Experimental Characterization of 2 × 2 Electronically Reconfigurable 1 Bit Unit Cells for a Beamforming Transmitarray at X Band

This paper proposes a reconfigurable unit cell for a transmitarray operating at the X band. The unit cell consists of an active patch, a passive patch, and a phase shifter. The active patch has two PIN diodes that change the phase of 180° of the transmitted waves. The passive and active patches both have circular slots to enhance the bandwidth of the transmitted wave. We also propose a new type of experimental characterization technique to measure the performance of the unit cells at the X band without fabricating the entire transmitarray. Instead of a 1 unit cell as described in the literature, we propose 2 × 2 unit cells to measure the performance of unit cells using the X band waveguide. The waveguide consists of a WR-90 section and a rectangular to square waveguide transition section that can be fit to our proposed structure. A good agreement between simulated and measured results was found.