同轴馈电微带天线输入阻抗的高效精确计算

提出了一种高效精确计算同轴馈电微带天线输入阻抗的方法.采用等效磁流环模型模拟同轴馈电,通过深入研究该馈电模型的激励电场,提出一种改进的数值积分路径以避开激励电场中的奇异点,在此基础上,对贴片在线面连接处作细化处理来模拟连接处剧烈变化的电流,结合分层介质格林函数,采用空域矩量法计算了方形和圆形同轴馈电微带天线的输入阻抗.计算结果与仿真软件结果吻合较好,证明了该方法的正确性.

     

蝶形微带天线的全波分析与宽带设计

介绍了蝶形微带贴片天线的一种全波分析方法－矩量法,与多端网络法相比,其适应范围更广。然后介绍了展宽天线频带的一种设计方法。通过不对称馈电方式,激励起两个相近频率的模式,从而使微带天线驻波比带宽获得明显展宽。测试结果与计算结果相当吻合,证实了数值分析与设计方法的有效性。     

Design of wide-band aperture-stacked patch microstrip antennas

A variation of the aperture-coupled stacked patch microstrip antenna is presented, which greatly enhances its bandwidth. Bandwidths of up to one octave have been achieved. The impedance behavior of this antenna is compared with that of other wide-band microstrip radiators. Matching techniques for the antenna are presented and their relative merits discussed. The effects of varying several key physical parameters of the antenna are investigated, lending some insight into its wide-band operation. Variations on the design such as incorporation of additional patches are also discussed     

Directly coupled multiple resonator wide-band microstrip antennas

Three new configurations for increasing the impedance bandwidth of the microstrip patch antennas are described. In these configurations, additional resonators are directly coupled through short sections of microstrip line to the radiating edges, nonradiating edges, and all the four edges of the rectangular patch antennas, respectively. Green's function approach and segmentation method are used for the analysis. The experimental results are in reasonable agreement with the analysis and impedance bandwidths of 548 MHz, 605 MHz, and 810 MHz are obtained for these three configurations, respectively inS-band (substrate thickness = 0.318 cm andepsilon_{r} = 2.55). The variation in the radiation pattern over this impedance bandwidth is discussed.     

Full-wave analysis of cavity-backed and probe-fed microstrip patcharrays by a hybrid mode-matching generalized scattering matrix andfinite-element method

A full-wave method to analyze probe-fed infinite phased arrays of arbitrarily shaped microstrip patches residing in a cavity is proposed. The method is based on a combination of the mode matching and finite-element methods (MM-FEM) and provides a rigorous characterization of the coaxial feed. The radiated field to the half space is expressed as a Floquet's harmonic expansion reducing the analysis to a single elementary cell of the periodic antenna. The unit cell is analyzed as an open-ended succession of homogeneous waveguides of diverse cross sections. Each transition between waveguides is solved by a hybrid MM-FEM procedure to obtain its generalized scattering matrix (GSM). Finally, the GSM of the structure, which characterizes the array, is obtained from the individual GSMs by a cascading process. The method is also extended to the analysis of conventional probe-fed microstrip arrays by using the waveguide simulator model. Several prototypes, implemented and measured in a waveguide simulator, have been analyzed to prove the validity and efficiency of the proposed method     

Full-wave analysis of antennas containing horizontal and vertical metallizations embedded in planar multilayered media

The paper presents an efficient way of evaluating Green's functions arising in planar stratified media. In the spectral domain, the components are split into a singular and a regular part. The latter is expressed in terms of exactly four boundary coefficients, whose computation is extracted from the numerical kernel of the method, and the former is evaluated analytically via the Sommerfeld identity. The spatial counterparts are then evaluated by a method which combines the advantages of the complex image method (CIM) and the direct numerical evaluation of the Sommerfeld integral, while trying to avoid their respective drawbacks. The result is an efficient technique to treat horizontal and vertical metallizations embedded in multilayered media. Results for a three-dimensional (3D) planar inverted "F" antenna are obtained with this technique and successfully compared to measurements.     

一种宽频带圆柱共形微带天线全波分析和设计

采用双层介质双贴片结构展宽天线的阻抗带宽,并利用小的贴片电容补偿由厚介质衬底引起的探针电感效应,进一步扩展了频带宽度.基于共形FDTD法结合圆柱分层媒质中并矢格林函数的新方法,对此类天线的近场和远场特性进行了严格的全波分析.提出了系统的设计流程,使得天线的设计过程变得简单易行.设计和仿真结果表明,在不增加剖面厚度的情况下,工作于L和C波段的天线带宽(VSWR≤2.0)可达近30%甚至更宽.     

A numerical model for multilayered microstrip phased-array antennas

A numerical model is presented to analyze multilayered microstrip infinite phased-array antennas. The model is based on modular approach where each layer is considered as a module characterized by its generalized scattering matrix. The individual scattering matrices are combined in appropriate sequence to yield the overall scattering matrix and the impedance matrix of the structure. Accuracy of the model is verified by comparison with available measured and computed results. The major advantages of the model are outlined in the conclusion     

Full-wave analysis of microstrip floating-line discontinuities

A full-wave analysis of the resonance generated by a floating line is presented. Beginning with the dyadic Green's function for a dielectric slab, an integral equation is formulated. This integral equation is then solved by the method of moments in obtaining the transmission and reflection coefficients, as well as current distributions along the transmission line and on the floating line, both longitudinal and transverse. Employing these results, the near- and far-zone fields, as well as radiation patterns are computed. It was found that under resonance conditions the radiation power can exceed 13% of the feeding power, which may cause a potential problem in electromagnetic compatibility. Singularities involved in the Sommerfeld integrals are carried out by a novel pole extraction technique in conjunction with conventional folding methods. The new technique reduced the relative error of the singular integrals due to inaccurate pole position about one order in magnitude in comparison to the traditional approaches. To verify the new approach, a number of cases of open-ended transmission lines and gap discontinuities are examined. The results obtained from this method showed good agreement with those of previous publications     

管道内微带天线的FDTD全波分析与设计

针对金属管道中探测作业无缆机器人微波供能系统,对其能量接收部分的接收天线进行了设计, 采用时域有限差分法(FDTD)结合PML边界条件全波分析了管道内圆极化微带天线,数值结果与测试结果比较吻合,验证了此数值算法的有效性.     

Full-wave analysis of aperture-coupled microstrip lines

Two methods are presented for the analysis of aperture-coupled microstrip lines. Assuming a quasi-transverse electromagnetic traveling wave incident on the feeding line, an expression for the wave on the coupled line is derived. First, the moment method is used and the current on the coupled line is represented by a traveling wave propagating away from the slot. In the second method, the reciprocity theorem is applied to the coupled line. Both the moment method and the reciprocity method make use of the exact Green functions and produce results that are in very close agreement. An equivalent circuit is derived and the S-parameters are computed. Theoretical results are verified with measurements     

角馈微带天线的全波分析

利用积分方程法对角馈型微带天线进行了分析,对其中的奇异振荡函数积分,给出了有效的数值积分方法。数值实验证明了该方法的有效性。同时,给出了角馈微带天线的输入阻抗特性,方向图特性和带宽特性。     

Rigorous analysis of probe-fed printed annular ring antennas

This paper presents calculated and measured results for the input impedance and radiation performance of probe-fed printed annular ring antennas. Geometries featuring stacked rings as well as shorting posts are considered. A numerical model is presented that is based on a full-wave spectral-domain moment-method solution. In this solution, a specialized attachment mode-expansion function is used to model the connection between the probe feed and the printed ring. Measured results are presented and compare well with the theory. Annular rings are found to have certain advantages over circular and rectangular microstrip antennas     

Efficient method for analysis and design of aperture-coupledrectangular microstrip antennas

A method for the analysis and design of rectangular microstrip antennas coupled through a small aperture to a microstrip feed line in a two-layer configuration is described. The technique is numerically efficient, making it suitable for computer-aided design. The analysis takes into account higher order modes excited underneath the patch. Analysis results were implemented in two computer programs: an analysis program and a design program based on optimization techniques. Experimental results are presented to validate this method     

On the use of wide-band, high-gain, microstrip antennas for mobiletelephones

The increasing use of cellular telephones has spawned considerable research effort on the design of compact, high-efficiency antennas for mobile telephones, exhibiting low EM coupling to the human head. Microstrip antennas seem now to render possible the achievement of all these characteristics. We present some results on a stacked microstrip antenna designed at the University of Utah, comparing its performance with that of a typical handset equipped with the conventional monopole antenna. The main thrust is to highlight the problems associated with typical mobile-telephone antennas, and to show how microstrip-antenna technology could solve most of these problems     

Full-wave spectral analysis and design of annular patch antenna with electromagnetically coupled microstrip feed line

This paper presents a full-wave analysis, and the ensuing design considerations, of the annular patch antenna fed by an electromagnetically coupled microstrip line. The numerical analysis employs the spectral domain version of the integral equation, with the method of moments formulation; the basis functions on the ring patch are the eigenmodes of the corresponding magnetic wall cavity, and subsectional (rooftop) functions are employed on the access line. Both TM and TE modes are used, along with more-efficient "collective" solenoidal modes; mode sorting criteria are given to ensure uniform convergence. Efficient schemes are presented for the calculation of the spectral-domain reaction integrals, along with criteria to avoid calculation of negligible mode-to-mode couplings, based on the spectral analysis of the matrix condition number. Very good agreement is shown with measured data, and design considerations are given for matching the radiator.     

Some convergence considerations in space-domain moment-methodanalysis of a class of wide-band microstrip antennas

The method of moments (MoM) analysis of probe-fed rectangular microstrip patches requires the inclusion of a probe-to-patch attachment mode-expansion function when the substrate thickness d⩾0.02λ, where λ is the free-space wavelength. The results for the input impedance showed increased divergence with measurements when the attachment mode was omitted from the full-wave analysis. The attachment mode can be expressed as an infinite eigenfunction series that increases the fill time of the impedance matrix in an MoM analysis. In an earlier investigation, the infinite eigenfunction series was reduced to a residue series that required one or two terms compared to about 55 terms for the eigenfunction series. In this paper, the convergence properties of the eigenfunction and residue series are investigated in view of rigorous MoM analysis. The relative errors resulting from replacing the eigenfunction by the residue series for the attachment mode, are compared by numerically evaluating a class of two-dimensional (2-D) spatial integrals shown to be closely related to the elements of an MoM impedance matrix. Additionally, the computation times for the evaluation of these integrals for the two forms of the attachment mode-expansion function are also included. Based on the superior convergence properties of the residue series for the attachment mode-expansion function, it is mathematically justified that this form can readily be used for analytic reduction of the spatial, reaction integrals from four to 2-D forms. This feature allows further reduction of the fill time of the MoM impedance matrix, suggesting the possibility of developing an efficient space-domain MoM technique for modeling of wide-band microstrip antennas     

Full-wave analysis of radiation effect of microstrip transmission lines

A full-wave analysis of radiation effects produced by discontinuities in microstrip and buried microstrip transmission lines is presented. Beginning with the dyadic Green's function for a dielectric slab, with an embedded source, an integral equation is formulated. This equation is then solved by the method of moments to obtain the current distributions along the transmission line, in particular, near the discontinuities. Employing these results, the near- and far-zone fields, as well as radiation patterns are computed. The results from our method showed good agreement with those of previous publications in complex reflection and transmission coefficients, and equivalent capacitance values. It is found that under resonance conditions the radiation efficiency of a simple structure can exceed 41%, which may cause a potential problem in electromagnetic compatibility. Our analytic result also shows that the maximum radiation occurs when the source is located at the height of from the bottom ground plane, which should be prevented.     

Phased arrays of probe-fed stacked microstrip patches

This paper presents calculated and measured results for infinite phased arrays of probe-fed stacked rectangular and circular microstrip patches. A numerical model is described that is based on a rigorous Green's function/Galerkin solution. In this solution, the connection of one or more vertical probe feeds to each patch is accurately modeled using a special attachment mode basis function, which is derived from the corresponding cavity model solution. Numerical results for both linearly and circularly polarized arrays are obtained. Measured results from a waveguide simulator are also presented and used to validate the numerical model     

Analysis of a probe-fed short-circuited microstrip antenna

The input impedance of a probe-fed short-circuited microstrip antenna (SCMSA) is presented. The electric field expression under the microstrip patch by using the Wiener-Hopf technique is used and the electromotive force (EMF) method is applied. Analytical and experimental results for the impedance show the dependence on the dimensions and frequency