A Novel Chrysanthemum-Like Fractal Structure Multi-Band Antenna for Mobile Terminals

Abstract

This paper incorporates the structural characteristics of chrysanthemums in nature and fractal geometry theory into the antenna structure design and a novel-structured fractal multiband fractal microstrip antenna with a chrysanthemum petal structure is proposed. The antenna can cover commercial frequency bands from the second to fourth generation (4G), satellite navigation, wireless local area networks, and Bluetooth. The antenna radiator imitates the structure of chrysanthemum’s petals in nature, and a basic arc shape is iterated many times according to a certain proportional coefficient. After simulation and comparison, the second iteration can achieve the best antenna performance, and the antenna adopted the coplanar waveguide feeding method to broaden the antenna bandwidth. The antenna covers three effective frequency bands of 1.58–2.68 GHz (64.7%), 2.76–4.01 GHz (33.9%), and 4.68–5.35 GHz (13.4%). The antenna dielectric board is made of FR-4 material, the dielectric constant is 4.4, and the actual size is 41 × 29 × 1.6 mm3. The antenna performs fractal iteration at a small size, and the approximate calculation of the frequency band is completed by comparing the ratio of each ring to the current vector diagram. The design of the antenna is to use HFSS for antenna modeling and parameter optimization, and the model under different conditions were compared and analyzed. By comparing the test results of the antenna prototype with the simulation structure in the electromagnetic anechoic chamber, the rationality of the antenna is verified.