Ka频段大规模相控阵稀疏布阵算法设计与应用

针对大规模卫星通信相控阵天线在阵元受发射/接收组件、驱动放大器等布局限制条件下的稀疏布阵问题,提出了一种基于极限微扰法的随机稀疏布阵算法。通过极限微扰率和随机稀疏算法的迭代应用,能够较容易地收敛到目标稀疏率下的稀疏阵列分布,且能得到均匀的稀疏布阵结果,改善相控阵天线由于局部过热导致的散热困难的问题。基于此方法,对满阵为4 096阵元的大规模相控阵天线进行了稀疏化设计,最终得到1 552阵元的稀疏阵。仿真和实测结果显示通过该算法能获得较好的阵列方向图结果,在方位角0°~360°、俯仰角0°~60°范围内副瓣均低于-16 dB。     

A Method of Cross-Polarization Reduction

A method for the reduction of cross-polarized radiation is described. The method can be used for various antenna array systems made up of radiating elements with higher cross-polarized radiation. This solution enables numerous possibilities for selecting the position, the spacing, and the excitation coefficient of any array element. It is even possible to use two different linearly polarized arrays that use the same or different polarizations. Two examples are given: a quarter-wave microstrip antenna system operating in two frequency bands, and a suspended patch array     

Phased arrays based on oscillators coupled on triangular and hexagonal lattices

Phased arrays have been proposed in which a two-dimensional array of voltage-controlled oscillators coupled to nearest neighbors provides excitations for the radiating elements which are properly phased to result in a steerable radiated beam. These arrays have been arranged on a rectangular lattice and the beam is steered by tuning the oscillators along the four edges of the array. Proposed here are similar arrays in which the oscillators are coupled on a triangular lattice or a hexagonal lattice and provide excitations for radiating elements similarly disposed in a planar triangular array. Beam steering is accomplished by tuning the oscillators along the three edges of the array. The dynamic behavior of the arrays is studied via a continuum model and the results compared with those of a full nonlinear discrete analysis and a linearized discrete model.     

Monolithically integrated HgCdTe focal plane arrays

The cost and performance of hybrid HgCdTe infrared (IR) focal plane arrays are constrained by the necessity of fabricating the detector arrays on a CdZnTe substrate. These substrates are expensive, fragile, available only in small rectangular formats, and are not a good thermal expansion match to the silicon readout integrated circuit. We discuss in this paper an IR sensor technology based on monolithically integrated IR focal plane arrays that could replace the conventional hybrid focal plane array technology. We have investigated the critical issues related to the growth of HgCdTe on Si read-out integrated circuits and the fabrication of monolithic focal plane arrays: (1) the design of Si read-out integrated circuits and focal plane array layouts; (2) the low-temperature cleaning of Si(001) wafers; (3) the growth of CdTe and HgCdTe layers on read-out integrated circuits; (4) diode creation, delineation, electrical, and interconnection; and (4) demonstration of high yield photovoltaic operation without limitation from earlier preprocessing such as substrate cleaning, molecular beam epitaxy (MBE) growth, and device fabrication. Crystallographic, optical, and electrical properties of the grown layers will be presented. Electrical properties for diodes fabricated on misoriented Si and readout integrated circuit (ROIC) substrates will be discussed. The fabrication of arrays with demonstrated I–V properties show that monolithic integration of HgCdTe-based IR focal plane arrays on Si read-out integrated circuits is feasible and could be implemented in the third generation of IR systems.     

共享孔径交错稀疏阵列天线互耦误差建模与校正

共享孔径交错稀疏阵列天线是实现多功能阵列天线的有效途径。现有的参数化互耦消除方法都是针对均匀阵列天线展开的,其研究的互耦矩阵都是规则的方阵,对共享孔径交错稀疏阵列天线的互耦矩阵模型并不适用。在充分考虑共享孔径交错稀疏阵列天线中子阵内互耦的“稀疏”和“方位依赖”的特殊性后,通过将常规的互耦矩阵扩展表示为“非方”的“增广互耦矩阵”来对交错稀疏阵列天线子阵内和子阵间的耦合效应进行建模,并通过“增广互耦矩阵”的参数化估计最终实现了共享孔径交错稀疏阵列天线互耦误差的建模与校正。仿真结果证实了所提方法的有效性和可行性。     

The nocturnal service area of MF AM broadcast stations usingvertical arrays

The nocturnal service area, or distortionless area, of MF AM broadcast stations depends on the radiation properties of the transmitting antenna and the physical constants of the ground surrounding the transmitting site. These ground constants limit the maximum antenna height and establish how large the nocturnal service area will be. In some instances the nocturnal service area can be increased by the use of vertical antenna array. In this case it is very important to know the increase of the theoretical nocturnal service area of the station and if the use of more sophisticated radiating systems is justified. Calculations were made to determine the theoretical nocturnal service area of a station using vertical arrays, and curves with maximum distortionless distance are given as a function of frequency and ground physical constants. Measurements on reduced-scale models in HF and VHF bands are described, and improvements in antenna antifading properties and in nocturnal service area are shown     

Coaxial continuous transverse stub (CTS) array

A new coaxial continuous transverse stub (CTS) array is proposed, designed, constructed, and tested. It is an omni-directional low cost antenna array which provides good impedance matching characteristics and good tolerance to manufacturing errors. It can be simply fed by a coaxial connector and is particularly suitable for millimeter wave personal communication systems (PCS). It is shown that this type of radiating element provides high percentage of radiation, and for the simulated design of single- and multiple-element arrays, S₁₁ was below -10 dB across a 6 GHz frequency span at the Ka band. A three-element prototype coaxial CTS antenna array was designed, constructed, and tested in the X-band. Experimental results were in good agreement with the simulated performance. Potential application of this new antenna array in multiband operation is also described     

SIW 耦合馈电阵列天线

提出一种新型宽带、结构紧凑的基片集成波导(SIW)背腔阵列天线的设计方法。所设计的SIW 阵列由紧密相连的背腔构成馈电网络,每个背腔上开宽缝作为辐射单元。SIW 背腔天线单元紧密排列,主要通过单元间感性耦合窗耦合馈电。SIW 背腔既是辐射单元又能实现能量分配,不需加载额外的馈电网络,因此该阵列结构十分紧凑。工作在20 GHz 频段的2×2 SIW 耦合馈电阵和4×4 SIW 耦合馈电阵已加工实现,仿真和测试结果表明所提出的SIW阵列设计方法简单、阵列结构紧凑、天线辐射性能良好。另外,本文研究了高增益大规模阵列天线的组阵方法。在2×2 SIW 耦合馈电阵的基础上,采用8×8 SIW 并联馈电网络加载天线子阵的方法设计了16×16 宽带高增益SIW 阵列天线并进行了加工测试。结果表明,采用这种组阵方法,天线阵阵元排布紧密,天线具有带宽宽、增益高、损耗低等优点。     

Extending the Field of View With Phased Array Techniques: Results of European SKA Research

The radio frequency window of the square kilometre array is planned to cover the wavelength regime from centimeters up to a few meters. For this range to be optimally covered, different antenna concepts are considered. At the lowest frequency range, up to a few gigahertz, it is expected that multibeam techniques will be used, increasing the effective field-of-view to a level that allows very efficient detailed and sensitive exploration of the complete sky. Although sparse narrow-band phased arrays are as old as radio astronomy, multioctave sparse and dense arrays now considered for the SKA require new low-noise design, signal processing, and calibration techniques. The successful implementation of these new array techniques has already been introduced for the use of phased array feeds upgrading existing telescopes: enhancing aperture efficiency as well as effective field-of-view. Especially the development of low-cost array antenna design will allow a cost-effective large-scale implementation for the SKA. This paper addresses these new capabilities, emphasizing the R&D work done in Europe and aims to provide insight into the status of enabling technologies and technical research on polarization, calibration, and side-lobe control that will unleash the potential of phased arrays for future growth of radio astronomy synthesis arrays.     

Focused Microstrip Array Antenna Using a Dolph-Chebyshev Near-Field Design

A new concept in designing large array antennas to focus the microwave power in the radiation near-field region is presented. A small focused array antenna using microstrip patch elements to achieve the desired sidelobes levels in the Fresnel region based on Dolph-Chebyshev design is implemented. This array is built to verify the concept, and then the measured and computed near fields are compared to verify the accuracy of the design. Larger arrays are designed by using the knowledge of the mutual admittances between the elements of smaller arrays. Several computed examples are presented in order to show some properties of focusing arrays. It is shown that the maximum intensity of the electric field along the axial direction is displaced from the focal point towards the antenna aperture. This displacement decreases as the aperture size increases.      

CS-DOA 估计中观测矩阵性能分析

利用压缩感知(CS)理论解决阵列信号波达方向角(DOA)估计问题,具有对快拍数据量要求低、可处理相关源等优点。CS鄄DOA 估计中的一个关键问题是构建合适的观测矩阵。文中对比分析了均匀线阵与随机稀布阵两种阵列流形的稀疏重构性能,分析结果表明在实际应用中基于随机稀布阵构建的观测矩阵性能更优。仿真实验从三个方面比较了两种观测矩阵的DOA 估计性能,验证了随机稀布阵性能的优越性,在不增加阵元数的前提下,能有效提高阵列的空间角分辨率。     

Parallel-series feed network with improved G/T performance for high-gain microstrip antenna arrays

A 16 x 8 microstrip antenna array with 28 dB of gain at 18 GHz using a parallel-series feed with reduced conductor traces is presented. The feed network connects antenna elements with about 50% reduction in conductor traces compared to conventional arrays with equal numbers of radiating elements. It also enhances the gain-bandwidth performance of the array and maintains a broadside radiation pattern in a wider frequency band. The full-wave simulation results are verified by means of measurements that demonstrate a relative gain-bandwidth of 4.4% with less than 1 dB of gain ripple.     

Impedance of an antenna-array element

A number of expressions for calculating the active impedances of the radiating elements of large linear and planar antenna arrays with allowance for the interaction of the entire set of the elements are presented. The expressions are applicable not only to the radiating elements distant from the edge of the array but also to the edge and corner elements. The expressions are based on the formulas for certain sums of elementary and higher transcendental functions that give simple closed-form expressions for the sums of mutual impedances. As an illustration, the resistances of weakly directional radiating elements in dense arrays, where the mutual coupling of the elements is extremely strong and results in important effects, are calculated.     

3英寸Si基碲镉汞分子束外延工艺研究

随着红外焦平面阵列规模的扩大,由于尺寸和成本的限制,传统晶格匹配的碲锌镉衬底逐渐成为碲镉汞红外焦平面探测器发展的瓶颈,大尺寸、低成本硅基碲镉汞材料应运而生。本文采用分子束外延工艺生长获得了3 in Si基中波碲镉汞薄膜材料,通过采用金相显微镜、傅里叶红外光谱仪、双晶X射线衍射仪、湿化学腐蚀位错密度(EPD)法、Hall测试系统等检测手段对Si基中波碲镉汞分子束外延薄膜材料进行表面、光学、结构和电学性能表征,并采用标准平面器件工艺制备中波640×512焦平面探测阵列进行材料验证,结果表明该材料性能与国际先进水平相当。     

基于阿基米德螺线的稀布面阵综合方法

提出一种基于改进遗传算法的稀布面阵综合的新方法。该方法通过对阿基米德螺线参数的合理设置,确保了阵元在沿阿基米德螺线的轨迹分布时依然能够满足阵元数约束、孔径约束和最小阵元间距约束,从而将稀布面阵的优化问题转化为非对称线性阵列的稀布问题,这就大大降低了问题的复杂程度。仿真实验结果证明了该方法的有效性。     

基于改进遗传算法的天波超视距雷达二维阵列稀疏优化设计

针对均匀矩形平面阵在2维阵天波超视距雷达(OTHR)工程应用时阵元数目庞大问题,该文提出利用改进遗传算法进行稀疏优化设计的解决办法。从波束赋形角度出发建立了稀疏矩形平面阵的布阵优化模型;以俯仰波束能分辨OTHR多模传播的波达角(DOA)为原则确定了遗传算法的初始种群;为避免遗传进化中出现早熟和随机漫游现象修正了适应度函数;为实现稀疏率精确控制改进了交叉和变异算子。仿真结果表明,该文算法不仅实现了稀疏率的精确控制,同时提高了优化性能。该文最后对2维稀疏阵列在OTHR工程应用时的可行性进行了分析,指出其应用条件和存在的技术难点,并给出了相应的解决方案。     

基于虚拟阵列的二维稀疏阵列相干源DOA估计

波达方向DOA估计是雷达阵列信号处理的一个重要方向,传统的MUSIC算法对均匀阵列条件下独立信号源的估计有很强的适应性,但实际的雷达工作中,稀疏布阵下多相干源测角是一个经常出现的应用场景。文中针对二维稀疏阵列的相干源测角,提出了一种基于虚拟阵列的相干源DOA估计方法。该方法利用虚拟阵列内插的方法,将一个任意二维稀疏阵列内插为一个均匀面阵,再通过二维空间平滑方法对相干源进行测角,能够同时获得信号的方位角和俯仰角信息。稀疏面阵和稀疏圆阵的仿真实验结果表明,该方法可以有效的解决二维稀疏阵列的相干源测角问题。     

Infinite planar arrays of arbitrarily bent thin wire radiators

A plane wave expansion moment method is presented for computing active impedances and current distributions of infinite planar arrays of thin wire radiating elements. The array lattices can be rectangular or triangular. The excitations can be plane waves or progressively phased voltage sources. Each radiating element, including feedline, can be any collection of bent thin wires. Results are given for arrays of straight dipoles with straight feedlines, straight dipoles with bent feedlines, and swept back dipoles (arms inclined with respect to the array planes) with straight feedlines. The experimentally observed phenomenon of array blindness as a consequence of feedline scattering is verified theoretically. The absence of this effect when the dipole arms are inclined with respect to the array plane also is verified.     

Analysis of infinite arrays of microstrip-fed dipoles printed onprotruding dielectric substrates and covered with a dielectric radome

A method for analyzing infinite arrays of antennas printed on both sides of substrates protruding from a ground plane and covered with a dielectric radome is described. Using the equivalence principle, the array unit cell is decomposed into homogeneous regions where the fields are expressed as Floquet summations, and an inhomogeneous cavity region where the fields can be found by a combination of the method of moments and modal analysis. The approach is rigorous in the sense that the combined effects of the radiating element and feed geometry printed on opposite sides of a protruding substrate are taken into account. The method is quite general, capable of modeling any antenna elements with substrate currents that are perpendicular and/or parallel to the ground plane. In addition, both the radiating and scattering/receiving modes of operation are treated in the analysis. The method is used to calculate the active element impedance of an infinite array of dipoles transmission line-coupled to microstrip feeds. Examples of numerical results are presented for various scan conditions and the effects of a near-field dielectric radome are demonstrated     

Center feed single layer slotted waveguide array

A center feed configuration is newly introduced to enhance the bandwidth as well as to suppress the frequency dependent beam squinting in single layer slotted waveguide arrays. A multiple-way power divider consisting of cross-junctions is installed at the center of the aperture in an alternating-phase fed waveguide slot array to reduce the long line effect in the radiating waveguide. Each radiating slot is equipped with an inductive wall for reflection canceling, which dispenses with the beam tilting technique for suppressing cumulative reflection and assures the boresight beam. All these are equipped in single layer and are potential for low cost mass-production as is usual the case with alternating phase-fed arrays. The test antenna is fabricated at 26GHz band for FWA system. A 30.5 dBi gain with 46% efficiency with the main beam staying in the boresight is obtained. The sidelobes of -9.5 dB associated with the aperture blockage for the center feed is suppressed to below -14.7 dB at the design frequency, by applying a genetic algorithm for controlling the slot excitation.