First-Order Minkowski Fractal Circularly Polarized Slot Loop Antenna With Simple Feeding Network for Uhf Rfid Reader

Abstract

Abstract-A circularly polarized (CP) antenna with simple feeding network for ultra-high-frequency (UHF) radio-frequency identification (RFID) reader application is presented in this letter. The proposed antenna consists of a slot loop etched on the ground and a simple feeding network using bended microstrip lines. And the two parts of the antenna are printed on either sides of a thin substrate, thus a low-profile antenna is obtained. The slot loop is meandered based on the first-order Minkowski fractal technique for antenna size reduction. To generate circularly polarized radiation, two branches of the feeding network are designed to be orthorhombic with 90 • phase difference. The antenna is simulated and practically fabricated with a compact size of 80 × 80 × 1.6 mm 3 . The 10-dB impedance bandwidth and 3-dB axial-ratio (AR) bandwidth are measured to be 50 MHz (0.896-0.946 GHz) and 12 MHz (0.916-0.928 GHz), respectively. The measured peak gain exhibits stable value of 3 dBi over the impedance bandwidth. Furthermore, a wide 3-dB beamwidth of 120 • is achieved for the proposed antenna. Based on the above, this antenna is well suited for applications in UHF RFID handheld readers.

High Gain Flexible CPW Fed Fractal Antenna for Bluetooth/Wlan/Wpan/Wimax Applications

“…This is due to the capacitive effect created by the slot, and it helps in achieving dual frequency bands. Minkowski type fractal geometry [22] is introduced which helps in improving the return loss and impedance bandwidth. C shaped branches protruding on both sides of the center patch help in achieving the proposed frequency bands of operation.…”

A Miniaturized Multi-layer Microstrip Antenna for Linear Wireless Sensor Network Monitoring Systems

“…Several methods have been considered for reducing the resonant frequency of microstrip antennas, as well as size reduction. Slot-loaded patch antennas have proved to be satisfactory in miniaturizing microstrip antennas, and increasing the electrical length of the antenna, thereby producing multiple resonant bands, as well as the reduction of the overall size [13][14][15]. Also, embedded slots can increase the current path and achieve additional impedance matches.…”

A coplanar waveguide fed tilted fractal inspired slot antenna for wideband circular polarization

“…In recent past, fractal inspired structures are also used for the generation of circular polarization . In References 11 and 12, Koch fractal structure is used for the circular polarization.…”

“…In Reference , asymmetrical fractal boundary microstrip antenna and, in Reference , a semi‐fractal grounded ring slot antenna are used for the generation of circular polarization. In Reference , first‐order Minkowiski fractal slot loop antenna and, in Reference , a fractal slot geometry fed by an F‐shaped microstrip line are studied for circular polarization.…”