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.