Study of transitions for the single-wire waveguide at THz frequencies

Several designs for THz waveguiding have been proposed during last years. Among them, a very simple structure, the single-wire waveguide, has received special attention due to its low losses and low dispersion. Unfortunately, this waveguide presents strong radiation on bends. A possible solution to this problem consists in using dielectric-coated wires of small radius, but losses and dispersion increase noticeably. The best solution would be the use of the coated wire only on the curved path. This paper studies the transition from the wire to the dielectric-coated wire and determines an optimized design. Also, the improvement achieved regarding to the standard case is shown.