A novel microstrip rotating cell for CP-reflectarray applications

This paper presents a new low-profile rotating element for circularly polarized microstrip reflectarray antennas. The proposed cell was first designed to operate in the X-band frequency range at 9.4 GHz, then the cell dimensions were reduced to shift the operating frequency up to 30 GHz. The element is printed on a thin substrate with ε_r = 2.2 and 0.254 mm thickness. Unlike most of the cp-reflectarray elements the ground sheet is directly attached to the down layer of the substrate and no foam is needed which in turn reduces the fabrication costs and facilitates the mounting of the cp-reflectarray antenna. A full wave simulation using CST-MWS was applied on the proposed element and farfield monitors were assigned to the simulation setup. The proposed element proved to maintain the sense of polarization of the incident circularly polarized plane wave upon reflection, having a cross-polarization component of -30 dB at 9.4 GHz and -20 dB at 30 GHz. Also, it showed an axial ratio of 0 dB at the line of sight θ=0^o at both frequencies and provides a 10.6% fractional bandwidth.