Optimized Limited Size Printed Bowtie Antenna for UHF RFID Readers

Abstract A novel design of a printed bowtie antenna without a ground plane and with size below a quarter wavelength for RFID readers is presented. Due to the lack of a ground plane, the designed antenna has omnidirectional characteristics and is insensitive to small permittivity deviations. For matching purposes without introducing gain distortion, a shorting strip connecting the radiating arms and four triangular shaped extensions of the radiating arms are added to the antenna design. Measurements show that operation in the 915 MHz band is met with a bandwidth of 13% (S11 < -10 dB) and gain around 2 dBi, while presenting an omnidirectional radiation pattern. Also, the proposed antenna design can be easily modified to operate at neighboring frequency bands.