Analysis of the directivity of pattern-steerable short-wave four-limb delta antenna

A four-limb delta antenna was used as the radiator of the pattern-steerable short-wave antenna system. The directivity of the antenna was mainly analyzed here. The current excitations of the four limbs have identical amplitude but 90-degree phase difference between each succeeding elements. It can get a maximal radiation at the direction of the element with lag phase according to the calculation result. There are four feeding methods according to the feeding principle above. Therefore, if get the four-limb delta antenna together with a feeding network and a digital phase shifter network, the antenna would form beams on four basal directions. And then through a switch system to choose one of the four directions that was needed to achieve the function of pattern-steerable.