Small size circularly polarized patch antenna for 2.4 GHz WLAN applications

A very small size 19 mm × 19 mm × 0.4 mm circularly polarized (CP) square ring patch antenna for 2.4 GHz WLAN (Wireless Local Area Network) applications is proposed. To excite CP radiation for this square ring patch antenna, a meandered structure loaded with a 100 Ω resistor chip is used as the feeding mechanism of this antenna. Furthermore, an open-ended L-shaped strip is also extended from this meandered feeding structure, so that good CP can be achieved at 2.4 GHz band. The measured 10-dB return loss of the proposed CP antenna was 9.42% (2285-2511 MHz), and its corresponding 3-dB axial bandwidth (AR) was 2.86% (2410-2480 MHz).