Wideband Solar-Cell Integrated Yagi-Uda Antenna

Abstract

A wideband ultra-low-profile Yagi-Uda type of solar-cell integrated antenna is presented. The proposed antenna consists of a driver, reflector, and director, and is also designed to function as a solar cell. An ultra-low-profile copper indium gallium selenide (CIGS) based solar cell is used as a driver, and a slit is cut from it to make a built-in solar-cell antenna. A CIGS solar cell-based reflector and director are added to increase the impedance bandwidth and gain of the proposed antenna. A narrow slit is used, and the spacings between the reflector, driver, and director are minimized to increase the solar-cell form factor. A coaxial-to-microstrip line transition type feeding structure is used to excite the antenna, which is printed under the second substrate. Three RF decoupler circuits are designed for the driver, reflector, and director to separate the antenna functionality from the solar cell. The antenna has overall dimensions of $0.71~\lambda _{o} \times 0.61~\lambda _{o} \times 0.006~\lambda _{o}$ at 3.2 GHz. Furthermore, the proposed antenna design possesses a wide measured impedance bandwidth of 56.7%, radiation efficiency of higher than 90%, a maximum measured gain of 5.67 dBi within the impedance bandwidth, and a solar-cell form factor of 89.7% with no optical blockage.