Analysis and Design of Slitted Waveguides With Suppressed Slot-Mode Using Periodic FDTD

Improved Design of Uniform SIW Leaky Wave Antenna With Suppression of Unwanted Mode

“…Although in [8] and [11] periodic transverse slots are used, it should be noted that those designs are narrow-wall-related slitted waveguide, which are different from our broad-wallrelated design. In fact adding periodic transverse slots on the narrow wall in [8] and [11] will not perturb the dominant TE10 mode because they will not cut the currents on this wall.…”

“…Although in [8] and [11] periodic transverse slots are used, it should be noted that those designs are narrow-wall-related slitted waveguide, which are different from our broad-wallrelated design. In fact adding periodic transverse slots on the narrow wall in [8] and [11] will not perturb the dominant TE10 mode because they will not cut the currents on this wall. Therefore, these transverse slots will not influence the operation of the original narrow-wall slitted waveguide; they just work as series inductors to slow down the propagation speed of the slot mode (fast wave unwanted mode) and to transform it to a slow-wave unwanted mode.…”

“…This spoils the radiation pattern by creating an undesired beam or broadening the main beam. For this reason, some investigations have been done for identification and suppressing the slot mode radiation [7], [8], [11]. Suppression of the slot mode by thin-film metal or dielectric sheet in [7], causes a significant gain drop.…”

“…Suppression of the slot mode by thin-film metal or dielectric sheet in [7], causes a significant gain drop. In [8] and [11], periodic transverse slots are added perpendicular to the longitudinal slot on the narrow wall to change the slot mode propagation from a fast wave to a slow wave. In this manner, some amount of power is guided in the waveguide and absorbed at the load.…”