An X-Band Reflectarray With Novel Elements and Enhanced Bandwidth

A novel single-layer reflectarray element with an I-shaped dipole encompassed by a circular ring, showing smooth phase-frequency response, is proposed in this letter. Based on this element, an optimization method is adopted to match the desired phase delays at two edge frequencies so as to get fixed phase difference between two adjacent elements in the optimized band. A low-profile X-band 6 $,\times,$ 10-element reflectarray with a scattering angle of 30 $^{\circ}$ for normal incidence of plane waves is designed and fabricated. Simulations and measurements show that a bandwidth of 22.3% for 3 dB directivity dropping and 15.2% for ${-}$ 10 dB sidelobe level (SLL) can be achieved.