Phased array theory and technology

This review of array antennas highlights those elements of theory and hardware that are a part of the present rapid technological growth. The growth and change in array antennas include increased emphasis on "special-purpose" array techniques such as conformal and printed circuit arrays, wide angle scanning arrays, techniques for limited sector coverage, and antennas with dramatically increased pattern control features such as low sidelobe, adaptively controlled patterns. These new topics have substantially replaced large radar arrays in the literature and constitute a major change in the technology. The paper presents a tutorial review of theoretical developments emphasizing techniques appropriate to finite arrays, but indicating parallel developments in infinite array theory, which has become the useful tool for analysis of large arrays. A brief review of the theory of ideal arrays is followed by a generalized formulation of array theory including mutual coupling effects, and is appropriate to finite or infinite arrays of arbitrary wire elements or apertures in the presence of a conducting ground screen. Some results of array tolerance theory are summarized from the literature and retained as reference throughout discussions of array component requirements and device tolerance for low sidelobe arrays. Examples from present technology include conformal and hemispherical coverage arrays, lightweight printed circuit arrays, systems for use with reflectors and lenses in limited sector coverage applications, and wide-band array techniques.     

Fabrication and performance of an InP/InGaAsP monolithic 12 × 12-element matrixed LED array

The fabrication of a large-area InP/InGaAsP double-heterostructure LED monolithic matrixed array of 144 light-emitting elements is presented. Each LED produces ?2.5 mW at an operating current of 150mA with per-element bandwidths of ?200 Mbit/s. The array, which we believe to be the largest integrated optoelectronic circuit fabricated in this material system, is thus capable of very high power output and bandwidth. Such arrays are expected to be useful in many optical data link applications.     

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.     

微热板阵列的热干扰

针对微热板阵列建立了热路模型,并对热干扰进行分析.结果表明,由于微热板悬窄结构的热阻比硅芯片的热阻高3个数量级.因此微热板阵列芯片的热干扰温度取决于封装对环境的热阻,而芯片上器件的间距对热干扰温度的影响可以忽略.研制了3种布局、T05和DIPl6两种封装形式的微热板阵列,并对阵列中的热干扰问题进行了实验测试.测试数据验证了热路模型的结论.因此,减小微热板阵列或集成芯片的热干扰的关键在于,尽可能增大微热板悬空结构的热阻以及选用热阻小的封装形式.     

Cavity backed microstrip patch array feed for multiple beamapplications

Multiple beam antennas use reflectors with several feeds at offset locations in the focal plane. The complete feed array tends to be bulky and heavy, hence, to alleviate this, microstrip patch arrays have been used as feed elements. However, a power division circuit becomes necessary for the patches which increases losses. A patch array backed by a cylindrical cavity is proposed which eliminates this lossy circuit. An additional feature is that the beamwidths in various planes may be controlled to a certain extent by varying the interelement spacing. The test results of the proposed feed are presented and discussed; the feed seems suitable for use in multiple-beam applications     

Self-phasing antenna array techniques for mobile communicationsapplications

This paper provides a summary of the basic concepts of retrodirective antenna arrays. Originally this class of antenna was developed in the 1960s for direct satellite-to-ground transmission of high-power microwave energy. The explosive growth of mobile communications has, in the authors' opinion, reopened the debate for alternative applications of retrodirective array techniques. Advances in microstrip antenna design coupled with the availability of integrated circuit amplifier and mixer components permit minimum-complexity retrodirective antenna arrays to be constructed. Several different planar retrodirective antenna architectures are presented and their basic operational characteristics given. A novel application for co-operating retrodirective antennas in a duplex communication link with inherent space division multiple access capability is also described. Finally some of the operational parameters which could ultimately limit the performance of this class of antenna are discussed     

Phased array systems in silicon

Phased array systems, a special case of MIMO systems, take advantage of spatial directivity and array gain to increase spectral efficiency. Implementing a phased array system at high frequency in a commercial silicon process technology presents several challenges. This article focuses on the architectural and circuit-level trade-offs involved in the design of the first silicon-based fully integrated phased array system operating at 24 GHz. The details of some of the important circuit building blocks are also discussed. The measured results demonstrate the feasibility of using integrated phased arrays for wireless communication and vehicular radar applications at 24 GHz.     

A Generalized Approach to a Solution of Aperiodic Arrays and Modulated Surfaces

A generalized approach to a solution of the aperiodic phased-array problem, and derived periodically modulated surfaces, is possible by an extension, using linear superposition, of the solutions for the related periodic phased array. This approach can be applied to any aperiodic array of elements such as planar arrays of waveguides, or dipoles, or thick walled parallel-plate arrays. It also leads to the solution for the dispersion relation, in terms of the periodic phased-array solution, for the surface of short-circuited waveguide clements; the short circuit depth being periodically modulated along the surface.     

Construction of thinned phased antenna arrays by coding the positions of array elements in a equidistant grid of nodes on the basis of the properties of prime and composite number moduli

A method for construction of thinned phased antenna arrays (PAAs) by coding the positions of array elements in an equidistant grid of nodes on the basis of the properties of prime and composite number moduli is proposed. (Such arrays are abbreviated as PAA-C.) An algorithm for the arrangement of array elements is described, examples of the arrangement of elements are presented, and the array patterns and their cross sections are calculated. A method for suppression of sidelobes of the PAA-C pattern is proposed. The method is based on the multiplication of the patterns of PAA-Cs differing in their codes corresponding to one modulus or in coding by twin prime numbers.     

Mutual coupling between metal strip antennas on finite size,electrically thick dielectric substrates

An analysis of the mutual coupling between metal strip antennas which are contiguous with the ends of finite-size, electrically thick dielectric substrates is outlined. Such antennas have been proposed as useful monolithic microwave integrated circuit antennas for millimeter-wavelength applications. The analysis presented was verified experimentally, and the results are applied to three-element arrays of metal strip folded dipoles with coplanar strip feed lines. The effect of the electrically thick, finite-size dielectric substrates on the mutual coupling between elements of the arrays is described     

Metal Halide Perovskite Arrays: From Construction to Optoelectronic Applications

Inorganic semiconductor arrays revolutionize many areas of electronics, optoelectronics with the properties of multifunctionality and large-scale integration. Metal halide perovskites are emerging as candidates for next-generation optoelectronic devices due to their excellent optoelectronic properties, ease of processing, and compatibility with flexible substrates. To date, a series of patterning technologies have been applied to perovskites to realize array configurations and nano/microstructured surfaces to further improve device performances. Herein, various construction methods for perovskite crystal or thin film arrays are summarized. The optoelectronic applications of the perovskite arrays are also discussed, in particular, for photodetectors, light-emitting diodes, lasers, and nanogratings.     

Photosensing Arrays with Improved Spatial Resolution

The spatial resolution obtainable in a photosensing array used for optical imaging may be limited by the diffusion of photogenerated carriers within a uniformly doped semiconductor even if other components of the optical system are optimized and scattered light is reduced. A technique has been developed to improve the spatial resolution for critical applications by incorporating subsurface electric fields that accelerate the photogenerated carriers toward or away from the surface so that the carriers are prevented from diffusing to distant photosensing elements. The subsurface fields are obtained by incorporating suitable dopant concentration gradients into the structure. In one structure fabricated the subsurface field was formed by using a heavily doped buried layer and a lightly doped epitaxial film over a lightly doped substrate, all of the same conductivity type. This structure is compatible with the incorporation of other semiconductor devices in the same monolithic substrate. The technique has been applied to an array of photodiodes in a silicon integrated circuit, but the principle is directly applicable to other types of photosensing arrays, such as charge-coupled devices (CCD's), and other semiconductor materials.     

A frequency-controlled beam-steering array with mixing frequency compensation for multichannel applications

A frequency-controlled beam-steering planar array with mixing frequency compensation is presented for cost-effective multichannel phased array applications. The new feed networks for frequency compensation not only operate in wide band but also ensure radio-frequency (RF) amplitude imbalance cancellation and progressive phase distribution. The parallel equal power dividers installed in both LO and intermediate-frequency (IF) feed networks provide uniform amplitude and phase distribution, while the fixed delay lines installed in the LO feed network exhibit precise phase progression, compared to a series feed structure. The LO power imbalance caused by the unequal delay line loss between elements is corrected by pumping each mixer into the LO saturation region, leading to linear IF-RF response. Thus, sidelobe degradation and pattern distortion caused by the RF amplitude imbalance, as well as the beam-steering error and beam squint caused by the phase errors of the delay lines, are removed. The proposed feed networks combined with quasi-Yagi antenna arrays and microwave monolithic integrated circuit mixers realize a broad bandwidth of more than 3 GHz in K band for multichannel wireless applications. The K band transmitter/receiver pair proposed in this paper successfully demonstrates two-channel simultaneous RF transmission and single channel 50-Mb/s data communication with 40/spl deg/ scanning. This simple, compact, yet cost-effective planar array ensures multichannel broadband wireless communications with beam-steering capability.     

Complex 3D CMOS circuits based on a triple-decker cell

Presents circuit design for a three-dimensional (3D) CMOS integrated process. This process, with its three stacked transistor channels, leads to the very efficient basic circuits: inverter, selector, and NAND2. These elements are used to build a complete cell library with standard elements like NORs, latches, flip-flops, etc. Special macro blocks such as multipliers, SRAMs and content addressable memories (CAMs) complete the circuit library. Novel concepts and implementations of three-dimensional prefabricated semicustom arrays are introduced. These are the NAND array and the selector array, for which technology-dependent logic synthesis is investigated. Area requirements for static 3-D CMOS logic ranges from 50% down to 33% compared to two-dimensional (2-D) CMOS. These figures include the wiring and are caused by the transistor stacking and the large number of interconnection layers used in the 3D CMOS process.<>     

Photosensing arrays with improved spatial resolution

The spatial resolution obtainable in a photosensing array used for optical imaging may be limited by the diffusion of photogenerated carriers within a uniformly doped semiconductor even if other components of the optical system are optimized and scattered light is reduced. A technique has been developed to improve the spatial resolution for critical applications by incorporating subsurface electric fields that accelerate the photogenerated carriers toward or away from the surface so that the carriers are prevented from diffusing to distant photosensing elements. The subsurface fields are obtained by incorporating suitable dopant concentration gradients into the structure. In one structure fabricated the subsurface field was formed by using a heavily doped buried layer and a lightly doped epitaxial film over a lightly doped substrate, all of the same conductivity type. This structure is compatible with the incorporation of other semiconductor devices in the same monolithic substrate. The technique has been applied to an array of photodiodes in a silicon integrated circuit, but the principle is directly applicable to other types of photosensing arrays, such as charge-coupled devices (CCD's), and other semiconductor materials.     

CCD arrays for readout of electrophotographic latent images

Arrays of charge sensing elements have been fabricated for nondestructive electronic readout of latent images on electrophotographic materials. The arrays are implemented in the form of a monolithic integrated circuit in which each sensing element is a 5-μm ×5-μm MOS capacitor; 2048 such elements are arranged in a linear format with effective 5-μm element-to-element pitch. On-chip circuitry allows for multiple sampling at each sensing site for enhancing signal-to-noise ratio. The resulting signals from the sense elements are multiplexed onto charge-coupled-device (CCD) shift registers for high-speed serial readout. To allow for the small sensor-to-film gap (on the order of 10 μm) required for capacitive sensing, the chip's bond pads are recessed in deep grooves below the active array surface. The array is packaged within a hydrostatic air bearing which maintains a constant and uniform gap. The response of the array to targets of high spatial frequency recorded on various electrophotographic materials is in excellent agreement with analytical predictions     

Printed circuit antennas with integrated FET detectors formillimeter-wave quasi optics

Planar twin dipole microstrip antennas with integrated FET detectors which provide antenna patterns suitable for millimeter-wave quasioptical applications are discussed. The circuits are suitable for use as individual elements of an imaging array. A 63-GHz heterodyne mixer using such a circuit produced a system noise temperature of 7900 K     

Analysis of infinite arrays of substrate-supported metal stripantennas

An electric field integral equation method is applied to a metal strip antenna on an electrically thick dielectric substrate of finite size in a uniform infinite array environment. An efficient solution is found using the method of moments. Metal strip folded dipole antennas are analyzed both with and without a coplanar strip feed line, and the effects of the substrate and feed line are investigated. A technique for minimizing the effect of feed line scattering is presented, and arrays of these elements are shown to be capable of good scanning performance over a wide range of beam-steer angles. A phased array simulator experiment is described and the measured results show good agreement with those obtained by analysis. The class of antenna elements studied may be fabricated using monolithic microwave integrated circuit (MMIC) technology, and the analysis described illustrates the expected characteristics for millimeter-wavelength phased arrays of this type     

双极化方形微带天线的阻抗特性

在方形微带贴片的相邻两边电可以辐射双极化波。文中结合平面电路技术,腔模理论,用Ｇｒｅｅｎ函数法导出了双边馈电方形微带天线输入阻抗与互阻抗的计算公式,分析了Ｘ波段双极化方形贴片天线输入阻抗,Ｓ参数和电压驻波比在谐振频率附近的变化情况,以及馈电点位置与宽度和εｒ对这些特性参数的影响。文中的计算方法可靠而简捷,可用于此类天线的设计,这种天线容易形成阵列结构,并易于有源集成。