A generalized method for the evaluation of mutual coupling in microstrip arrays

An analytical method for the evaluation of mutual coupling in microstrip arrays is discussed. The elements of the array are excited by microstriplines printed on or embedded in the substrate. As an example, the mutual coupling between microstrip dipoles electromagnetically coupled to embedded strip transmission lines is evaluated accurately. The presented method is valid in the millimeter range as weft as at microwave frequencies and does not have any substrate limitations. Also, it accounts for conductor thickness and surface wave excitation. Comparison with experimental results shows excellent agreement.     

A moment-method design procedure for an array of EMC dipoles

A design procedure based on a moment-method analysis is given for an array of microstrip dipoles electromagnetically coupled (EMC) to microstrip transmission lines. One of the key features of the design procedure is that only one pair of EMC dipoles needs to be analyzed at a time in order to develop the necessary coupling coefficients. These coupling coefficients allow for the complete analysis or design of the array, accounting for interactions between all of the EMC line-dipole pairs. One of the useful properties of the present formulation is that EMC dipole arrays can easily be designed for which the length and offset of each dipole are the same, which simplifies the array construction     

The design of microstrip dipole arrays including mutual coupling, part II: Experiment

Experiments are described from which determination can be made of the self and mutual impedance for microstrip dipoles and of the backscattering relation involving the radiating current. Functional representations of these sources of input data then permits the design of planar microstrip dipole arrays, including the effects of mutual coupling. The design, construction, and performance of a typical array are described. Agreement between theory and experiment is good.     

An asymptotic closed-form microstrip surface Green's function forthe efficient moment method analysis of mutual coupling in microstripantennas

A relatively simple closed-form asymptotic representation for the single-layer microstrip dyadic surface Green's function is developed. The large parameter in this asymptotic development is proportional to the lateral separation between the source and field points along the air-dielectric interface. This asymptotic solution remains surprisingly accurate even for very small (a few tenths of a free-space wavelength) lateral separation of the source and field points. Thus, using the present asymptotic approximation of the Green's function can lead to a very efficient moment method (MM) solution for the currents on an array of microstrip antenna patches and feed lines. Numerical results based on the efficient MM analysis using the present closed-form asymptotic approximation to the microstrip surface Green's function are given for the mutual coupling between a pair of printed dipoles on a single-layer grounded dielectric slab. The accuracy of the latter calculation is confirmed by comparison with numerical results based on a MM analysis which employs an exact integral representation for the microstrip Green's function     

Multiport network approach for modeling the mutual coupling effectsin microstrip patch antennas and arrays

A method is described for representing the mutual coupling between edges of a microstrip patch (or the edges of two different patches in an array) in form of a mutual admittance matrix. Coefficients of the mutual admittance matrix are evaluated by modelling the edge fields by equivalent magnetic current line sources. The formulation is an extension of the multiport network modeling of microstrip patches and the segmentation method of analysis. Results are found to be in good agreement with the measured data on mutual coupling available in the literature. Relative contributions of various edges of rectangular patches to the mutual coupling are discussed     

Analysis of a microstrip array and feed network

An analysis technique for a microstrip array is presented. The array elements and mutual coupling between elements are analyzed by a method of moments (MM) solution of the exact integral equation. The combination of the microstrip array elements, plus the microstrip transmission line feed network is analyzed using a generalized Thévenin theorem. The method is applied to the specific problem of the series fed microstrip array.     

Corporate feed design for microstrip arrays

A design technique for an embedded microstrip corporate feed is presented. The aim of the design is to shape each corporate feed junction to achieve a tapered and in-phase output current distribution. From this, a Dolph-Chebyshev array sum pattern may be constructed. In the experiments, the designed corporate feed is used to excite a five-element equispaced linear array of overlay microstrip dipoles. It is found both theoretically and experimentally that a 20-dB Dolph-Chebyshev broadside sum pattern can be synthesized in the H-plane at 8.5 GHz. Mutual coupling among the dipoles is included in this analysis. The pattern degradation due to manufacturing tolerances on the alignment between the feed network and the dipole array is discussed     

Synthesis of linear arrays of series fed proximity-coupled microstrip antennas

This paper presents a synthesis of linear standingwave arrays of microstrip antennas such as transverse dipoles, series-fed by a proximity coupled microstrip line. Each radiating element is characterized by its self-admittance and mutual coupling admittance. The self-admittance depends on geometrical parameters and on the nature of the substrate, while the mutual coupling admittance is related to the presence of the other radiating elements. These values are computed exactly using an integral equation technique combined with a two-port model of the element. The synthesis procedure is validated with measurements of the radiation pattern and a return loss of a 20-dipole array. The importance of mutual coupling in the design process is clearly demonstrated.     

Mutual impedance computation between printed dipoles

The mutual impedance between microstrip dipoles printed on a grounded substrate is computed. Results for the microstrip dipoles in broadside, collinear, and echelon arrangements are presented. The significance of surface waves to mutual coupling is discussed.     

应用于交通信息检测雷达的阵列天线设计

介绍了一种应用于交通信息检测中多普勒雷达前端的K波段64阵元微带双天线,该天线采用并联形式馈电,通过对天线互耦的分析,电抗补偿和减小耦合等方面的改进,满足了天线性能和尺寸等实际应用的需求。双天线衬底背面固定集成雷达收发前端和中频信号处理电路。经过对天线和整个系统前端的测试表明:天线在工作频点,回波损耗低于-20dB,最大增益为25.2dB,E面、H面半功率波瓣宽度为8.1°和6.3°,其仿真和测试结果较好吻合。整个雷达前端在实际外场测试中检测准确灵敏,并在实际智能交通系统工程中得到了很好的应用。     

Scanning characteristics of infinite arrays of printed antennasubarrays

The analysis and scanning characteristics of several different types of infinite arrays composed of subarrayed printed dipole and microstrip patch elements are presented. The analysis is based on full-wave moment method theory, and includes mutual coupling between elements in the subarray as well as between subarrays. The effect of subarraying on scan blindness is demonstrated for arrays using two-element subarrays of printed dipoles and microstrip patches. Results are also given for the amount of power radiated in grating lobes. The effect of a subarray composed of one driven element and one parasitic element, and the use of a four-element synchronous subarray of microstrip patches to generate circular polarization are also considered. Data are given for impedance mismatch, power radiated into grating lobes, and the axial ratio; both square and rectangular patches area considered. Results are also shown for an infinite array of seven-element hexagonal subarrays of printed dipoles, and it is found that the large spacing between subarrays leads to a limited scan range     

互耦影响下的自适应圆阵分析

本文用矩量法严格分析了考虑互耦影响时自适应天线阵元的电流分布,给出了计算电流的解析式,并计算了八单元圆阵的电流分布。用等效网络法推导了考虑互耦影响时的最佳权矢量。仿真计算了不同阵元间距时,自适应阵的数字波束赋形。     

Microstrip linear slot array antenna for X-band

The X-band microstrip slot antenna array is described as an attempt to achieve moderate bandwidth and overcome the problems of radiation from microstrip feed lines and surface waves in the dielectric. The discussion covers development of a mathematical simulation that computes the radiation pattern of a single microstrip slot and the feeding microstripline; construction of a uniform broadband microstrip slot antenna array; development of a mathematical simulation that computes the radiation pattern in the H- and E-planes; and investigation of the mutual coupling between the slots. A comparison is made between computed and measured results at X-band frequencies     

基于小间距低耦合阵元的微带天线阵设计*

设计微带天线阵时,减小阵元间距会导致阵元间耦合增加,从而导致增益下降(在考虑口径增益减小的基础上进一步下降).针对该问题,提出一种减弱小间距阵元间耦合的新方法,即通过在地板上蚀刻两条共面波导,引入新的幅度可调的耦合去抵消原有耦合,从而实现减小阵元间耦合的目的.该方法将邻边间距为0.024λ0(λ0是自由波长,中心间距约0.38λ0)的阵元之间的隔离度(IS21I)从6.1dB提高到21dB以上,改善了阵元的辐射特性,使每个阵元的辐射方向图接近单个贴片的辐射方向图.为验证有效性,本文基于该方法设计了一副二元微带天线阵,并对其进行测试,与等口径面的二元阵比较,增益提高了约1.2dBi,与等增益的二元阵比较,面积减少了约10.2％,且副瓣电平有较大改善.     

利用混合模型法计算微带天线间互耦

基于微带天线的传输线模型和空腔模型，提出了一种计算微带天线间互耦的新方法。在本方法中，首先根据腔模法原理，将微带天线等效为相距半波导波长的两个辐射缝隙；然后分别利用微带天线的传输线模型以及微带天线边缘面上的等效磁流分布求出微带天线的自阻抗和互阻抗，并进一步计算微带天线间的耦合系数。最后，利用本文方法编写Matlab程序求解矩形微带天线间的互耦，并与实验进行对比，比较结果验证了方法的高效性和可靠性。     

Analysis of finite arrays of axially directed printed dipoles on electrically large circular cylinders

Various arrays consisting of finite number of printed dipoles on electrically large dielectric coated circular cylinders are investigated using a hybrid method of moments/Green's function technique in the spatial domain. This is basically an "element by element" approach in which the mutual coupling between dipoles through space as well as surface waves is incorporated. The efficiency of the method comes from the computation of the Green's function, where three types of spatial domain Green's function representations are used interchangeably, based on their computational efficiency and regions where they remain accurate. Numerical results are presented in the form of array current distributions, active reflection coefficient and far-field pattern to indicate the efficiency and accuracy of the method. Furthermore, these results are compared with similar results obtained from finite arrays of printed dipoles on grounded planar dielectric slabs. It is shown that planar approximations, except for small separations, can not be used due to the mutual coupling between the array elements. Consequently, basic performance metrics of printed dipole arrays on coated cylinders show significant discrepancies when compared to their planar counterparts.     

一种毫米波一维单脉冲圆极化微带天线的研究

本文设计了一种毫米波双魔T 结构的单脉冲右旋圆极化微带阵列天线。针对微带天线经典“H”形馈电类型在单 元间距较小时不再适用的问题,设计混合馈电网络以减小馈线与贴片单元的互耦,并在天线背面采用双魔T 结构的波 导和差网络馈电。这种结构设计在一定程度上减小了馈电插入损耗。为减小平行长馈线间耦合,采用了在两级馈电网 络间加隔离贴片的方法,有效地隔离了平行馈线间的耦合,消除部分表面波影响,保证了功率分配。仿真结果与实测 结果吻合较好。     

一种宽频带微带贴片天线阵设计

本文在微带天线阵列设计中，采用孔径耦合馈电的办法，将辐射贴片层和馈电网络分层设计，可以获得令人满意的阻抗带宽。实测表明阵列相对带宽可达 20%以上，并且这种馈电方式避免了两者共面时由于尺寸限制，馈电网络难于设计的缺点，减小了互耦及交叉极化，是大型微带贴片天线阵列的一种理想结构形式。     

利用点源阵模型分析微带贴片天线

提出了一种新的微带贴片天线远场分析模型.与传统的等效磁流分析方法不同,通过对贴片天线表面电流的合理假设,利用点源阵及波瓣图乘法原理,将微带天线看作半波阵子的连续阵来分析,求得了其辐射场.将结果与其他模型的结果进行了比较,证明了该方法的有效性.     

Dielectric cover effect on rectangular microstrip antenna array

A theoretical model to analyze a covered rectangular antenna with an arbitrary dielectric constant superstrate is developed. The antenna is simulated by the radiation of two magnetic dipoles located at the radiating edges of the patch. The Green's function of an elementary magnetic dipole in a superstrate-substrate structure, utilizing spectral-domain analysis, is formulated, and the surface-wave and radiation field are computed. An improved transmission line model, which considers the stored energy near the radiating edges and the external mutual coupling, is used to compute the input impedances and radiation efficiency. Design considerations on the superstrate thickness and its dielectric constant are discussed. Experimental data for a single element and a 4×4 microstrip array is presented to validate the theory