Experimental demonstration of metamaterial-assisted antenna beam deflection through folded transformation optics

Based on the folded transformation optics, a methodical approach for manipulating the orientation and directivity of a planar antenna beam is propounded. Unlike the classical phased array antennas, the tilted emitting beam is achieved by a homogeneous metamaterial-based superstrate in a triangle shape configuration, rather than by utilizing complicated and bulky phase shifters. Such a simple coating layer is elaborately designed via folding the virtual space to physical one with an affine transformation. The competency of the proposed method is demonstrated through some examples, indicating the capability of the coating layer in tilting the radiated beam to any desired off-normal directions in both the upper and lower half spaces. To authenticate the concept, a tilted beam metamaterial-based antenna is fabricated and tested; it is observed that the experimental results are in a good agreement with the numerical simulations and theoretical predictions. The presented method paves the way towards steering the beam of a metamaterial-assisted antenna, which has been a topic of great interest in several fields of engineering, such as antenna technologies, satellite communication, and multiple-input multiple-output systems. (paper)