Amplitude-Reconfigurable Unit Cell in CLAF-SIW for Beamforming Applications at mmWaves

This work presents an amplitude-reconfigurable unit cell for the design of active 1D metasurfaces at the millimeter-wave frequency range. The reconfigurable unit cell consists of a contactless air-filled substrate-integrated waveguide (CLAF-SIW) that feeds an SIW cavity with a ring-shaped slot as a radiating element. In order to perform the reconfiguration, two PIN diodes are placed in the ring-shaped slot. The CLAF - SIW allows reduced losses while feeding the reconfigurable SIW cavities in a progressive form as a leaky-wave antenna. The structure requires a single layer for the radiating elements and only two for the feeding layer since the radiation layer completes the CLAF-SIW. For the implementation of beamforming at 40 GHz, a method of switching OFF/ON in each reconfigurable unit cell is applied. By optimizing the state of each unit cell in the reconfigurable leaky-wave antenna, various radiation patterns can be achieved.