Dual-band circularly polarized slotted monopole antenna

This paper presents a dual-band circularly polarized slotted monopole antenna. This antenna is fed by a 50 O microstrip line. The measured results demonstrate that the slotted monopole antenna has a return loss <; 10dB, an axial ratio (AR) <; 3dB, and 6 % circular polarization bandwidth with respect to the center frequency at 2.4 GHz, and 1.7 % circular polarization bandwidth with respect to the center frequency at 5.25 GHz. This antenna can excite a left-hand circular polarization (LHCP) at 2.4 GHz, and right-hand circular polarization at 5.25 GHz. At the center frequency of 2.4 GHz and 5.2 GHz, the measured impedance bandwidth are about 190 MHz and 180 MHz respectively.