Microstrip-line-fed circularly-polarized circular slot antenna with a spur slot

A new Microstrip-line-fed circularly-polarized circular slot antenna with a spur slot is presented. The proposed circularly-polarized (CP) operation can be achieved simply by embedding the spur slot along the circumference of circular slot. From the experimental results, the 3-dB axial-ratio bandwidth can reach as large as 105 MHz (4.3% relative to the centre frequency of 2447.5 MHz) for the application as a 2.45-GHz RFID reader.