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In order to curtail mutual coupling between two closely spaced microstrip monopole antennas operating at frequencies 28 GHz and 39 GHz, the concept of electromagnetic cloaking is applied by utilizing elliptical metasurfaces. In this paper, we show that by enveloping the monopole antennas with the specifically engineered metasurface cloaks, not only is there a significant reduction in the mutual electromagnetic interaction but also restoration in the radiation patterns are observed, as if the antennas were completely isolated from each other. The decoupling effect is seen in the reduction of mutual S-parameters. This enables the antennas to radiate independently even though they are placed in a very close proximity. 

Abstract Structured waves are ubiquitous for all areas of wave physics, both classical and quantum, where the wavefields are inhomogeneous and cannot be approximated by a single plane wave. Even the interference of two plane waves, or of a single inhomogeneous (evanescent) wave, provides a number of nontrivial phenomena and additional functionalities as compared to a single plane wave. Complex wavefields with inhomogeneities in the amplitude, phase, and polarization, including topological structures and singularities, underpin modern nanooptics and photonics, yet they are equally important, e.g., for quantum matter waves, acoustics, water waves, etc. Structured waves are crucial in optical and electron microscopy, wave propagation and scattering, imaging, communications, quantum optics, topological and non-Hermitian wave systems, quantum condensed-matter systems, optomechanics, plasmonics and metamaterials, optical and acoustic manipulation, and so forth. This Roadmap is written collectively by prominent researchers and aims to survey the role of structured waves in various areas of wave physics. Providing background, current research, and anticipating future developments, it will be of interest to a wide cross-disciplinary audience.