| With the rapid development of modern information and communication technology and the continuous upgrading of electronic equipment, the communication band is de-veloping to multiband and broadband. As an important terminal equipment of wireless communication system, antenna's performance has important influence on the whole system. Based on the analysis of antenna theory and numerical algorithm,in the premise of study of a large number of loading model, the paper take the slot loading, coupled resonant stub loading, capacitance loading and fractal geometry structure technologies into comprehensive application. The antenna design inspiration comes from the natural and cultural characteristics,the paper puts forward the China classical traditional patterns and bionics characteristics into the design of antenna structure. The antenna geometry with the classical elements Chinese structure (coins,window applique and back lines) and natural plant appearance (branches, flowers)graphic features of fusion innovation,using the electromagnetic coupling relationship between various loading by controlling the depth dimension, multi-frequency broadband and miniaturization, high performance and performance in mobile coverage antenna terminal.3D electromagnetic simulation software HFSS is used to build and optimize the simulation model of antenna in the design. The antenna models with different evolutionary states and different iterations are compared. The resonance impedance,the amplitude and vector surface current, the far field 3D gain, the directional pattern in E/H plane, the cross polarization, the gain and efficiency of antennas are studied by simulation. In order to facilitate the performance of different antennas, the PTFE glass cloth plate (FR4) with dielectric constant of 4.4 and thickness of 1.6mm are selected as the medium plate materials, developed three major categories of 9 novel multi-frequency broadband and miniaturized antennas with high radiation characteristics. The testing results including return loss, radiation pattern, gain and efficiency other related performance parameters.The main work and innovations are summarized as follows:1. The traditional fractal structure (Koch snowflake, Sierpinski triangle pad) is applied to improve the monopole microstrip antenna and proposes four novel antennas structures, these are as the follows. 1) two iterations Koch snowflake and 4 iterations Sierpinski triangle pad are combined and the antenna's size is 80*54mm ,works at six bands with 1.22-1.54GHz, 1.86-2.12GHz, 0.85-0.96GHz, 2.4-3.22GHz,3.69-3.97GHz and 4.84-5.98GHz frequency bands, the gain is 1.39-4.94dBi. 2) A multiband Koch snowflake fractal ring antenna works at 3.37-3.8GHz and 4.12-5.95GHz in 1.4-3.13GHz frequency bands, the size is 72*42mm2, the gain 0.86-2.7dBi. 3) A Koch snowflak ultra-wideband fractal antenna realizes 1.5-4.9GHz ultra-broadband coverage, the gain is -1.7-2.35dBi, the efficiency is 31-64%. 4) 3 iterations Koch snowflake fractal slot antenna works at 2.4-2.95GHz,3.5-4.05GHz in 1.6-2.05GHz,and 5.15-6GHz broadbands, the size is 88.5*58mm , the gain is 0.21-7.79dBi, efficiency is 51-98%.2. Combined with the bionics characteristics, the characteristics of flowers,branches and leaf graphics are used in design of antenna structure,proposed 2 novel antennas. One is a 2 iterations W shaped Fractal antenna just like the petals, the size is 98*56mm2, works at 0.6-1.05GHz,1.45-2.65GHz and4.25-4.55GHz frequency bands, the gain is 1.9-2.4dBi, the efficiency is 44.9-77.8%. The other is 3 iterations two-fork branches shaped fractal antenna, the size is 50*40mm2, works at 1.85-2.9GHz and 4.9-5.5GHz frequency bands.3. China classical elements (coins, window applique and back lines) are integrated into the antenna radiator structure, proposed three novel antennas. 1) From the appearance characteristics of local ancient coins of China, a five iterations radius of nested fractal structure iterative coin fractal antenna is designed. The size is 88.5*60mm2, works at 3.32-3.91GHz, 3.32-3.91GHz in 1.43-2.97GHz, and 4.85-5.41GHz broadbands, the gain is 1.16-3.75dBi, the efficiency is 40-72%; 2)From the characteristics of China classical window applique with inverted triangle structure, within the fourteen element of triangular slot array, the antenna size is 60*55mm2, works at 2.23-2.65GHz, 3-3.52GHz and 4-5.89GHz frequency bands. 3)Referring to the traditional Chinese culture " back lines " structure, four multiband antennas with concentric rectangular open ring slot structures is proposed, the size is 50*40mm2, works at 2.88-3.44GHz and 3.65-4.29GHz frequency bands, the gain is 1.33-4.83dBi, the efficiency is 61-95%.The antennas' testing results and simulation results verify the rationality of the design. The antnnas have the omni-directional radiation characteristics, antenna gain and high efficiency, cover all or part of the communication band applications of GSM900, DCS 1800, TD-SCDMA, WCDMA, CDMA2000, LTE, 5G, Bluetooth,GPS, Glonass, Galileo, Beidou satellite navigation. WLAN and WiMAX. |
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