Analysis And Design Of Self-Structuring Antennas

Various secrecy frequency-hopping communication systems and spread-spectrum communication systems are widely used as ultra wideband, large capacity and multi-functions integration communication systems quickly developed. Higher requests are brought forward for antennas using in these systems, such as broadband, miniature and other electrical shapes. Self-structuring antennas (SSA) have many electromagnetic shapes as there are many controllable switches equipped on the antenna. Thus self-structuring antennas are capable of altering their electrical shape in response to their electromagnetic environment by controlling the states of the controllable switches. Being associated with the National Science Foundation, Smart Self-structuring Antenna, this dissertation makes deeply insight to the theory analysis and experimental research. This work shows potential applications of self-structuring antennas. The major contributions are as follows:The optimal algorithm of genetic algorithm combined with method of moment is proposed to optimize the states of self-structuring antenna. A self-structuring monopole is proposed to introduction the characteristics of self-structuring antenna. The monopole is analyzed by 4NEC (Numerical Electromagnetic Code) and many related experiments are done to illustrate the basic mechanism of the self-structuring antenna.In this dissertation, the study is emphasis on the rectangle ring self-structuring antenna. The optimal algorithm is studied to analyze and design the rectangle ring self-structuring antenna by genetic algorithm (GA) combined with method of moments (MOM). The electromagnetic configurations are optimized at 5MHz intervals, and the optimized switches'states which represent the electromagnetic configurations are stored in singlechip. In experiments, the network analyzer is used to measure the VSWR of the SSA at 5MHz intervals, and the switches states are controlled by singlechip. Thus the VSWR curve can be got in the whole frequency band. The simulated and experimental results show that more than 10:1 frequency band with the VSWR less than 2.A triangle ring self-structuring antenna with fractal structure is studied, which has the configuration of sierpinsiki gasket. The NEC2d is used to analyze and design the antenna, and the results show that this antenna can achieve wideband and miniaturization.Based on the analysis of the rectangle ring self-structuring antenna, a wideband linetype monopole with G type structure is proposed and analyzed by 4NEC. The G type monopole is designed at 1GHz, and works on 0.86GHz~1.37GHz. The simulated and experimental results have demonstrated that the proposed monopole can achieve more than 51% frequency band with the VSWR less than 2. The relative bandwidth shows the good electrical characteristics of this kind of monopole.