Low-Profile Wideband Reflectarray by Novel Elements With Linear Phase Response

This letter presents a reflectarray antenna composed of a combination of concentric open rings and an I-shaped dipole on a conductor-backed substrate. Two classes of elements with different variable dimensional parameters are introduced to realize linear phase-frequency characteristic in a wide frequency band and a phase range of over 360^° . It is worth noting that the wideband performance is figured by the proposed reflectarray with a low profile of 0.065λ₀ ( λ₀ is the free-space wavelength at the center frequency), rather than thick substrate employed in common wideband designs. A prototype is fabricated and measured to verify the availability of the elements, and the measured results show good agreement with simulations.