Performance of DRA with different pumping schemes based on coupling equation

After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.The counter-pumping scheme will induce higher ASE.And the co-pumping DRA has greater DRB noise,but its NF and OSNR are both better than the others’.Furthermore,the relations between signal power and NG,NF,OSNR are also investigated.It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power.The above conclusions can play a very important role in guiding the optimum design of DRA.     

Signal bandwidth consideration of mutual coupling effects on adaptive array performance

The effect of mutual coupling on the performance of a least mean square (LMS) adaptive array using dipole elements is analyzed in consideration of the signal bandwidth. The purpose here is to illustrate quantitatively the significance of the effect of mutual coupling. The results show that the effect in the broad-band signal cases is much greater than that in the narrow-band cases, particularly when few antenna elements are used.     

Analysis of injection-locked antenna array including mutual coupling effects

In this paper, the injection locking performance analysis of dipole antenna array with each element loaded with a two-terminal oscillator is presented. The analysis is based on the nonlinear model of oscillator and the linear model of antenna array considering mutual coupling effects. The locking range of injection signal and the array radiated power are obtained by solving an equivalent multiport network. In general, the solutions include stable and unstable solutions. The Routh-Hurwitz stability criterion is then applied to remove the unstable solutions. Numerical results show that the array performance such as frequency locking range and radiated power by taking into account the array mutual coupling effects is quite different from that of an isolated antenna element. In addition, the influence of antenna element spacing upon array locking parameters in this paper is found to be consistent with other existing theories.     

超宽带实用型介质谐振器天线研究与设计

现代无线通信技术为了减少系统复杂性,对单一天线带宽的性能要求越来越高,故设计一种具有实用性的超宽带介质谐振器天线(DRA)。该天线采用微带线缝隙耦合馈电方式,通过微带线给接地板上的矩形槽和"U"型槽馈电,然后通过槽将电流输入到介质谐振器中。为了防止电磁波的散射,在介质谐振器背面附上寄生贴片,上部加入反射板,可以将天线的性能大幅度提高。该天线分别谐振在5.25 GHz和6.3 GHz,工作在4.6~6.8 GHz,其中5.1~5.9 GHz是WLAN波段,其阻抗带宽达到了39%,因此具有很好的实用价值。该天线的仿真结果由电磁仿真软件得到,通过Agilent Technology PNA N5245A矢量网络分析仪测量天线的回波损耗及增益,得到的测量结果和仿真结果吻合。     

强耦合阵列中匹配网络设计及对天线性能影响

为研究强耦合阵列匹配网络对收发状态下性能影响以及评估该匹配网络在两种状态下的通用性,以网络散射理论为基础,分别在发射和接收耦合天线框架内讨论了该网络参数对阵列性能的影响,并给出了网络不同端接负载条件下的相关函数。理论和计算表明:对于强耦合组成的发射阵列,其匹配网络在收发状态下具有一定通用性;网络负载对天线分集性能具有明显的作用。文章中的理论和方法为研究强耦合阵列特性提供了便利和条件,也为工程实施和应用提供了较强的指导意义。     

Power splitter design for two-element antenna array with high mutual coupling

Design principles for a power splitter driving a strongly coupled two-element handset array antenna have been derived and studied. Splitter circuits using lumped elements and distributed microstrip elements were designed and tested. The results show reasonable agreement between measured and theoretical results.     

The mutual coupling and diffraction effects on the performance of aCMA adaptive array

The performance of the constant modulus algorithm (CMA) with the steepest descent method used in an adaptive array of monopole antennas mounted on a rectangular conducting plate was investigated. The mutual coupling (MC) effect among the array elements and the diffraction effect caused by the conducting plate were taken into account in the calculation by a hybrid method of moment method (MM) and geometrical theory of diffraction (GTD). Simulations showed that the CMA adaptive array performs differently when the MC and the diffraction effects are taken into account. In some cases, the speed of convergence is slower with MC, and in other cases it is faster. Also, in multipath scenarios the array sometimes converges on a weaker delayed ray rather than the direct ray when MC is included. The capture property is explained by the fact that the CMA algorithm is sensitive to initial conditions and the initial array pattern is directional due to MC-not omnidirectional as in the ideal case. The performance of the array on a finite ground plane is different from that on an infinite ground plane due to diffraction effects     

宽频带干涉仪测向圆阵中的互耦效应

运用相关处理方法对互耦情况下的宽频带干扰仪测向圆阵特性进行了分析，研究了互耦存在时的宽频带干扰仪测向圆阵设计原则。     

Mutual coupling effects on a dipole log periodic when used as an array element

A measurement program conducted to observe the effects of mutual coupling on element VSWR in a three element linear log periodic dipole antenna array is described. The data collected are presented as a function of frequency, interelement spacing, and scan angle.     

A novel low mutual coupling microstrip antenna array design using defected ground structure

Defected ground structures (DGS) have been developed to improve characteristics of many microwave devices. In this paper, using FDTD method, effect of DGS to mutual coupling reduction of a two-element microstrip antenna array is investigated. The proposed DGS antenna is compared to other techniques and is shown to have an exceptionally lower mutual coupling between two E-plane coupled elements. Impact of the designed DGS on higher-order modes and radiation pattern of the antenna array is also examined.     

高功率线阵半导体激光器光纤耦合设计

本文通过分析高功率线阵半导体激光器的激光输出特性，设计了一种微台阶反射镜阵列对其进行光束变换，并分别采用几何光线追迹法和高斯光束的ABCD定律，模拟计算了光束变换情况。计算结果表明，本文设计的光束变换系统，可将10mm宽的线阵半导体激光器的输出激光耦合进一根芯径为800μm，数值孔径NA≥0.37的光纤中。     

Mutual coupling on a cylindrical array of waveguide elements

This communication presents a modal approach for investigating mutual coupling on a cylindrical array of waveguide elements. Computed results are given in the form of element patterns and are compared with measured patterns.     

Higher order mode coupling effects in the feeding waveguide of a planar slot array

The effect of internal higher order modes in the feeding waveguide of a planar slot array is investigated. Both the centered-inclined coupling slot and the longitudinal-transverse coupling slot are considered. Method of moments solutions to pertinent coupled integral equations are investigated for arrays of coupling slots of the centered-inclined and longitudinal-transverse types between a main waveguide and crossed branch waveguides. It is demonstrated that, by including the TE/sub 20/ mode coupling in the analysis, most of the higher order mode effects can be accounted for in reduced height waveguides, whereas in waveguides of standard height there may be a small additional effect arising from the TE/sub 01/ mode coupling.<>     

Synthesis of onboard array antennas including interaction with themounting platform and mutual coupling effects

The synthesis of array antennas mounted on ships, or any other vehicular platform, is addressed here. Both the mutual coupling between the array elements, and their interaction with the mounting platform, are considered and introduced into the synthesis procedure. This is done by using a three-dimensional formulation of the method of moments, which models the currents induced on the platform and the antennas, combined with an optimization procedure. Some results are presented, illustrating the capability of the proposed synthesis method     

Conformal array synthesis including mutual coupling

A pattern synthesis technique for a conformal array antenna on a cylinder is presented using the method of alternate projections. Both the sidelobe region and the shape of the main beam are controlled. The method includes the effect of the mutual coupling in the synthesis. It is shown that if mutual coupling is neglected, then poor results are obtained, especially in the shaped beam region     

基于国标音频编码标准DRA/DRA+的同步传输系统

本文对基于DRA/DRA+音频压缩算法建设和应用的音频同步传输系统进行了介绍,详细阐述了基于自主研发的DRA/DRA+音频同步编解码器为核心设备,建设的多个音频同步传输系统应用,并对系统建设后在广播传输、覆盖系统中的实际应用项目进行了阐述和分析。最后对基于DRA/DRA+的音频同步传输技术的推广应用的发展前景做了展望。     

Multifunction wide-band array design

High-performance active arrays operating over C, X, and Ku-band have been demonstrated using newly developed designs of wide-band radiating elements and wide-band monolithic microwave integrated circuits (MMICs). The advanced shared aperture program (ASAP) explored the development of wide-band multifunction arrays capable of simultaneous and time interleaved radar, electronic warfare, and communications functions. Two iterations of radiating element and transmit/receive (T/R) module design were completed during this program. The radiating aperture design approach, overall array concepts, and current design technology and performance are summarized     

Mutual coupling compensation in small array antennas

A technique to compensate for mutual coupling in a small array is developed and experimentally verified. Mathematically, the compensation consists of a matrix multiplication performed on the received-signal vector. This, in effect, restores the signals as received by the isolated elements in the absence of mutual coupling. This technique is most practical for digital beamforming antennas where the matrix operation can be readily implemented     

一种基于亚字并行的可重构阵列设计

设计了一种面向多媒体处理的8×8可重构处理阵列,并在该阵列基础上,对其粒度进行改进,提出了一种基于亚字并行的改进型可重构阵列设计思路.该设计根据图像处理中的算法的位宽特点,实现了一种数据的高位和低位可以同时运算的可重构阵列单元,有效提高数据的并行度,使得阵列的处理速度得到了显著的提高.在典型的图像处理中,这种改进型可重构阵列的处理能力较原来增加了一倍.     

Loop coupling to a periodic dipole array

Conditions are found experimentally for optimising the coupling between a looped feeder (transposed transmission line) and a log-periodic array of radiating dipoles. Under optimum conditions, the coupling is sufficient to be useful in practical antennas.