| The ultra-wideband (UWB) antenna is an important and indispensable component of UWB wireless systems. The antenna undoubtedly plays a very important role for the UWB technology widely used in many areas such as radar, positioning, detection and control. So in recent years, the study of UWB antennas and array becomes hot investigation, as well as one of the important research directions in the UWB technology. This paper is mainly focused on the rapid design methods of the UWB antennas and array.The simulation of the electrically large UWB antennas and array needs long time and great memory, and even one computer sometimes can not complete the calculation. In order to solve this problem, some highly efficient parallel finite-difference time-domain (FDTD) methods for the large-scale parallel platform are studied, based on the "J parallel Adaptive Structured Mesh applications Infrastructure"(JASMIN) framework. Firstly, the uniform grid parallel FDTD method and its key technologies are studied and verified. Then the144-element TEM horn and Ridged TEM horn antenna array are calculated using500processors. Secondly, the gradual non-uniform parallel FDTD method is studied, which can effectively decrease memory requirements and computational effort problems by comparison with the uniform grid FDTD method, when the antennas and array have fine structure. Using this parallel algorithm, the radiation characteristics of a64-element spiral antenna array is simulated on200processors. Finally, the parallel body-of-revolution FDTD (BOR-FDTD) method is studied for fast solution of the antenna with rotationally symmetric structure. A standard Cassegrain antenna is parallel computed and the diameter of its main reflector is280wavelengths.The UWB antennas and array involve many parameters, as well as the relationship between the parameters and design goals is nonlinear. Therefore it is necessary to introduce global optimization algorithms for antennas and array aided design. The performance of optimization algorithms will directly affect the performance of the antennas and array, as well as the design time. In order to improve the performance of global optimization algorithms, the parallel micro genetic algorithms and integer coded differential evolution strategies are first studied. The coarse-grained and fine-grained parallel MGAs, integer coded DESs are applied to a32-element linear array pattern synthesis problem. It is shown that performance of the parallel algorithms is better than the serial optimization algorithms and the DES proposed in a literature. Then a hybrid optimization algorithm (HDECACO) based on DES and continuous ant colony optimization (CACO) algorithm is proposed to improve the search ability. Two representative mathematical functions are minimized using the HDECACO algorithm and the convergence rates are compared to prove its high efficiency.Subsequently, the proposed parallel global optimization and HDECACO algorithms focusing on the design of UWB horn antennas are discussed. The parallel optimization algorithms and the3-D uniform grid FDTD method are combined to achieve an automated parallel design process for TEM horn antenna. The results show that the parallel MGAs can be better to maintain the population diversity, and have stronger search ability. In order to design high efficient feeds for reflector antennas, the multimode conical horn antennas are studied. The automatic optimization design with combination of BOR-FDTD and global optimization algorithms is proposed. The HDECACO algorithm is applied to optimize the multimode conical horn antennas with a step of radius and multi-section changing flare angles. The feasibility of automatic design is verified And then the fine-grained parallel MGA is used to design a corrugated conical horn antenna in the8-13GHz. In the entire operating band, the tapered edge irradiation, gain and main lobe width have preferably constant values, and the voltage standing wave ratio is less than1.5.Thereafter, the paper studies the planar ultra-wideband (UWB) antennas and power divider. The hot research directions related to planar UWB antennas is carried out. A novel compact ultra-wideband planar antenna fed by a microstrip line is proposed. It has been demonstrated that the proposed printed compact antenna can achieve a good impedance bandwidth,2.1-2.6GHz and3.3-20GHz. Within the whole UWB band (3.1-10.6GHz), there still exist several narrow bands for other communication systems,, which may cause severe electromagnetic interference to the UWB system. Therefore, it may be necessary to have a notch for those bands in order to avoid potential interference. In this paper, two new simple dual band-notched printed antennas with variable frequency band-notch characteristic are proposed, unlike the commonly used methods. Only by using the split ring resonator and U-shaped parasitic elements on the back side of the radiation patch, two desirable operating bands can be achieved for the proposed antennas. The application requirements of UWB planar directional radiation antennas are also considered here. A tapered microstrip line comprising exponential and elliptic sections is applied to achieve the UWB performance and miniaturization design for the Vivaldi antenna. By using this technology, an UWB power divider is designed, which is optimized by the combinatorial method of the coarse grained parallel PMGA and a commercial electromagnetic software. The optimized power divider exhibits better performance. Finally, The HDECACO algorithm is applied to design an E-shaped wideband patch antenna, which achieves the impedance bandwidth4.8-6.53GHz. The advantage of this hybrid method over the DES and the CACO is also demonstrated.At last, the parallel MGAs and HDECACO algorithm are applied to UWB antenna arrays optimization problems. Firstly, a49-element TEM horn antenna array is optimized by the master-slave parallel MGA. The fitness values are calculated by parallel FDTD method on200processors, and the optimization time is reduced. Secondly, the active element pattern (AEP) method is used to solve the array radiation problems. The AEP method is very effective because it includes the effects of mutual coupling rigorously for computing the far-field pattern of a fully excited array. The array patterns calculated by this method are in good agreement with the results by the full-wave simulation of commercial software. The UWB antenna arrays can be fast designed by combining with the proposed global optimization algorithms:A8-element H-plane linear UWB Vivaldi antenna array in the same phase is optimized by the HDECACO algorithm. The excitation amplitudes are as the optimization variables. Compared with the uniform amplitude and-30dB Chebyshev antenna array, the side lobe level (SLL) obtained by the optimization algorithm is lower. Using the fine-grained parallel MGA, the excitation amplitudes of the256-element rectangular lattice and200-element triangular lattice E-shaped patch antenna array in the same phase is as the design parameters. To the4-circle60-element concentric circular ring E-shaped patch antenna array, the design parameters to be optimized are excitation phases and amplitudes. The optimization time is effectively reduced, and good results are achieved. |
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