An offset-fed X-band reflectarray antenna using a modified element rotation technique

An X-band circularly polarized reflectarray antenna with an offset feed is designed, fabricated, and measured. The proposed design features the use of split square ring elements with a modified element rotation technique for phase compensation, which allows the rotation of the slot instead of the element itself. This is crucial in single-layer multiband reflectarray antenna designs where it is desired to minimize the effectively occupied area by individual elements. A design flow chart of the reflectarray antenna is summarized, and the element/system design procedure is presented in details. A reflectarray prototype was measured in a near field measurement system, which operates at 8.4 GHz with a gain of 30.4 dB and an aperture efficiency of 53.7%. Both the axial ratio bandwidth (AR < 3 dB) and the 3 dB gain bandwidth are 6%.