On the Selection of the Number of Bits to Control a Dynamic Digital MEMS Reflectarray

The benefit of low loss exhibited in utilizing MEMS variable capacitors in a reconfigurable reflectarray is undermined by the inconsistency of the fabricated devices. A digitally controlled reflectarray with MEMS capacitive switches is proposed. This paper aims to determine an appropriate number of phase shifting bits for such implementation. Using array theory, the influence of the number of bits on the beam pointing performance is evaluated. A common feed horn is used to illuminate the reflectarrays. In addition, broadside plane wave illumination is also considered for comparison with existing works in phased arrays. Though at certain scan angles the results are different from those for traditional phased arrays, in general the results are found to be similar. This information lays the groundwork for designing a cost-effective digital MEMS reflectarray cell.