A Flexible Multiband Dendritic Structure Fractal Antenna for 4G/5G/WLAN/Bluetooth Applications

In this study, a flexible multiband fractal antenna mimicking dendrite structure is proposed and designed by combining bionics and fractal theory. The dendritic structure of neurons is extracted and simplified into a simple and clear geometric structure. The initial antenna model is obtained by fractal operation on the geometric structure, and finally, four effective bands are obtained. The antenna is printed on a ${50}^{\ast }{70}^{\ast }0.1$  mm3 polyimide dielectric board and fed by a coplanar waveguide. This paper discusses the effect of the human body on the performance of the antenna and the robustness of the antenna in the bending regime. The gain, efficiency, and cross-polarization of the antenna were tested using a microwave anechoic chamber. The measured antenna covers 1.37 GHz-1.93 GHz (relative bandwidth 35%), 2.25 GHz-2.51 GHz (relative bandwidth 10.7%), 3.13 GHz-3.81 GHz (relative bandwidth 19.3%), and 4.46 GHz-5.5 GHz (relative bandwidth 21.1%) four operating frequency bands. The maximum gain is 6.05 dBi and the maximum efficiency is 91.05%. The antenna can be used for Bluetooth WLAN (Wireless Local Area Network), 4G (4th Generation Communication System), 5G (5th Generation Mobile Communication System), WiMAX (Worldwide Interoperability for Microwave Access), etc. The test results are in good agreement with the simulation results, which proves that the antenna can meet various wireless communication requirements.