A sub-wavelength reflectarray element based on double square rings loaded with meander lines

A sub-wavelength phase-shifter element is presented for a single-layer reflectarray design at 10 GHz. The element has a size of around a fifth of a wavelength and consists of double concentric square rings loaded with meander lines. By changing the length of the meander line from 0 to 1mm, a 340 degree phase variation range can be achieved, which is much greater than many reported sub-wavelength reflectarray elements. In addition, the slope of the phase response remains almost constant at 9 GHz and 11 GHz, implying the proposed element has broadband properties. A WR 90 waveguide is used to measure the reflection phase of the elements and good agreement between the simulated and measured results are obtained.