A Dual Band Circularly Polarized Planar Monopole Antenna for WLAN/Wi Fi Applications
This letter presents a dual band circularly polarized planar monopole antenna. The antenna consists of a radiator, a ground plane, and a microstrip line. The radiator is composed of a "C" shaped strip and an "L" shaped strip. The "C" shaped strip is mainly used for the higher band, and the "L" shaped strip for the lower band. The overall dimension of the prototype is only 40 x47 x1.5 mm3. The proposed antenna has been built and tested. Its measured 10 dB impedance bandwidths are 380 MHz (2.32 2.70 GHz) in the lower band and 1240 MHz (4.76 6 GHz) in the higher band. Its measured 3 dB axial ratio (AR) bandwidths in the broadside direction are 180 MHz (2.39 2.57 GHz) in the lower band and 870 MHz (5.13 6 GHz) in the higher band. The overlapped impedance and AR bandwidths can fully cover all the 2.4/5.2/5.8 GHz WLAN bands and all the 2.4/5.5 GHz Wi Fi bands. The patterns have the characteristic of bidirectional radiation, and the gains are stable in both bands.
IEEE Antennas and Wireless Propagation Letters