Refractive index reconfigurable metamaterial structure at 28 GHz frequency range

In this paper, a new refractive index reconfigurable metamaterial structure at millimeter wave (MMW) frequency range has been designed and simulated for beam switching in a future fifth-generation (5G) mobile network applications. The new proposed structure is composed of a Ladder shaped resonator (LSR) printed on the front face of a substrate layer and operates at 28 GHz. By proper arrangement of LSR unit cell, the proposed structure achieves a low loss and almost full transmission by −0.26 dB (0.97 in linear scale). To provide the refractive index reconfigurable feature, two PIN diodes are formed in the gaps of the structure. Thus, LSR can be switched between four states with a different refractive index values which are −60, −14, 0 and −12 at 28 GHz. In the simulation, the copper strip and measured S-parameters of the proposed PIN diode are used to achieve the reconfigurability. To demonstrate a reconfigurability of the new metamaterial structure, the return loss, insertion loss and real parts of the effective refractive index at each reconfigurable frequency are studies and investigated.