A printed log-periodic antenna based on fractal tree elements

The well-known frequency-independent antennas are radiating structures capable of maintaining consistent impedance characteristics over wide bandwidths. Their finite size limits the lowest operation frequency and the finite precision of the center region bounds the highest frequency of operation. Particularly for VHF and UHF frequency ranges, the antenna size might be a limitation for many applications. This work proposes a technique for size reduction and gain equalization using a printed log-periodic based on a fractal tree geometry. Numerical and experimental results demonstrate a size reduction of 50.57%, bandwidth of 96% at 810 MHz and gains up 8 dBi.