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     

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。     

A joint field/circuit model of line-to-ring coupling structures andits application to the design of microstrip dual-mode filters and ringresonator circuits

A joint field/circuit model is proposed in this paper to characterize a class of line-to-ring coupling structures for design and optimization of microstrip dual-mode filters and ring resonator circuits. The generic model is derived from field theory and presented in terms of circuit elements by applying a newly developed numerical deembedding technique called “short-open calibration” in a deterministic method-of-moments scheme. It provides a new design strategy for characterizing and optimizing electrical performance of the line-to-ring coupling structures. Such three-port topologies are explicitly formulated by using an equivalent network having circuit elements calculated by the proposed joint field/circuit model. Three microstrip tightly coupling geometries and their related ring resonators are studied with the extracted J-inverter susceptance parameters. Experiments are performed to validate the joint model and also show coupling characteristics of the three types of line-to-ring circuit for the design of ring resonators and dual-mode filters. With this new technique, an optimized microstrip dual-mode filter is successfully designed and the prediction agrees well with our measurements     

Excitation of Waveguide by Stripline- and Microstrip-Line-Fed Slots

This paper presents investigations on coupling between stripline/microstrip line and a rectangular waveguide coupled through a slot in the ground plane which is fixed in the cross-sectional plane of the waveguide. A closed-form expression for the impedance loading on stripline/microstrip line is evaluated from knowledge of the complex power flowing down the rectangular waveguide supporting the dominant mode and discontinuity in the modal voltage in stripline/microstrip line. The reactance cancellation is obtained by terminating the stripline/microstrip tine exciting the slot in a short-circuited stub. The structure under this condition forms a transition between stripline/microstrip line and a waveguide. The design curves on slot length versus frequency are presented for different values of dielectric constants. The variation of coupling as a function of frequency and also the location of the slot is evaluated. Numerical results for slot coupling useful for the design of waveguide simulators are also presented.     

小型化高方向性的微带双定向耦合器设计

为解决弱耦合时微带平行耦合线定向耦合器方向性低的问题,提出了适用于大功率场合的小型化高方向性微带双定向耦合器。基于传统四分之一波长平行耦合三线微带双定向耦合器结构,采用扇形微带电容加载可明显减小耦合器尺寸并增大隔离度,通过耦合边缘引入锯齿结构进一步提高了方向性。负载电阻采用扇形微带短截线接地设计,避免电气化过孔,使得加工更加简单。设计了一个中心频率为915 MHz、耦合度为20 dB 的微带双定向耦合器,利用HFSS 仿真软件对耦合器结构进行优化设计,并做了实物加工和测试。实测结果表明,在中心频率处耦合度为20.2 dB,方向性达到32.1 dB;在0.74~1.35 GHz 频带内,输入匹配良好,耦合度波动小于0.5 dB,方向性高于20 dB。     

A New Microstrip Dispersion Model (Short Papers)

A new unified analysis technique is presented for dispersion in microstrip at high frequencies. The technique exploits the fact that the dispersion in microstrips is due to coupling between a surface-wave mode and the LSE mode of an appropriate model of the microstrip. The analysis uses an effective dielectric constant (EDC) approach to evaluate the mode coupling in the LSE model. Unlike previously reported models, all the parameters of the model are exactly determined from the quasistatic parameters of the microstrip, which takes the fringing field into account. Approximate closed-form equations are derived for the prediction of microstrip dispersion. The results agree within 1.50 percent with the experimental and previously published data over a wide useful range of microstrip dimensions and substrate permittivities.     

一种基于微带均衡器结构的定向耦合器的研究

提出了一种新颖的基于微带均衡器结构的宽频带高定向性微带线定向耦合器,并对该结构进行了理论分析、设计、制作和测量。该结构的新颖之处是通过对耦合度随频率的变化曲线进行均衡得到宽频带特性。该结构采用三电容补偿的微带线定向耦合器结构,并通过在耦合端集成微带均衡器结构实现。测量结果显示,该结构在2.5～3.5GHz工作频带内的耦合度随频率的变化范围约为1dB,隔离度低于-34dB,较之传统结构的微带线定向耦合器均有大幅的提高。测量结果很好地验证了设计方法的正确性。     

用于无线能量传输系统的微带天线设计

本文提出一种用于组成无线能量传输(Wireless Power Transmission,WPT)系统的微带天线结构,并采用基于有限元法的电磁仿真软件(HFSS)对微带天线进行3D建模.在二端口网络分析法的基础上,建立磁耦合共振无线能量传输等效电路模型,求解出系统发生频率分叉现象产生的条件以及最大效率时的频率表达式.基于以上方法,研究本文设计的微带天线传输特性,包括:系统的最优传输效率与耦合距离的关系,工作频率与耦合距离的关系,得出在能量传输距离在50cm左右时,天线的谐振频率为12.5MHz,效率可达63%.微带天线具有很大的结构优势,如与集成电路兼容,成本低,体积相对较小,且工艺相当成熟,易大规模批量生产等优势.因此该设计的平面微带天线可用于无线能量传输系统.     

Mutual coupling between reduced surface-wave microstrip antennas

An investigation of the mutual coupling between reduced surface-wave microstrip antennas is presented and compared with that for conventional microstrip antennas. Numerical results are presented from a theoretical analysis of the mutual coupling along with confirming experimental results. It is shown that for electrically thin substrates, the space-wave coupling, not the surface-wave coupling, is predominant for typical element spacing, for both the conventional and reduced surface-wave antennas. In addition, the mutual coupling behavior is examined using an asymptotic analysis, which demonstrates how the coupling falls off much faster with patch separation for reduced surface wave antennas compared to conventional microstrip patch antennas     

Adjustable Bandwidth Filter Design Based on Interdigital Capacitors

In this letter, we explore a general-purpose microstrip coupling model for computer aided design of new bandpass filters. The J-inverter topology of the model facilitates the study of coupling behaviours of different microstrip structures leading to a quick comparison of their coupling strengths. Based on such comparison, microstrip filters with interdigital capacitors and etched slots yielding relatively higher coupling coefficients are designed, fabricated and tested. The filters exhibit relatively wider bandwidths which are easily adjustable by way of changing the geometrical parameters of interdigital capacitors and slots.     

Wide-Band Operation of Microstrip Circulators

Octave bandwidth operation of Y-junction stripline and microstrip circulators is predicted using Bosma's Green's function analysis. The width of the coupling transmission lines is found to be a significant design parameter. Theoretical and experimental results are presented which show that wide lines and a smaller than usual disk radius can be used to obtain wide-band operation. A microstrip circulator is reported which operates from 7-15 GHz. Also presented are an analysis of the input impedance and an approximate equivalent circuit for the Y-junction circulator which shows the relationship between Bosma's equivalent circuit and that of Fay and Comstock.     

双极化口径耦合微带天线FDTD分析

本文应用时域有限差分法（FDTD）分析了双极化口径耦合多层微带贴片天线。文中结果表明,FDTD在分析多层复杂结构的微带天线时是非常有效的。采用Gauss脉冲激励,通过FFT,一次计算就可得到天线谐振频率、耦合、频带宽度、增益等参数的宽频带特性。计算结果对天线的优化设计具有一定的指导作用。     

Broad-band cavity-backed and capacitively probe-fed microstrippatch arrays

A hybrid full wave method for the analysis of probe-fed infinite phased arrays of single and stacked microstrip patches, backed by metallic cavities, is applied to investigate the combined utilization of the capacitive probe-feeding technique and the cavity enclosure of microstrip patches. The goal is to obtain broad-band microstrip antennas on thick substrates without the limitations due to the generation of surface waves of the conventional microstrip antennas on infinite substrates. A design procedure for the capacitive coupling is investigated and theoretical results for the active input impedance and radiation characteristics of different wide-band antenna designs are presented     

Theoretical and experimental investigations on microstrip active array antennas and power combiners

In this paper, microstrip active array antennas and power combiners are investigated. The mutual impedance of a rectangular microstrip patch array is analyzed based on the Richmond's reaction integral equation and Galerkin technique in spectral-domain. The computer-aided analysis and design of the active array are then carried out by coupling the mutual impedances to the large-signal characteristics of Gunn diodes with a harmonic balance technique. Based on the theoretical study, microstrip active patch array antennas are investigated experimentally.     

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     

FDTD/genetic algorithm coupling for antennas optimization

This paper introduces an original theoretical approach for microstrip antennas optimization and design. The purpose method consists in the coupling between a fdtd tool applied to the analysis of antennas and a genetic algorithm for the optimization. A neural network acting as a data base will allow to reduce strongly the computation time. This method will be illustrated on a simple example.     

Analysis of a dual circularly polarized microstrip antenna fed bycrossed slots

A dual circularly polarized, wideband microstrip antenna fed by two perpendicular crossed slots is analyzed in this work. The cross shaped aperture in the ground plane provides coupling between the microstrip patch and a single microstrip line underneath the ground plane, traversing the four arms of the cross in a serial manner, thereby generating four coupling points in phase quadratures for both senses of circular polarization. The analysis of this antenna incorporates two stages: In the first one, the individual load impedances are computed via an integral equation based on reciprocity, assuming no interactions between the ports. The second stage employs a transmission line model where the four coupling points are considered as lumped loads along the feed line. An iterative scheme employs the transmission line model for the determination of the actual impedances of each coupling point, including the mutual interactions with the other coupling points. This procedure provides control over the overall level of radiated energy; hence it can be used in the design procedure of this antenna as a serial or parallel fed array element. The computed results agree very well with measurements. The antenna attains a -3 dB gain bandwidth of 13% to 15%, a 3-dB axial ratio bandwidth of 48%, and -15 dB return loss bandwidth of 60%     

神经网络模型在耦合微带线设计中的应用

采用神经网络对耦合微带线进行建模，并将此模型应用到耦合微带线的分析与设计中。由于神经网络具有精度高，速度快等优点，因此本文建立的耦合微带线神经网络设计方法具有准确、可靠、省时、知识辅助设计等优点。文中采用该方法进行了一种耦合微带线设计，以耦合微带线的结构尺寸作为输人样本，奇偶模特性阻抗和归一化波长作为输出样本。结果证明该方法具有很高实用价值。     

Chirped delay lines in microstrip technology

In this paper, we report on a design method for chirped delay lines (CDLs) in microstrip technology. They consist in a continuously varying strip width, so that the coupling location between the quasi-TEM microstrip mode and the same but counter-propagating mode is linearly distributed in frequency. High delay×bandwidth products, over frequency ranges of several gigahertzs, can be obtained following this procedure. Experimental data confirm the design method. Real-time Fourier analysis of wideband pulses can be performed using these CDLs     

Characteristics of Coupled Microstrip Transmission Lines-I: Coupled-Mode Formulation of Inhomogeneous Lines

This paper consists of two parts. In Part I, coupled-mode theory is employed to determine the effects of reflection at the various ports and unequal inductive and capacitive coupling coefficients on the coupling and directivity of two coupled lines. Since couplers utilizing microstrip lines generally have unequal inductive and capacitive coupling coefficients, the results presented here should be useful in explaining the behavior of microstrip coupled lines. It is shown how the difference in the coupling coefficients leads to finite directivity and, under certain conditions, to "codirectional" instead of "contradirectional coupling." In Part II, the coupling coefficients and other parameters of various microstrip-line geometries are presented. Using these parameters in the results obtained here leads to an improved understanding of and design criteria for coupled microstrip lines.