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.

A triple-band CP rectenna for ambient RF energy harvesting is presented in this paper. A simple broadband CP slot antenna has been proposed with the bandwidth of 51.1% operating from 1.53 to 2.58GHz, which can cover GSM-1800, UMTS-2100 and 2.45GHz WLAN bands. Accordingly, a triple-band rectifying circuit is designed to convert RF energy in the above bands, with the maximum RF-DC conversion efficiency of 42.5% at a relatively low input power of -5dBm. Additionally, the rectenna achieves the maximum conversion efficiency of 12.7% in the laboratory measurements. The measured results show a good performance in the laboratory measurements.