Design of a Compact Log-Periodic Dipole Array Using T-Shaped Top Loadings

A compact log-periodic dipole array (LPDA) is presented with size-reduced dipole elements. With T-shaped top loading, the length of individual dipole elements is reduced by 45% compared to that of λ/2-dipole elements. The compact LPDA is simulated and fabricated for measurement verification. The measured 10-dB impedance bandwidth is 87.3%, and the average realized gain in the direction of the shortest dipole is 5.1 dBi over the operating bandwidth.