Non-resonant conductor reflectarray element for linear reflection phase

A reflectarray element using a conductor cell with variable height is proposed. It is found that the reflection phase can be tuned by adjusting the height of the conductor cells arranged on the spatially discretised reflector plane. A complete linearised reflection phase thus can be achieved when the proposed conductor cell is used as a unit element. A millimetre-wave antenna has been designed using the proposed method and it shows 50% aperture efficiency with a half-wavelength cell height variation.