A Reflectarray Antenna Using Hexagonal Lattice With Enhanced Beam Steering Capability

This paper presents a novel reflectarray antenna with enhanced beam steering capability. The reflectarray antenna is based on the hexagonal distribution of the unit cells on the antenna surface. The hexagonal topology changes the angle between the principal axes of the unit cell distribution, preventing the formation of the grating lobe, and improving the beam steering capability of the reflectarray antenna. To verify the proposed idea, two different sets of reflectarray antennas, which includes square and hexagonal lattice topologies with inter-element spacings of <inline-formula> <tex-math notation="LaTeX">$0.52\lambda $ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$0.6\lambda $ </tex-math></inline-formula>, have been designed, fabricated, and measured at 8.23 GHz. The measurements of the all fabricated reflectarray antennas are in very good agreement with the simulations, and the comparison of the square and hexagonal topologies show that the beam steering capability can be improved by 50% for <inline-formula> <tex-math notation="LaTeX">$0.6\lambda $ </tex-math></inline-formula> inter-element spacing by using a hexagonal topology. This improvement shows that a simple modification in the array configuration can be a viable solution for satellite and 5G communication applications that require increased beam steering capability.