Gain enhancement for low cost planar reflectarray antenna using hybrid elements

Abstract

By using a hybrid configuration of reflective elements of at least two different types, the gain of a planar reflectarray antenna is successfully enhanced. According to the calculated phase‐shift distribution, the reflecting surface is covered mainly by traditional low‐loss element such as square patches (SPs) in the first. Then the blank cells, of which the required phase‐shift exceed the operational range of the SP, are covered by other elements having large phase‐shift, for example, the three‐ring patches. As a result, the antenna efficiency is kept in a high level because the low loss elements are in majority. Meanwhile, the main beam efficiency is kept high because the sidelobe level is suppressed by large phase‐shift elements. For verification, an experimental array is fabricated on an inversely suspended, low cost FR4 substrate. The simulated result shows that the sample antenna is advanced in high gain and low sidelobe level, comparing with its traditional counterparts with only one type reflectarray elements. The measured result agrees well with the simulations, which show the gain of the antenna is higher than 26 dB, while the sidelobe suppression is lower than −19 dB. The aperture efficiency reaches about 47.04% at 14.0 GHz, which achieves the performance of high‐cost reflectarray antenna.