V频段圆柱龙伯透镜天线设计

设计并实现了一种V频段圆柱龙伯透镜天线.在平行平板波导间,根据龙伯透镜原理与介电常数等效原理,推导出了圆柱龙伯透镜天线的理论设计公式,并结合商业仿真软件高频结构仿真器(HFSS)仿真分析和优化,完成天线设计.仿真结果表明,该V频段圆柱龙伯透镜天线增益为21.4 dBi,波束宽度为1.56o,副瓣电平为-14.7 dB.根据设计结果,加工和测试验证V频段圆柱龙伯透镜天线的可实现性,实测结果表明,该天线增益为20.1 dBi,波束宽度为1.60o,副瓣电平为-11.1 dB,天线效率为45.7％,说明该天线具有一定的工程应用价值.     

龙伯透镜天线的原理及其研究进展

龙伯透镜天线是一种折射率渐变的透镜天线,可将特定频率的入射波汇聚到透镜表面的某点或将电磁波沿原方向反射,能够实现波束扫描和多波束聚焦,已用于电子对抗、第五代移动通信技术、卫星通信以及军用战机和舰艇.介绍了龙伯透镜天线的基础理论,归纳梳理了球形龙伯透镜天线和变形龙伯透镜天线,总结了三种制备技术,对比了不同类型的透镜天线性能,并分析了馈源对龙伯透镜性能的影响,最后对龙伯透镜天线的发展提出建议.     

用矢量球面波理论和互易原理分析伦伯透镜天线

伦伯透镜是一种球形分层介质天线,考虑到数值计算的复杂性,本文提出用矢量球面波理论和互易原理相结合,分析其性能。该方法首先用矢量球面波理论计算平面波入射到多层介质球的散射场,在此基础上,用互易原理将散射场转变成天线的远区辐射场。基于这种方法,本文着重研究了伦伯透镜天线的焦区场和远区场特性,包括透镜分层总数以及层与层之间存在的空气间隙对实际应用可能造成的影响。最后,对卫星通信中伦伯透镜天线多波束应用的可行性给出了分析结果。     

Permittivity of composites used for Luneburg lens antennas by drilling holes based on 3-D printing technique

Due to the attractive performances such as the ability of beam focus, broadband, multi-beam scanning and other features, Luneburg lens antennas are applied in multi-beam antenna, which overcomes the problem of gain loss produced by multi-beam parabolic antenna. Based on 3-D printing technique, Luneburg lens antennas by drilling holes are studied. Permittivity and loss tangent of the equivalent lens materials can be influenced by original materials, hole shapes, hole directions, and porosity. After tests, polystyrene with waxes may be the most appropriate materials for Luneburg lens with high strength. Permittivity with the shape of triangle is the lowest due to the homogeneity. Relative permittivities with the direction at a range of 15°-45° are lower while loss tangent at a range of 0°-30°. Radial directional holes are more appropriate for Luneburg lens. The relative permittivity is decreased with the increment of porosity. After calculations, the forecasts calculated by Looyenga and A-BG theory are more precise. Finally, Luneburg lens with two layers is fabricated by 3-D printing.     

基于光学变换的平面龙伯透镜天线

龙伯透镜天线具有高增益、低副瓣和宽带特性,可以实现多波束,进行大角度扫描等优点,主要应用于卫星通信、电子对抗等领域。但因其体积大、重量大和球形结构不易固定等缺点,在实际应用中受到很大的限制。本文基于光学变换原理设计了一种新型的全介质平面龙伯透镜天线,半径为60 mm,厚度为20 mm,在15 GHz时,天线增益为23 dB,半功率波束宽度为12°,第一副瓣电平低于-23 dB。同时设计了平面和圆弧馈源阵列,在70°范围内实现了较好的多波束覆盖。     

Design Optimization of Multishell Luneburg Lenses

Guidelines are provided for designing multishell Luneburg lenses (LL) whatever the primary source is. Three different optimization problems that minimize three different norms of the discrepancy between the ideal relative permittivity and the reconstructed one with respect to the thickness and permittivity of each shell are detailed. The performances of the three so-optimized LL are compared by simulations with those of previously proposed approaches. The highest directivity is obtained for the minmax norm. An investigation of the influence of the number of shells on the lens antenna performances, directivity, sidelobe levels and aperture efficiencies for various lens diameters, is also proposed in order to better know how to choose these parameters. Finally, measurements done with a multishell Luneburg lens fed by a waveguide are compared with simulations to show, through excellent agreements between theory and measurements, the validity of this study     

Design of Multibeam Dielectric Lens Antennas by Multiobjective Optimization

We propose an effective method for designing multibeam dielectric lens antennas. A genetic algorithm (GA) with multiobjective optimization is adopted to balance gain against sidelobe level. The lens shapes and the position of each feed are associated with chromosomes. The gain and sidelobe level are evaluated by a pareto ranking method. The method yields the distribution of the objective function values and the corresponding antenna structures.      

介质加盖高增益微带天线的优化

本文提出了利用点源增益优化方法设计介质加盖的高增益微带天线的方法,所确定的各介质层的电厚度能保证天线取得最高的增益。同时优化计算量也成倍减少。所设计的一个两层介质加盖微带天线的最高增益达到16.8dB。分析结果还表明,在一定条件下,增益和效率是可以兼顾的,用加盖的方法提高天线增益的同时仍可使天线具有较高的辐射效率。     

Radiation characteristics of uniform and nonuniform dielectricleaky-wave antennas

An approach based on a waveguide model for analyzing the uniform and nonuniform dielectric leaky-wave structures is proposed for which the Galerkin solution method is applied. In the first part of the paper the far-field radiation of the uniform antenna is determined theoretically and experimentally in the Ku band and also the dependence of beamwidth and sidelobe level as function of strip width and frequency is demonstrated. In addition, an analysis of the antenna with a tapered-strip distribution-is presented. The second part describes a novel tapering procedure, performed by changing the width of the uniform antenna, for obtaining the radiation pattern with lower sidelobe levels. Sinusoidally and exponentially shaped dielectric leaky-wave structures are analyzed as nonuniform antennas. Finally, the radiation and scanning characteristics of these antennas are theoretically presented     

Optimum Design of Millimeter-Wave Double-Dielectric Fresnel Zone-Plate Lens and Antenna

The microwave/millimeter-wave Fresnel-zone plate (FZP) lenses differ substantially in construction, technology and applications from their optical analogs and require specific design equations and methods of electromagnetic analysis. In this paper, optimum design equations for double-dielectric lossless FZP lens are derived. The best and worst choices of the permittivity ratio for lossless dielectrics are discussed in detail. In addition, the influence of dielectric losses on the lens thickness for given wavelength and permittivities is examined. Two versions of a 57.5-GHz double-dielectric phase-reversal zone plate are used as focusing elements of FZP lens antenna. The antenna co-polar and cross-polar radiation patterns, aperture efficiency and frequency bandwidth are analyzed numerically and contrasted with those of half-blocked FZP and horn lens antennas.     

Compound Fresnel Zone Lens Conformal to Truncated Cone: Antenna Application

A millimeter wave antenna consisting of two Fresnel zone plate lenses, plane and conical, is examined numerically by use of the vector diffraction theory. The lenses are of Wood-Wiltse (double-dielectric) or Soret (half-open) type, and are designed for the frequency of 117 GHz. The lenses are made conformal to a truncated circular cone with a base diameter of 500 mm and a plateau diameter of 250 mm. Designs for two opening semi-angles, 45° and 75° each of them with a particular lens thickness are presented. For the angle of 90° the cone lens becomes a plane ring lens, which in combination with the plateau zone lens forms a plane lens of size equal to the cone base diameter. Illuminated by directive feeds set at a focal distance of 525 mm from the cone apex, the double-dielectric and half-open compound and plane lenses, form three pairs of Fresnel zone lens antennas, the co-polar and cross-polar radiation characteristics of which have been compared numerically. The double-dielectric lens antennas examined are about 5 dB superior in gain to the half-open lens antennas, which has a gain of approximately 45 dBi. Because all lenses are of equal transverse aperture, the corresponding lens antennas exhibit the same ?3 dB beamwidth of about 0.33 degrees. The plane zone lens antenna is very thin and simple. Instead, the antenna comprising a 3-D compound Fresnel zone lens is thicker but can be made conformal to a specific surface shape and possesses more levels of design and optimization freedom.     

Design procedure for a Fresnel-zone plate antenna

A design procedure for two types of Fresnel-zone plate antennas is presented: viz. antennas with absorbing/transparent zones and phase-correcting zones. Design objectives are the optimization of the gain of the lens of the antenna and the side-lobe envelope of its radiation pattern. The design rules are derived from numerical simulations.     

The design of radially symmetric lenses

For scanning over wide angles at millimeter wavelengths, an antenna incorporating a radially symmetric lens is an attractive solution if the lens can be realized in a practical form. It is shown that suitable lenses can be constructed very simply, from natural dielectrics if desired, and a design technique for the optimal antenna is presented. Some results are given of analytical and experimental studies of a number of actual antennas operating at wavelengths near 4 mm. These confirm that practical solutions are available. Homogeneous lenses may be used up to antenna gains of about 35 dB, and a lens consisting of a single shell and a core is sufficient for most other practical requirements.     

An electromagnetic analysis of a cylindrical homogeneous lens

Radially symmetric lenses are ideally suited for use as multiple-beam antennas. In recent years, several investigations using a geometrical optics approach have indicated that simple lens structures such as homogeneous lenses might be suitable antennas. This paper presents an electromagnetic analysis of a cylindrical homogeneous lens as well as examining in detail the effect upon performance of parameter variations such that engineering and design evaluations can be made. It is shown that a lens with a relative dielectric constant of 3.5 gives the best performance. With the use of simple matching techniques, overall performance comparable to the more complex Luneburg lens is obtained.     

基于新型泡沫材料的龙伯透镜天线设计

该文利用新型泡沫材料聚甲基丙烯酰亚胺(PMI),设计了一种适用于复杂太空环境探测的毫米波龙伯透镜天线,通过将泡沫材料的密度与介电常数相关联,结合传统龙伯透镜天线的工作原理进行仿真优化,实现了小型化高增益多波束的功能。仿真结果表明：该天线工作于33.7 GHz,增益可以达到25.65 dBi,波束宽度4.17°。该设计方法为将来小型化高增益的龙伯透镜的实现提供了新的思路。     

Broadband active microstrip antenna design with the simplified realfrequency technique

This paper deals with the design of broadband active microstrip antennas where the amplifier is integrated with the radiator. Theoretically sound definitions for gain and noise figure of the active antenna are introduced, and their relationships with the definitions for the composing circuit and radiator parts are explained. A sequential design procedure is presented that allows the straightforward and optimal design of transmitting and receiving antennas with multiple active stages, taking into account input and output matching, the gain-versus-frequency curve as well as the noise performance. The theoretical concepts are illustrated with two examples: one of a transmitting active antenna and one of a receiving antenna. The former one is a two-stage design that achieves nearly 25% of bandwidth with regard to gain and matching and 24 dB gain improvement as compared to the matched passive antenna. The second one is a receiving antenna (one stage) with a measured noise figure of 1.2 dB in a bandwidth of over 17% and a gain improvement of 11.9 dB over the corresponding passive antenna. Finally co- and cross-polar radiation patterns in E- and H-plane prove that the antennas also have favorable radiation characteristics in a wide bandwidth (at least 18%)     

分层伦伯透镜天线的辐射性能计算

介绍了伦伯透镜及伦伯透镜天线的特点，用经典电磁理论模式展开法计算平面波入射分层伦伯透镜时的散射场，然后利用此结论和互易定理计算喇叭天线作为馈源时伦伯透镜天线的辐射场。     

Nature-Based Design of Aperiodic Linear Arrays with Broadband Elements Using a Combination of Rapid Neural-Network Estimation Techniques and Genetic Algorithms

The developments presented in this paper address the challenge of determining the optimal element positions in nonuniformly spaced broadband phased-array antennas in order to best meet desired performance criteria. Specifically, this is accomplished by introducing a new nature-based design technique that couples a robust genetic-algorithm (GA) optimizer with rapid neural-network (NN) estimation procedures. These provide performance criteria as functions of the element positions over the entire scanning range and bandwidth of operation. The objective of this GA-NN technique is to determine the optimal element positions for a broadband aperiodic linear phased-array antenna in order to minimize element VSWRs and sidelobe levels. The NN estimation procedures circumvent the need for computationally intensive full-wave numerical simulations during the optimization process, which would ordinarily render such an optimization task impractical. The effectiveness of the new GA-NN design synthesis technique is demonstrated by considering an example where a nonuniformly spaced linear phased array of ten stacked patch antennas is optimized for operation within a given bandwidth and scanning range.     

Wire-antenna designs using genetic algorithms

There is a large class of electromagnetic radiators designated as wire antennas. As a rule, an inductive process is used to design these antennas. Either an integral equation is formulated or a simulator is used that gives the current distributions on the wires of the antenna, from which the electromagnetic properties of the antenna can then be determined. Once the antenna properties are known, the parameters are optimized, using guides such as intuition, experience, simplified equations, or empirical studies. However, using an electromagnetics simulator in conjunction with a genetic algorithm (GA), it is possible to design an antenna using a completely deductive approach: the desired electromagnetic properties of the antenna are specified, and the wire configuration that most closely produces these results is then synthesized by the algorithm. In this paper, we describe four antennas designed using GAs. The first is a monopole, loaded with a modified folded dipole that was designed to radiate uniform power over the hemisphere at a frequency of 1.6 GHz. The second antenna consists of seven wires, the locations and lengths of which are determined by the GA alone, that radiates waves with right-hand-circular polarization at elevation angles above 10°, also at 1.6 GHz. The last two antennas are modified Yagis. One is designed for a broad frequency band and very low sidelobes at a center frequency of 235 MHz. The other is designed for high gain at a single frequency of 432 MHz. We have built and tested these antennas     

Parallel particle swarm optimization and finite- difference time-domain (PSO/FDTD) algorithm for multiband and wide-band patch antenna designs

This paper presents a novel evolutionary optimization methodology for multiband and wide-band patch antenna designs. The particle swarm optimization (PSO) and the finite-difference time-domain (FDTD) are combined to achieve the optimum antenna satisfying a certain design criterion. The antenna geometric parameters are extracted to be optimized by PSO, and a fitness function is evaluated by FDTD simulations to represent the performance of each candidate design. The optimization process is implemented on parallel clusters to reduce the computational time introduced by full-wave analysis. Two examples are investigated in the paper: first, the design of rectangular patch antennas is presented as a test of the parallel PSO/FDTD algorithm. The optimizer is then applied to design E-shaped patch antennas. It is observed that by using different fitness functions, both dual-frequency and wide-band antennas with desired performance are obtained by the optimization. The optimized E-shaped patch antennas are analyzed, fabricated, and measured to validate the robustness of the algorithm. The measured less than - 18 dB return loss (for dual-frequency antenna) and 30.5% bandwidth (for wide-band antenna) exhibit the prospect of the parallel PSO/FDTD algorithm in practical patch antenna designs.