The ability to control the propagation or radiation of electromagnetic waves is important for many practical applications. This capacity has been explored across the electromagnetic spectrum, with applications in both the near-field and the far-field. For instance, highly directive antennas have been developed using reflectors and directors, constructive interference of multiple antennas in phased arrays, and the engineering of the electric and magnetic dipoles to satisfy Kerker conditions, leading to constructive interference in one direction and destructive interference in the other direction. Despite these strides in far-field directionality control, gaps and opportunities abound for further discoveries. On the other hand, electromagnetic wave near-field directionality has been under-explored until recently, especially in the microwave regime. The discovery of directional dipole sources by manipulating the local polarization or symmetries of confined fields has led to breakthrough applications in directive waveguiding. The basic directional dipoles with near-field directionality are the circular dipoles, the Huygens dipole and the Janus dipole. In this research work, we attempt directive radiation using much fewer elements than previously explored using the near-field property of the Huygens source. Thereafter, we explore the distinctive near-field properties of the directional dipoles to near-field directive waveguiding.

This thesis presents two models of a new beam-steerable antenna inspired by Huygens metasurface – 2D co-located electrically and magnetically polarised dipoles with forward-only radiation in both the near-field and far-field. The TEM antenna wraps an artificial dielectric medium built from equispaced conductive rods with a thin sheet of the metasurface. The metasurface is built from sufficiently spaced simplified Huygens dipoles arranged around the enclosure’s periphery. On the other hand, the TM1 model employs two layers of Huygens metasurface sheet to enclose a region of interest. In both cases, we explored the generation of single beams and multiple beams from the synthesized cavity waves in the Huygens boxes. We also show that in both cases, we achieve complete steerability of the azimuth radiation while the elevation direction can be steered reasonably. For the example 4λ₀ × 4λ₀ square aperture presented in this thesis, we observe that the antennas perform similarly to a microstrip patch array of similar aperture size. Hence, through the proposed antenna, we achieve a many-fold reduction in cost as the element dependency shifts from an area-based one to a perimeter-based one. The reduction ratio and consequent savings in cost become even larger with increasing aperture size.