Design of a Wideband Single-Layer Reflectarray Antenna Using Slotted Rectangular Patch With Concave Arms

A novel single-layer slotted rectangular patch with concave arms is proposed for wideband reflectarrays. The broadband characteristic is realized by combining both bandwidth enhancement techniques, i.e. using multi-resonant element and slotted rectangular patch element. By placing a pair of concave arms beside the slotted rectangular patch, additional resonance is introduced for an improved phase range and linearity. The element is optimized for a rather linear phase range covering 360°, resulting in a broadband behavior. Key geometrical parameters are studied to apprehend its working principle. Employing the novel unit cell, a reflectarray with 25° offset-fed, and constituting 23×23 elements with 0.3λ element periodicity at 10 GHz, is simulated and measured. Good agreement is obtained between the simulation and the measurement. The proposed reflectarray features a wide measured 32% 1-dB gain bandwidth and a maximum aperture efficiency of 65%. Furthermore, the measured side-lobe and cross-polarization levels are 20 dB and 32 dB at 10 GHz, respectively.