  The design, simulation and measurement of a beam steerable slotted waveguide
antenna operating in X band are presented. The proposed beam steerable antenna
consists of a standard rectangular waveguide (RWG) section with longitudinal
slots in the broad wall. The beam steering in this configuration is achieved by
rotating two dielectric slabs inside the waveguide and consequently changing
the phase of the slots excitations. In order to confirm the usefulness of this
concept, a non-resonant 20-slot waveguide array antenna with an element spacing
of d = 0.58{\lambda}0 has been designed, built and measured. A 14 deg beam
scanning from near broadside ({\theta} = 4 deg) toward end-fire ({\theta} = 18
deg) direction is observed. The gain varies from 18.33 dB to 19.11 dB which
corresponds to the radiation efficiencies between 95% and 79%. The side-lobe
level is -14 dB at the design frequency of 9.35 GHz. The simulated co-polarized
realized gain closely matches the fabricated prototype patterns.
