A Pattern Reconfigurable Antenna with Broadband Circular Polarization

In this paper, a simple pattern reconfigurable antenna with broadband circular polarization is proposed. The proposed antenna consists of four rectangular loops, a feeding network and four reflectors. Circular polarization is achieved by cutting two slots on opposite sides of the loops. By controlling the states of the four PIN diodes present in the feeding network, the proposed antenna can achieve four different pattern modes at the same frequency. Experiments show that the antenna has a bandwidth of 47.6% covering 1.73-2.81GHz for reflection coefficient (|S11|)<-10dB and a bandwidth of 55% covering 1.62-2.85GHz for axial ratio <3dB. The average gain is 8.5dBi and the radiation patterns are stable.