| Abstract: | In this article, a new 2 × 2 circular microstrip antenna array with air dielectric layer for ambient RF energy harvesting has been proposed. Two pairs of arc‐shaped slots located close to the boundary of the circular microstrip patch have been designed for achieving dual‐band response and extending the frequency bandwidth. The antenna has a frequency bandwidth from 1.85 to 1.93 GHz and from 2.0 to 2.1 GHz which can cover GSM‐1800 and UMTS‐2100 bands. At the frequency of 1.89 and 2.05 GHz, the measured gain is 5.3 and 6.6 dBi, respectively, and high gain of 3.8‐9.3 dBi has been achieved over the whole band. Also, a broadband rectifier that can cover all the bandwidths of the antenna array is designed for the rectenna, which has the maximum rectifying efficiency of 53.6%. Finally, a cube device formed of four antenna and four rectifiers is designed to harvest RF energy, whose maximum output DC voltage is 2.3 V and the maximum output power is 4 mW that can drive four LEDs and an electronic watch. |
