基于遗传算法的深空探测天线综合

为了改善深空探测中共焦面阵列馈电抛物反射面天线的可视范围,提出一种基于遗传算法的扫描波束综合方法。基于物理光学法计算共焦面馈电阵中每个馈源照射反射面的次级远场方向图,利用遗传算法优化得到的权值对各次级方向图加权合成期望的波束。仿真和分析结果表明：提出的基于遗传算法的共焦面阵列馈电反射面方向图综合与传统共轭场匹配方法相比,可控制旁瓣电平,更精确综合出期望方向图,扩大深空探测天线的可视范围。     

Bees algorithm for design of dual‐beam linear antenna arrays with digital attenuators and digital phase shifters

This article describes a method of designing a reconfigurable dual‐beam linear antenna array using bees algorithm (BA). The BA is an optimization algorithm inspired by the behavior of the honey bees to find the optimal way of harvesting food resources around the hive. The proposed method is very simple and can be used directly in practice to synthesize multiple beam antenna arrays with digital attenuators and digital phase shifters. A good agreement between the desired pattern and the synthesized pattern using BA is obtained. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

基于遗传算法的多板天线时延相位补偿技术

关于动中通系统中普遍采用抛物面天线,可使得系统小型化难度增加,为优化最佳天线方案,采用平板天线取代抛物面天线可以部分改善.为促进动中通技术在车载平台中的应用,提出了超低轮廓相控阵天线方案,使得平板相控阵天线的高度进一步降低.针对孔径效应和孔径渡越时间限制问题,给出了时延相位两级补偿的方法,有效扩展了天线系统的工作带宽;同时采用遗传算法调整天线阵因子相位,对多板相控阵天线方向图的副瓣高度实现了优化.仿真结果表明,多板天线方案可以实现性能对平板天线的逼近,并很好的适应了车载平台对天线高度的严格要求,有较高的工程实用价值.     

用于卫星通信的Ku波段宽带双频双极化微带天线阵

利用口径耦合馈电、错位倒相馈网技术和单层微带贴片结构设计出一种用于卫星通信的Ku波段宽带双频双极化微带四元天线阵。用电磁仿真软件CST2008对天线阵的电特性进行了仿真和优化。四元天线阵实测结果表明:水平极化端口在11.21GHz～13.47GHz频率范围内VSWR燮1.5,相对阻抗带宽为18.3%;垂直极化端口在13.43GHz～14.88GHz频率范围内VSWR燮1.5,相对阻抗带宽为10.24%。工作频带内两端口隔离度<-35dB,最大增益为13.2dB,与仿真结果一致。     

基于蜂群算法任意平面阵最大信干噪比研究

针对复杂战场环境下超短波电台天线接收低信噪比信号能力弱和易受定向干扰的缺陷,结合战场超短波电台不规则分布和位置不能任意改变的特点,提出任意结构天线阵信号接收模型,采用蜂群算法优化阵元相位使得天线阵输出信干噪比最大。假设信噪比为0 dB,干噪比为60 dB,且在平面内随机选取8个阵元,采用蜂群算法优化后输出信干噪比为8.633 dB。与改进差分进化算法、遗传算法和粒子群优化算法相比,分别提高了0.577 dB、1.124 dB和1.543 dB。研究成果可为超短波电台组阵通信提供参考。     

A novel suspended stripline‐fed printed square slot array antenna with high‐gain

A novel suspended stripline‐fed square slot array antenna with high gain is presented. Its basic structure is a suspended stripline comprising of three layers. On the top layer, 4 × 4 square slots are etched and act as radiation elements. The middle layer consists of a suspended stripline power divider, and the bottom layer is a metal ground. After optimization by a parallel Genetic Algorithm (GA) on a cluster system, a prototype antenna is fabricated and tested. The measured results agree well with the simulated data, and show a high gain of 18.7 dBi and an impedance bandwidth of 5.7% for S11<‐10 dB are obtained. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

High frequency integrated feed for front end circuitry and antenna arrays

Low‐cost printed circuit board waveguide (PCBWG) technology is employed to develop new waveguide‐fed microstrip antenna arrays with low profile and light weight while maintaining high efficiency and gain at 12.5 GHz. The proposed corporate feed network has two parts: on the antenna layer, microstrip lines are used to form a 2 × 4 sequentially rotated sub‐array of circularly polarized microstrip patches and on the feed layer PCB‐WG is utilized to combine any number of these sub‐arrays to form a larger array. Because PCB‐WGs transmit the power over a large portion of the feed network, losses are substantially reduced and spurious radiations from feed circuit are eliminated. Several microstrip arrays with PCBWG feed were designed and fabricated using standard PCB process. Comparing the results with those of a hybrid array with conventional waveguide feed shows that there is only a negligible degradation in gain and efficiency when bulky and expensive aluminum waveguides are replaced by PCB‐WGs. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Pattern synthesis for opportunistic array radar using least square fitness estimation‐genetic algorithm method

Pattern synthesis in three‐dimensional (3D) opportunistic array radar becomes complex when a multitude of antennas are considered to be randomly distributed in a 3D space. To obtain an optimal pattern, several freedoms must be constrained. A new pattern synthesis approach based on the improved genetic algorithm (GA) using the least square fitness estimation (LSFE) method is proposed. Parameters optimized by this method include antenna locations, stimulus states, and phase weights. The new algorithm demonstrates that the fitness variation tendency of GA can be effectively predicted after several “eras” by the LSFE method. It is shown that by comparing the variation of LSFE curve slope, the GA operator can be adaptively modified to avoid premature convergence of the algorithm. The validity of the algorithm is verified using computer implementation. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A new class of harmonic components for millimeter‐wave applications

This article presents several new harmonic components for millimeter‐wave applications. These components include a commonly used patch antenna and a bandpass filter operating at 35 GHz. The components have the advantages of easier fabrication and feeding compared with the commonly used traditional components operating at fundamental frequencies. The harmonic components are also used to build an antenna array. Good performance is obtained from these harmonic components in comparison with the traditional components. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Design of aperiodic planar arrays for isoflux radiation in GEO satellites by applying evolutionary optimization

The design of an aperiodic planar array is presented in this research. This design of aperiodic arrays considers the reduction of the side lobe level and the isoflux radiation requirements for GEO (Geostationary Earth Orbit) satellite applications. In this way, it is considered four different optimization cases. The first two cases are optimizations of amplitude and phase excitations for the antenna elements in a uniform antenna array and the last two cases are optimizations of positions of the antenna elements and certain number of levels of amplitude excitation in an aperiodic array. In this case, it is proposed a simple new approach combining the main idea of both thinned theory and random arrays approaches. For this optimization problem, the well-known method of Genetic Algorithms (GA) is utilized. The obtained results show the proper performance of the array factor to provide the isoflux radiation and low side lobe level. Depending on the performance requirements, the design of the aperiodic array could lead the satellite hardware to be reduced significantly even more that results presented previously in the literature.     

An extended particle swarm optimization algorithm for pattern synthesis of conformal phased arrays

In this article, an extended particle swarm optimization (EPSO) algorithm is proposed for designing conformal phased arrays. On the basis of traditional particle swarm optimization (PSO), novel velocity updating mechanism, new exceeding boundary control operator, and global best perturbation are introduced in EPSO to overcome the drawbacks of PSO. To validate the efficiency of the proposed algorithm, both the classical test functions and the scenarios concerning a 1 × 9‐element cylindrical conformal phased array and a 3 × 9(27)‐element cylindrical conformal array with flat‐top shaped‐beam pattern are presented. Simulation results show that the proposed method is superior to genetic algorithm (GA) and PSO when applied to both the classical test functions and the practical problems of conformal antenna array synthesis. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

MIMO‐UWB smart antenna communication characteristics for different antenna arrays of transmitters

The channel capacity of indoor multiple‐input multiple‐output ultra‐wide band (MIMO‐UWB) transmission for smart antenna is presented. The genetic algorithm (GA) is used to synthesize the radiation pattern of the directional antenna array to maximize the capacity performance in indoor MIMO‐UWB communication system. Three types of antenna arrays such as circular shape, L shape and Y shape arrays are used in the transmitter and their corresponding capacity on several paths in the indoor environment are calculated. The UWB impulse responses of the indoor channel for any transmitter‐receiver location are computed by applying shooting and bouncing ray/image (SBR/image) techniques, inverse fast Fourier transform and Hermitian processing. By using the calculated frequency response, the capacity performance of the synthesized antenna pattern on MIMO‐UWB system can be computed. Based on the topography of the antenna array and the capacity formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the GA algorithm. The GA algorithm optimization is applied to a high order nonlinear optimization problem. The novelties of our approach is not only choosing capacity as the cost function instead of sidelobe level of the antenna pattern, but also considering the antenna feed length effect of each array element. The cost function for the problem is nonsmooth and discontinuous with respect to the antenna pattern. It is difficult to solve by gradient methods, since the derivative is hard to derive. The GA algorithm is employed to optimize the excitation voltages and feed lengths for these antenna arrays to increase the capacity. The strong point of the GA is that it can find out the solution even if the performance index cannot be formulated by simple equations. Numerical results show that the synthesized antenna array pattern is effective to focus maximum gain to the LOS path for these antenna arrays. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the capacity can be increased substantially in indoor MIMO‐UWB communication system. The investigated results can help communication engineers improve their planning and design of indoor wireless communication. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

A nonuniform array of slots in the broad‐walls of rectangular waveguides partially filled with dielectric slabs

This article describes a new nonuniform slot antenna array in the broad wall of rectangular waveguides partially filled with a dielectric slab. The slot elements are nonuniformly spaced to achieve a higher side lobe level while the amplitude and phase of their excitations are identical. Each slot element is fed by one dielectric‐loaded rectangular waveguide with one end shorted for structural simplicity. Experimental results for an 8‐element linear slot array operating at X‐band show that the side lobe level is 15 dB over a frequency range from 9.5 GHz to 10.5 GHz. The simulated side lobe level can reach 20 dB for a 16‐element linear array. Experimental results show that the side lobe level of a slot array can be improved using nonuniform element spacing without degrading the broadside radiation and gain. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Amplitude‐only pattern nulling of linear antenna arrays with the use of an immune algorithm

This article presents an optimization immune algorithm (opt‐IA) for null steering of linear antenna arrays by controlling only the element amplitudes. Nulling of the pattern is also achieved by controlling the phase‐only and the complex weights (both the amplitude and phase) of the array elements. The opt‐IA is a new evolutionary computing algorithm based on the clonal selection principle of immune system. To show the accuracy and flexibility of the proposed opt‐IA, several examples of Chebyshev array pattern with the imposed single, multiple, and broad nulls are given. It is found that the nulling technique based on opt‐IA is capable of steering the array nulls precisely to the undesired interference directions. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

CSRR based folded monopole tri‐band antenna array and its system level evaluation

In this article, a folded monopole antenna loaded with complementary split ring resonators (CSRRs) is proposed for tri‐band applications. The two bands of the antenna are generated by the folding of the monopole (first band is caused due to fundamental mode and another due to higher order mode) and CSRRs have been responsible for the third band. By using four such antennas in form of an array, the gain and bandwidth have been improved. The prototype of the antenna array is developed on FR4 substrate and simulated results are experimentally validated. A simplified equivalent circuit model of the antenna has been developed and analyzed to quantify the power loss due to input impedance mismatch at each resonance frequency. By using the EM model of the proposed antenna in the Keysight ADS verification test bench its suitability to operate in the system environment has been confirmed.     

有源相控阵天线测试通用平台设计与实现

有源相控阵天线在完成装配之后要进行功能和性能测试,整个过程繁琐、复杂,并且不同架构的天线有不同的测试方法,现阶段天线测试系统多属于定制化研制。针对不同架构天线,提出通用化、标准化的测试硬件和构件化、模块化的软件平台,并基于某型雷达天线做了应用验证。结果表明天线测试通用平台相比于传统测试平台,测试精度基本一致,系统集成速度提升69%,软件复用率提升50%,开发人员能够快速、准确集成天线测试系统,使用人员能够使用标准天线测试流程提升测试效率,对有源相控雷达的研制具有重要意义。     

Broadband T‐bar fed slot antenna array with stable horizontally polarized omnidirectional radiation

A broadband horizontally polarized omnidirectional antenna array is proposed, which consists of a circular array of four identical broadband T‐bar fed cavity‐backed slot antenna elements and a 1‐to‐4 power divider. The proposed omnidirectional antenna array has a compact diameter of only 0.44λ₀, a broad bandwidth of 75.9% (450‐1000 MHz) and a favorable omnidirectional radiation pattern in the azimuth plane with a gain variation below 3 dB in the operating band. Moreover, the cavity‐backed structure makes the proposed antenna array hardly affected by metal environment and the all metal construction allows for high‐power applications, and the reserved cable channel behind the cavities of the antenna elements ensures the extensionality and stability of the proposed array when longitudinal array expansion is needed. Design procedures of the proposed antenna array have been described in detail, simulations and measurements of the proposed antenna array have also been carried out to validate its performance in this article.     

A dual‐feed microstrip grid array antenna for balanced or unbalanced operation

The development of a dual‐feed microstrip grid array antenna for either balanced or unbalanced operation to radiate pencil‐beam patterns has been described. As an example, the dual‐feed microstrip grid array antenna on RT/duroid 5880 substrate with a size of 60 × 60 × 0.787 mm³ or 4.8λ × 4.8λ × 0.063λ at 24 GHz were designed and fabricated. The measured results show that the dual‐feed microstrip grid array antenna has achieved excellent performances: 4.85% impedance bandwidth, 9.03% gain bandwidth, and 20.6‐dBi gain at 24.15 GHz as a balanced antenna and 6.05% impedance bandwidth, 7.74% gain bandwidth, and 17.8‐dBi gain at 24.15 GHz as an unbalanced antenna. The dual‐feed microstrip grid array antenna is a suitable antenna candidate for radar and sensor applications.     

数字化相控阵天线测试方法及测试系统设计

伴随着雷达技术的飞速发展,数字化相控阵天线开始广泛运用于各种相控阵雷达当中;由于数字化相控阵天线的工作原理与传统模拟相控阵天线差异极大,测试方法也发生了根本性的改变,原有的基于普通微波仪表的天线测试系统无法再对数字化相控阵天线进行测试,必须设计新型的数字化相控阵天线测试系统;文章首先介绍了数字化相控阵天线自身的工作原理和测试方法,随后提出了新型数字化相控阵天线测试系统的具体软硬件设计方案,实际应用表明数字化相控阵天线测试系统可以满足各种数字化相控阵天线的测试要求。     

射频自动阻抗匹配的分层遗传算法实现

阻抗匹配问题在射频技术中有着极其重要的意义,良好的阻抗匹配不仅有利于电路的低压低耗实现,而且较小的反射系数为系统的可靠运行提供了保证。针对遗传算法在自动阻抗匹配过程中收敛速度慢且易陷入早熟（即陷入局部最优）,提出利用分层机制来预防早熟,并对遗传算法中的交叉操作算子进行了改进来加快收敛。通过MATLAB对上述算法进行实现,并采用不同频率及不同负载阻抗对上述算法及遗传算法进行测试从而进行比较。结果表明分层遗传算法很好地预防了早熟,收敛速度比原算法得到较大的提升。