PHASE
SHIFTER
In transmission, when beam from a particular direction is desired,
antenna is rotated to that direction. But in modern transmission systems
beam steering can be done by phased array antenna. Despite limited
bandwidth this type of antenna can steer main beam of radiation by phase
shifters and reduce the effect of side lobes. [4]. Phase shifters
are categorized as mechanical phase shifters, ferrite phase shifters,
semiconductor device phase shifters and transmission line phase
shifters.[7].the phased delay in the feed network can be obtained
from (12).
\(\Delta L=\frac{\beta_{0}}{2\pi f\sqrt{\varepsilon_{\text{eff}}}}\)(12)
Where β is propagation constant, Ɛeff is effective
dielectric constant and c is speed of light. Based on equation (12) the
final design was done by adding phase shifters to feed lines to steer
beam for admired direction of 40 degree.