The purpose of this paper is the design of a novel single layer reflectarray antenna in X-band, which can electronically steer the antenna beam and change its polarization. Each antenna element includes a circular patch and rings around it, equipped with two varactor diodes, which are positioned perpendicular together to create a circular polarization. First, using these elements, a circular polarized active electromagnetic band-gap (EBG) reflector is implemented. Then, a special feed is placed in a proper distance with respect to EBG reflector and a circular polarized reflectarray antenna is designed, which has capability of switching electronically between right- and left-handed circular polarizations. An electronic active board is designed and fabricated to provide the biasing voltages, control signals, and indicators. The elements of the reflectarray are designed and arranged in such a way that the varactor diodes can be biased independently. Consequently, a 3D beam is created, which can steer up to ±40o. For evaluating the antenna performance, the radiation patterns and the axial ratio of the antenna are determined at the operational frequency of 11.4 GHz. It is illustrated that, increasing the steering angle in θ direction decreases the directivity and the gain of the reflectarray antenna.

中文翻译：

---

具有电子可控波束和可互换极化的圆极化反射阵列天线

本文的目的是设计一种新型 X 波段单层反射阵列天线，该天线可以电子控制天线波束并改变其极化。每个天线元件包括一个圆形贴片和围绕它的环，配备两个变容二极管，它们垂直放置在一起以产生圆极化。首先，使用这些元件，实现了圆极化有源电磁带隙 (EBG) 反射器。然后，在相对于EBG反射器的适当距离处放置一个特殊的馈源，并设计了一个圆极化反射阵列天线，该天线具有在右旋和左旋圆极化之间进行电子切换的能力。设计和制造了一个电子有源板，以提供偏置电压、控制信号和指示器。反射阵列的元件的设计和排列方式使得变容二极管可以独立偏置。因此，创建了一个 3D 光束，它可以控制高达 ±40○. 为了评估天线性能，天线的辐射方向图和轴比在 11.4 GHz 的工作频率下确定。可以看出，增大转向角θ方向会降低反射阵列天线的方向性和增益。