Optimal Directional Antenna Arrays Designed For VHF And UHF Applications

Abstract

In most of the applications it is essential to design an antenna with performance newlineparameters such as high Directivity (DR), narrow Half Power Beam-Width (HPBW) newlinelow Side-Lobe Level (SLL), high Front to Back Ratio (FBR), high Band Width (BW), newlinelow Voltage Standing Wave Ratio (VSWR), nulls in desired directions, proper input newlineimpedance (Zin), etc., to fulfill the demands of long-range wireless communication. In newlinethis regard single element antenna is not suitable so-far-as these performance newlineparameters are concerned. Therefore, to achieve the Desired Performance Parameters newline(DPPs), a suitable antenna is preferred. The DPPs are the non-linear function of all the newlinedesign parameters. In such a situation formulation of a proper Multi-Objective-Multi- newlineParameter (MOMP), non-linear objective/fitness function is highly essential to attain all newlinethe DPPs. In this dissertation, five different array structures are considered and newlinesubsequently designed optimally to achieve some of the above-mentioned performance newlineparameters for VHF and UHF applications. In fact, the conventional arrays designed as newlineper the theory in textbook do not provide the DPPs. Therefore, suitable robust newlineoptimization techniques need to be used to achieve optimal designs. In this regard, newlinesome of the important optimization techniques used in the dissertation are: Bacteria newlineForaging Optimization (BFO), Particle Swarm Optimization (PSO), Cuckoo Search newlineOptimization (CSO), Gravitational Search Optimization (GSO), Biogeography Based newlineOptimization (BBO), Fuzzy-logic biased GSO (FGSO), Fuzzy-logic biased BBO newline(FBBO), and Taguchi s Method of Optimization (TMO). newline newline