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

Abstract

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.

Flexible Manipulation of Emitting Beams Using Single‐Aperture Circularly Polarized Digital Metasurface Antennas: Multi‐Beam Radiation toward Vortex‐Beam Generation

“…Recent years have witnessed a clear tendency toward achieving multiple contour beams using fully planar metasurface‐based devices with a lighter weight and lower cost compared to the solid reflectors [ 6 ] and bulky metamaterials. [ 7 ] Metasurfaces, engineered arrays of artificially patterned microelements on a flat surface, have recently emerged as a flourishing concept which attracts tremendous interest because of providing peculiar routes to manipulate the phase, [ 8–10 ] polarization, [ 11 ] amplitude, [ 12–14 ] transversal shape, [ 15,16 ] and trajectory [ 17–20 ] of the electromagnetic (EM) fields. Since Capasso's group introduced the generalized laws of refraction/reflection in 2011, [ 21 ] this 2D version of metamaterials has inspired many exceptional and modern devices, typically in the field of antennas and antenna accessories.…”

Design of open devices based on multi-folded transformation optics

“…AS an ingenious mathematical approach, transformation optics (TO) [1][2][3][4][5][6] provides a powerful and convenient way to control the electromagnetic (EM) fields arbitrarily, arousing much attentions in the past two decades. Based on this methodology, novel devices with varied functions and applications have been proposed, designed and experimented with an unprecedented prosperity, including invisible cloaks [7][8][9][10][11][12][13], concentrators [14][15][16][17][18], illusory devices [19][20][21][22][23][24][25][26][27][28] and antennas [29][30][31][32][33][34][35] etc. The most striking device among them is invisible cloak, where some properly designed materials are utilized to direct the EM waves propagates smoothly around an arbitrarily shaped object, making the entire device (including the coated object) become invisible for the outside viewers.…”

Bi-Functional Antenna Coating for Cloaking and Directivity Enhancement Made of Isotropic Materials

“…Moreover, TO has been combined with microwave devices such as waveguide bend, which connects two waveguides even with different size at different angles without any EM field perturbations [6]. Besides, the theory of TO opens up new horizons for the antenna designs like antenna lens [7], antenna beam steering [8] and antenna pattern synthesis [9]. In [9] the authors propound a general approach for enabling the customizable multiple beam radiation of planar antennas.…”