant-4 (FR4) which is commonly used for microstrip patch antenna, is high in dielectric constant and dielectric loss. Thus, this will lead to low gain and directivity properties of the antenna. To overcome this matter, low-dielectric constant substrate which is Taconic TLY-5 was proposed to be utilized for microstrip patch antenna design. The TLY-5 microstrip substrate thickness used is 1.6 mm, dielectric constant of 2.2, and loss tangent of 0.019. A high-conductivity metal which is typically a conductive copper is been used for the two layers of dielectric substrate, the top radiating patch layer and bottom ground layer where the copper thickness is 0.035 mm. Microstrip feed line is used for this UHF RFID reader antenna. The width of the feed line was tuned to obtain impedance matching of 50 Ω. The proposed antenna which is fork-shaped patch antenna was simulated using Computer Simulation Technology (CST) and Microwave Studio software at resonant frequency of 910 MHz with the outcome results of 7.985 dB gain and −11.11 dB return loss. Nevertheless, the typical value obtained for VSWR is less than 2.