Ultra-wideband high-gain miniaturized log-periodic antennas

In this letter, an ultra-wideband high-gain miniaturized log-periodic antenna (LPDA) is proposed. The antenna significantly reduces the size of the antenna by introducing the Kcoh fractal dipole technology while maintaining its overall performance characteristics; meanwhile, the parasitic patch is added to broaden the low-frequency bandwidth and improve the antenna gain. The size of the final antenna is $100 \mathrm{~mm} * 50 \mathrm{~mm} * \mathbf{0. 7 6 2}$ $\mathbf{m m}$, and the maximum size of the oscillator patch is less than 0.2 wavelength of the lowest operating frequency. The simulation results show that the impedance bandwidth of the antenna is 186% $(1.44 \mathrm{GHz}-40 \mathrm{GHz})$ when the in-band return loss is less than $\mathbf{- 1 0 ~ d B}$, and the VSWR is less than 2 at $1.39 \mathrm{GHz}-40 \mathrm{GHz}$; the gain is more than 10 dB at $13.79 \mathrm{GHz}-40 \mathrm{GHz}$, and the maximal gain is 12.69 dB, and the minimal gain is 6.04 dB.