GPS patch antenna with photovoltaic solar cells for vehicular applications

This paper describes the application of photovoltaic (PV) solar cells in planar antenna structures. The radiating patch element of a planar antenna is replaced by a solar cell. The original feature of a solar cell (DC current generation) remains, but additionally the cell is now able to receive and transmit electromagnetic waves. Both single solar cells as well as solar cell arrays can be used as antennas. However, the DC connection of the solar cells must be considered. By means of an elaborated series connection of the solar cells a harmful influence on the antenna properties may be avoided. Besides a general technical description, a solar-cell antenna for GPS applications is presented in detail. As a demonstrator, an aperture coupled patch antenna has been realised, which is suited for integration in vehicular glass roofs. The solar cell antenna is manufactured with commonly used production methods for solar modules. It turned out that some of the used materials degrade the antenna properties. Nevertheless, the comparison of measured and simulated antenna properties shows a good agreement, and the antenna works well with commercial GPS receivers. The DC voltage of the solar cells is about 18 V. Thus support of the car battery and the power supply is possible, which enables new applications like permanent cabin ventilation.