Nonlinear optimization reduces the sidelobes of Yagi antenna

The radiation pattern of the Yagi antenna is optimized by the conjugate-direction method. The actual solution of the integral equation for current distribution is used throughout the optimization. A study of several Yagi antennas optimized by Morris shows that, for fixed distances between elements, the directivity cannot be improved further, but the sidelobes can be reduced by as much as 10 dB.