Due to their frequency-dependent angular emission, leaky-wave antennas have been recently introduced in the terahertz band to tackle many of the challenges associated with THz wireless communications. Most previous works have exploited conventional leaky-wave waveguide architectures developed for the microwave region. In this paper, we study in detail the emission characteristics of leaky-wave antennas at THz frequencies. We show that, at these high frequencies, the wavelength-scale interaction with the aperture causes a nonuniform electric field distribution at the slot interface, which is a unique regime that is not typically encountered at lower frequencies. This effect is even more pronounced as the slot width increases to a point where the sides of the slot act as secondary leaking structures, and the well-known frequency–angle relationship is not obeyed as the energy at a given frequency is radiated in a broad range of angles. Therefore, to exploit the phase matching condition, which couples frequency to emission angle, one must use very thin rectangular slots d≪λ, at the expense of device efficiency. To address this problem, we explore an alternate slot aperture design, in which the slot width increases linearly along its length (i.e., a trapezoidal shape). We show that this preserves the phase-matching constraint while allowing higher output coupling efficiencies. Moreover, since a wider effective aperture is used, the radiated beam is narrow in both angular directions, allowing the generation of true pencil-like THz beams.
We study the radiation properties of leaky-wave antenna at terahertz frequencies for wireless communications. We introduce a novel aperture design that increase the efficiency and directionality of the generated beams.
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