The effect of feed position on the performance of a broadband reflectarray

The effect of changing the feed position on performance of a broadband reflectarray is investigated in this paper. An offset-fed broadband reflectarray is designed based on a unit-cell with wideband properties in X-Ku band. The proposed cell element consists of three concentric rectangular loops on a two-layer structure. The dimensions of the cell element have been optimized to achieve linear phase-shift range in the operation band. A Ku-band square reflectarray of 30 cm × 30 cm dimensions was designed and simulated in HFSS. The reflectarray is excited with a plane wave and the nearfield is calculated on several lines passing through the assumed feed locations and the operation bandwidth is estimated accordingly. Considering three different feed positions the reflectarray is excited using a horn antenna in CST, and the simulated results confirm the computed near-filed calculations.