Sierpinski-like fractal ultra-wideband antenna with triple-band-notched characteristics

In order to avoid the interference conflict of narrow-band communication system to ultra-wideband (UWB) system, a Sierpinski-like fractal UWB antenna with triple-band-notched characteristics is proposed. The radiating patch adopts a second-order Sierpinski-like fractal structure with circular and pentagonal nested iterations, and uses the defective structure ground plate to achieve good ultra-wideband characteristics. By adding symmetrical inverted L-shaped open branches on the upper part of the fractal structure,and adding symmetrical L-shaped open branches on both sides of the microstrip feeder, and etching the inverted π-shaped narrow slit at the feeder produces notch characteristics of the 4.5–4.8 GHz, 7.2–7.8 GHz and 8.0–8.5 GHz bands. The simulation and measured results show that the antenna is effective in suppressing interference from narrow-band systems such as the international satellite frequency band, the X band satellite and the ITU-band in the 3.1–18.1 GHz band. In addition to the filtering frequency band, the antenna has relatively stable gain and omnidirectional radiation characteristics in the passband, and can be used in various ultra-wideband systems.