多阶振幅量化加权二维固态有源相控阵天线的设计与分析

本文论述了一种多阶振幅量化二维固态有源相控阵天线获得低副瓣的口径设计方法，这种方法可适用于任意复杂口径天线，另外，对于由随机幅相误差和单元（或（Ｔ／Ｒ）组件）失效而引起的幅瓣电平恶化和增益下降也进行了分析。     

固态有源相控阵天线多阶振幅量化及副瓣特性的研究

本文研究了多阶振幅量化二维低副瓣固态有源相控阵天线的口径设计方法，结果表明，这种方法能够有效地降低固态有源相控阵的峰值副瓣电平，并且可适且于任意复杂口径天线。另外，对于随机幅相误差和单元（或Ｔ／Ｒ组件）失而引起的增益损失及峰值副瓣电平恶化也进行了分析。     

多阶振幅量化加权二维固态有源相控阵天线的设计与分析

本文论述了一种多阶振幅量化二维固态有源相控阵天线获得低副瓣的口径设计方法,这种方法可适用于任意复杂口径天线。另外,对于由随机幅相误差和单元(或T/R组件)失效而引起的副瓣电平恶化和增益下降也进行了分析。     

平面相控阵天线容差分析

分析在单元馈电随机幅相误差，单元了胡机位置误差，单元失效，及由行，列馈造成的行，列相关幅相随机误差综合作用下，椭圆阵列天线的副瓣恶化；     

部件失效对有源相控阵天线性能的影响分析

有源相控阵天线系统的部件失效会造成天线增益、副瓣电平等性能参数的恶化。在考虑了天线单元幅度和相位的随机误差呈正态分布后,以部件失效的概率分布为依据,分析了包括天线单元失效、子阵失效以及组件失效情况下,天线性能随之变化的趋势。通过算例仿真得出,在文中建立的不同部件失效的数学模型下,天线增益的变化相对平缓,而副瓣抬升则相对较大。计算结果及结论可用于实际相控阵天线性能的评估和工程设计。     

二维固态有源相控阵失效单元补偿新方法

提出二维固态有源相控阵失效单元补偿的新方法，该方法基于失效单元矩形切割和线性规划方法。可适用于有源阵列多单元任意失效分布的实时补偿。在保证失效补偿后两主平面副瓣性能完全恢复的情况下，用线性规划方法对空间平均融瓣进行了优化。由于采用实数算法，仅需对非失效单元的幅度进行调整。理论分析及模拟计算表明该方法在工程应用中是切实可行的。     

运用遗传算法结合FFT进行多单元失效阵列校准

提出了利用遗传算法（GA）结合快速傅立叶变换（FFT）方法来进行阵列失效的校准,通过引入傅立叶变换的变换域和角域的映射,在变换域中利用FFT计算个体阵列的阵因子,减少了GA评估个体的时间,从而大大提高了失效校准的速度。以一个-35分贝副瓣电平的32单元阵列为例,校准一单元失效和二单元失效的时间都减少了至少一个数量级,算法也可应用于两个以上单元失效的情况。     

基于改进遗传算法的阵元失效校正方法

阵列天线中阵元失效,其方向图的副瓣电平会升高、主瓣变宽。保留遗传算法前期迭代的最优个体为新初始种群对遗传算法进行改进,以加快收敛速度和防止最佳染色体缺失。并利用基于优势保留的改进遗传算法,针对-40dB 的26 单元阵列,随机缺失3 单元后进行优化,恢复原方向图副瓣水平。结果表明,该算法能够有效减少阵元缺失后方向图的恶化。     

新型相控阵天线多阶混合馈电技术

提出了一种基于混合遗传算法的新型相控阵天线多阶混合馈电技术,描述了在有限TR组件数量和品种的情况下,可实现相控阵天线低副瓣的技术原理和仿真实例.仿真实例表明,多阶混合馈电阵比密度加权阵和多阶振幅量化阵具有更优的技术指标,且参数调节更具有灵活性,可大大减少相控阵天线成本.且多阶振幅量化阵仅是多阶混合馈电阵的一个特例.此外,对于同时存在随机幅相误差和单元(或TR组件)失效而引起的峰值副瓣电平恶化情况也进行了统计分析.     

含不规则子阵的阵列低副瓣特性研究

对含不规则子阵固态有源相控阵进行了多阶振幅量化,并对其低副瓣特性进行了研究.研究结果表明,利用较少量化台阶数,多阶振幅量化阵可实现较低的副瓣电平.该方法有利于减少组件品种和设计成本,适于工程应用.给出设计实例,验证了不规则子阵多阶振幅量化的正确性.最后,分析了随机幅相误差和单元(或T/R组件)失效对峰值副瓣电平的影响.     

Sidelobe suppression of planar array antennas by the multistage decision method

The sidelobe level of a planar array antenna with equal amplitude excitation can be suppressed by element thinning. The method of element thinning employed here is a kind of multistage decision procedure or steepest descent approach. Although this method gives the local optimum results, the reduced sidelobe level is assured to be within the obtained level over the whole radiation region. The sidelobe level, for example, can be suppressed -29.7 dB where the array contains 3120 elements arranged within a circular aperture capable of 5815 elements if fully filled. The computation time is also discussed, and it is shown that the computation time decreases drastically by the use of the design method.     

Element Failure Correction for a Large Monopulse Phased Array Antenna With Active Amplitude Weighting

Recently a new method is introduced to synthesize low sidelobe patterns for planar array antennas with a periodic element arrangement. The method makes use of the property that for a planar array with periodic spacing of the elements, an inverse Fourier transform relationship exists between the array factor and the element excitations. This property is used in an iterative way to derive the array element excitations from the prescribed array factor. The same method is also able to partially compensate the degradation of the sidelobe and gain performance of array patterns due to element failures. Numerical examples of array-failure correction using this method are given for ultralow sidelobe sum and difference patterns of a 5800-element circular array where the failed elements are randomly dispersed across the aperture. The tapers in this array are created exclusively by active weighting in the transmit/receive (T/R) modules using variable gain control.     

Application of retrodirective beams to achieve low sidelobe levelsin small phased arrays

Synthesis of beams with low sidelobe levels is a difficult problem for the case of small phased arrays with few elements. Mutual coupling between elements means that conventional weighting algorithms are not applicable. A technique is presented that calculates a complex weight vector for a five element linear array, giving a reduced sidelobe beam pattern. Sidelobes are reduced by the addition of retrodirective beams to the quiescent beam pattern. No knowledge of the coupling coefficients or element radiation patterns is required     

Least squares pattern synthesis for conformal arrays

The problem of synthesising low sidelobe beams from conformal arrays consisting of few elements and large radius of curvature is addressed. Experimental results are presented for a 12 element array of linearly polarised elements forming a faceted array with radius of curvature 1.5 m. It is shown that by calculation of an aperture correcting matrix, sidelobe levels of 40 dB can be obtained from the array by application of conventional linear array Taylor weights. Beam steering is achieved by aperture phase tapering while low sidelobe levels are maintained     

The peak sidelobe of the phased array having randomly located elements

A formula is derived for the peak sidelobe level of a phased array in which the elements are randomly located. The parameters of the formula are the number and size of the array elements, size of the array, wavelength, beamsteering angle, and signal bandwidth. The theory is tested by measurement of the peak sidelobe of several hundred computer-simulated random arrays. Unlike the case for the conventional array the effect of spatial taper (nonuniform density of element location) upon the peak sidelobe level is minor. The peak sidelobe of the two-dimensional planar array is approximately 3 dB higher than that of the linear array of the same length and same number of elements.     

Phase-only synthesis of minimum peak sidelobe patterns for linearand planar arrays

Minimization of the maximum sidelobe level for a given array geometry by phase-only adjustment of the element excitations is considered. Optimum phases are obtained by using a numerical search procedure to minimize the expression for the pattern sidelobe level with respect to the element phases. Results for both linear and planar arrays of equispaced elements are presented. The data suggests that optimum sidelobe level is a logarithmic function of array size, and optimum patterns have relative efficiencies that are typically somewhat greater than for comparable-amplitude tapered arrays. An analytic synthesis algorithm is presented for use on very large arrays for which the numerical search technique for the minimization of the sidelobe level is computationally impractical. This method produces patterns with characteristics similar to arrays synthesized using the numerical search method, i.e. relatively uniform angular distribution of energy in the sidelobe region, and generally decreasing maximum sidelobe level as the array size is increased     

Aerial arrays with asymmetrical thinning

The use of asymmetrical element spacings in thinned aerial arrays is shown to give symmetrical radiation patterns. The use of asymmetrical element spacings gives lower sidelobe levels than symmetrical spacings. With an array of nine elements in a 19? array, the greatest sidelobe level is reduced from ?5.61 dB to ?6.87 dB by using an asymmetrical array instead of a symmetrical array.     

Reduction of sidelobes in uniformly excited arrays with element pattern control

Uniformly excited arrays of identical elements suffer from high close-in sidelobes. Suppression of sidelobe levels can be achieved by tapering the aperture amplitude distribution, but a more complex feed network results. A novel form of amplitude tapering is described, in which element pattern control in uniformly excited arrays is shown to theoretically reduce close-in sidelobe levels.     

基于遗传算法和模拟退火的不等间距稀布阵的设计

副瓣电平在天线阵列的设计中是很重要的指标,已经有很多方法进行这方面的改进。该文在稀布阵概念的基础上,引入了距离微扰,提出不等间距稀布阵的模型,来进一步改善天线阵的副瓣电平,并且利用遗传算法和模拟退火对这种不等间距稀布阵进行了综合设计。给出了200元线阵和4020面阵的优化结果,从仿真结果可以看到天线副瓣电平得到了改善。