LAUSR

This paper presents the crescent-shaped slot antenna loading of a circular patch that greatly enhances a 3 dB axial-ratio (AR) bandwidth. A bent feeding line was introduced and attached to a 50- Ω microstrip feed line to achieve circular polarization operation. By loading the circular patch into a crescent-shaped slot at a proper position, the 3 dB AR bandwidth is considerably broadened. An antenna prototype with overall dimensions of 50.8 × 50.8 × 0.5 mm 3 is experimentally demonstrated. Measurement results of the fabricated antenna showed a wide −10 dB reflection bandwidth of 92.33% (1.79–4.86 GHz) and a broad 3 dB AR bandwidth of 84.40% (1.89–4.65 GHz). The measured peak gain of the antenna was approximately 4.09 dBic at 2.9 GHz. Good agreement was also achieved between measurement and simulation results.