Design Methodology for a Reactively Loaded Yagi–Uda Antenna

To design reactively loaded antenna arrays, a basic design methodology is proposed that combines superimposing the electric field of each antenna element along with multiobjective optimization. The design methodology is demonstrated in a three-element, reactively loaded, symmetrical, compact Yagi-Uda antenna. Because the antenna is symmetrical, the reactive loads can be used to steer the maximum gain of the antenna in two directions. The antenna maintains a high absolute gain and low VSWR over a 10% fractional bandwidth with an element spacing of 0.053λ. The antenna requires a simple matching circuit to maximize the impedance match of the antenna.