A Dual-band Beam-Scanning Reflectarray with Circular Polarization for SatCom millimeter-wave Applications

This study presents a dual-band reflectarray (RA) with circular polarization based on Liquid Crystal (LC) technology. An LC Unit Cell (UC) is proposed which consists of 3 High-Band (HB) elements that are interleaved around a Low-Band (LB) element. The element consists of a cross-patch on top of a slot-loaded square patch. The LC is used as a substrate between the cross and square patch. By applying a variable voltage between the two patches, the resonant frequency of each element changes and provides the required phase difference. A $20\times 20$ element RA is simulated with 400 LB elements and 1200 HB elements. The RA 3-dB gain and Axial Ratio (AR) overlapped bandwidth at 19.5 GHz and 28.5 GHz are 8%, and 9.5%, respectively. The beam-scanning range at each frequency band is $\pm 45^{\circ}$. The proposed design can be a good candidate for the satellite constellations at the millimeter wave.