Reflectarray with logarithmic spiral lattice of elementary antennas on its aperture

A reflectarray with logarithmic spiral lattice of elementary antennas on its aperture is presented. In a logarithmic spiral lattice, elementary antennas are arranged in a grid of an outwardly spiral so as to have no translational periodicity. Infinite array approach has been used to determine reflection phase curve since in the aperiodic logarithmic spiral lattice, the effective unit cell area remains the same. Based on this lattice, a prime focus fed reflectarray centered at 16 GHz has been designed and developed. The measured gain is 30.5 dBi and side lobe levels are −29 dB and −22 dB in E- and H-plane respectively. Aperture efficiency of the proposed reflectarray is 37% and its 1-dB gain bandwidth is 4.1%. Good agreement between measured and simulated results reinforces the validity of the design process. A comprehensive investigation of reflectarrays’ performance with different lattices is conducted which shows lower side lobe levels for reflectarray with logarithmic spiral lattice.