Design of miniaturised UWB log-periodic end-fire antenna using several fractals with WLAN band-rejection

摘要

Several microstrip log-periodic antennas are introduced having square Koch, triangular Koch, tree and Giuseppe Peano fractals applied to the edges of their branches with substrate integrated waveguide feed system. The proposed antennas are designed for end-fire radiation and ultra-wideband (UWB) operation (3.1–10.6 GHz), which achieve a fidelity factor of better than 0.9 due to the low variation of their phase centres. These antennas are effectively miniaturised and are suitable for impulse radio-UWB and medical imaging. To prevent interference with commercial bands of 5.8 and 8.3 GHz, two spiral slots are cut on the patch. Their frequency and time-domain operations and also miniaturisation are compared with those in the available literature. A prototype model of an end-fire log-periodic microstrip antenna with the Giuseppe Peano fractal applied to the edges of truncated rhombic branches is fabricated and measured to evaluate and demonstrate its stated properties and specifications.