Improvement of folded dipoles based on a branch current distribution

Folded dipoles are typically used as elements in curtain arrays due to their high input impedance, but under this configuration, the bandwidth of the curtain array in antenna mode is limited. This paper proposes an improved folded dipole based on a branch model, which effectively increases the bandwidth of the input impedance and decreases the VSWR(Voltage Standing-Wave Ratio) by selecting appropriate branch conductor positions. The current distribution of the branch model exhibited an unbalanced condition as the branch conductors moved. To verify the proposed method, a practical model with a cage antenna was analyzed using the proposed method and FEKO. The results indicated that the bandwidth reaches a maximum when the factor k_BP is between 0.4 and 0.5.