EMC测试中天线系数的误差分析

指出了目前正在使用的两种天线系数校准方法的不足；引入了配置天线系数及其配置不确定度的概念；提出了减小天线配置不确定度的途径。     

机载天线间耦合度分析计算

在电磁兼容领域的研究中,时于两副天线所组成的系统的电磁兼容性,用耦合度来描述它们之间的相互作用是非常准确有效的方法.该耦合度由系统中发射天线增益、接收天线增益、天线极化匹配系数、屏蔽系数、发射与接收天线间最短距离等因素决定.仿真计算给出了飞机上不同部位两天线间的耦合系数.     

利用射电星校准13m测控天线指向误差及测试结果

分析了利用射电星校准13m测控天线指向精度的方法,综合利用射电星和光标测试数据,采用简化的天线误差模型,计算出天线误差系数,经过误差修正后天线的指向精度达到设计要求。     

天线测量理论中的基本方程组

提出了天线远场测量理论中的基本方程组,并由此导出目标的雷达散射截面、天线增益以及天线系数等参数的重要计算公式。     

高教机天线布局影响通讯距离研究与改进

某型高级教练机在试飞中,出现空地通讯距离不满足战技指标要求的问题。经过分析发现,由于超短波电台天线作为单极天线,其安装布局未满足天线本身要求,即接地面尺寸过小、近场区环境复杂等,导致天线辐射性能受到影响。本文对天线阻抗和方向性系数进行了研究分析,并根据飞机情况制定相应的改进方案。     

机载拖曳天线动力学建模与仿真

拖曳天线在空中的构型及垂直度是检验天线能否正常发射甚低频信号的主要依据,是设计人员必须着重考虑的因素.通过对其运动状态及其受力进行分析,建立机载甚低频拖曳天线动力学模型.针对其稳态动力学模型,运用Newton-Raphson迭代进行求解,计算出了天线垂直构型和天线的张力分布情况.通过与AD报告计算结果进行比较,证明所建立的动力学模型是可信的.最后分析了空气系数和天线末端质量对天线垂直构型和天线张力分布的影响.     

副反射面调整模型及工程实现方法

针对大型反射面天线重力变形导致天线性能恶化的问题,提出了用副反射面实时调整减小重力变形影响的方法,分析了副反射面位置平移和旋转对天线增益和指向的影响,并建立了副反射面姿态随天线仰角角度变化的数学模型。用数字摄影测量得到了一组35m天线在不同仰角时的主反射面变形数据,并进行最佳吻合,从而得到一组副反射面最佳位置坐标,再与测量的对应仰角的副反射面在重力作用下的自身位移数据叠加,可以得到一组最终副反射面调整数据。将其代入数学模型,用最小二乘法进行最佳拟合,求出数学模型系数,再将该模型用于副反射面实时调整系统,则可减小重力变形对天线性能的影响。仿真结果表明,采用该模型对副反射面位置实时调整后,35m天线在X和Ka频段的天线增益分别提高了约0.52dB和1.95dB。     

30—1000MHz干扰场强仪场强和脉冲响应的校准

扼要地阐述了采用标准偶极子天线作为工作标准，核准30～1000MHz干扰场强测量仪的天线系数的原理、场地确定和方法，还阐述了此频段脉冲响应测试校准的要求和方法。     

电场辐射干扰测试中天线系数的校准

论述了屏蔽暗室电场辐射干扰测试中天线系数几个基本校准方法的原理；指出了现有某些规范中校准方法的不足，提出了一种新的供屏蔽暗室使用的校准方法——接收天线多维校准法．     

基于HFSS的机载天线方向图研究

简要分析了机体结构对机载天线方向图的影响,并采用HFSS软件的高频积分方程(HFSS-IE)求解器对甚高频(VHF)频段的天线进行仿真,对比不同位置处天线方向图变化,分析了方向图变化的产生原因,可在早期飞机研发设计中为天线布置提供参考。     

Frequency reconfigurable antenna actuated by inflated triangular structure: Design and analysis

This paper proposes a frequency reconfigurable triangular antenna actuated by an inflated triangular structure. The open path antenna is transformed from an open type to a closed structure by inflating. Inflatable structures are easy to manufacture by fusing 2 inextensible membranes together along a defined pattern of lines. However, the prediction of their deployed shape remains a challenge. To solve the pattern changed problem, guided by geometric analyses and local buckle characteristics, the inflated triangular structure has been designed and verified by experiment and simulation. In the process of transformation of the antenna, the resonant frequency of the antenna is changed because this frequency is determined by the conformational change. The resonant frequency changes from GHz to kHz when the design of initial structure sizes is from millimeter to meter. The measured peak gains, the frequency, and the radiation direction are also reconfigurable by the initial size. Finally, the reconfigurable resonator array is presented, which is coupled to electric fields to absorb all incident radiation. In this work, the changed pattern design by inflating is applied to the antenna design, and its frequency reconfigurability is achieved. Through the electricity performance analysis of the reconfigurable antenna, precise manufacturing will be possible and provide guidance for manufacturing frequency reconfigurable antennas.     

浅析水平扭转M型下滑天线对入口高度及下滑角的影响

对于M型下滑天线,对天线作微调能改变近场DDM分布,从而对入口高度产生影响。本文阐述了扭动天线及调整辐射场形的原理。通过扭动上、下天线,定量分析入口高度和下滑角的改变量与扭动距离的依赖关系,并对飞行校验中的实例进行比较。对比扭动对近场(入口高度)和远场(下滑角)的影响。理论计算得出:上天线向跑道方向扭动一定角度,可以明显提高入口高度,向跑道外侧扭动后,入口高度减小;扭动下天线情况则相反,且两者基本都不影响下滑角。因此表明,扭动天线是一种有效改变近场的方法。     

深空探测多天线组阵的增益损失研究

为定量分析上行天线组阵增益损失的影响因素,提出一种通过建立数学模型分析合成损耗的估计方法.首先基于天线原理和电磁波传输理论建立了天线组阵上行链路信号的数学模型,以统计学理论对数学模型进行分析,得到了影响上行链路信号的若干因素.通过分析得出,深空探测信号在远距离传输中因大气相位扰动引起的误差是造成天线组阵增益损失的最主要因素.再通过对大气相位扰动误差的进一步分析,构建S频段和X频段下大气相位扰动的空间自相关模型和时间自相关模型,得到组阵基线长度和工作仰角同合成损耗的关系.经过对各误差源的分析可知,在目前的技术水平下,能够满足上行天线组阵工程应用的精度要求.     

The Effect of Satellite Spin on Two-Way Doppler Rangerate Measurements

The rotation of a spin-stabilized satellite employing a turnstile antenna for reception and retransmission affects two-way Doppler range-rate measurements. Two different types of tracking systems are considered and, in both systems, the range-rate measurement is changed by the amount begin{equation*} |Delta dot{r}| = frac{|1 pm 1/k|}{2} lambda_{t}f_{s} end{equation*} where k is the turn-around ratio of the satellite transponder, Xt is the wavelength of the ground-based transmitter, and fs is the spin rate of the satellite. The positive sign is used if the turnstile antenna elements are connected to give the same polarization for both reception and transmission. If the antenna connections result in different polarizations, the minus sign is used and the magnitude of the effect is reduced.     

Noise factor of receiving system with arbitrary antenna impedancemismatch

The system operating noise factor of a receiving system is modeled for arbitrary impedance mismatch of the antenna to the transmission line feeding the receiver. The effect of this mismatch on the noise factors of the transmission line and the receiver is considered. The stochastic nature of the external noise factor is considered. The amount of mismatch that can be tolerated before the internal system noise factor exceeds the external noise factor is determined. Numerical results are presented for a VHF-FM radio receiving system with an electrically short monopole antenna. It is noted that a large impedance mismatch at the antenna-transmission-line interface of a radio receiving system can cause a significant increase in the system internal noise factor (more than a 50-dB increase for a voltage reflection coefficient of 0.999)     

相控阵雷达天线模型及仿真

阐述了相控阵天线仿真的重要性,指出了相控阵天线仿真的主要困难。提出了一种利用阵因子、方向性因子和旁瓣抑制因子分别解决仿真波束形状、天线增益、方向图旁瓣及其变化等3大问题,并进行综合建模和仿真,给出了综合后的仿真模型。该仿真模型保证了理论方面的精度,优化和减少了仿真计算步骤和计算量。利用该仿真模型,给出了宙斯盾系统的AN／SPY-1D雷达天线的仿真计算实例。     

The Segmented Aperture Synthetic Aperture Radar (SASAR)

A new concept in synthetic aperture radar, called SASAR, which uses a segmented aperture, is described. Use of the segmented aperture allows appreciable extra receiving antenna gain to be realized. Each subarray of the receive antenna is equal in length to the transmit antenna; the system performance is increased approximately by a factor equal to the number of subarrays. To allow array combination of the subarray signal outputs requires a phase-shift factor (varying with azimuth) to be applied to each subarray signal. A digital implementation of this preprocessor is sketched out; it uses a push-down storage stack to store the range histories for a synthetic aperture from each subarray. Appropriate phase shifts are added to the stacks and a sum of stack values then provides the combined output range history sequence. Possibilities of using analog delay lines for preprocessing are also discussed. Pattern errors due to subarray size and receive array near field are examined and constraints are given.     

Noise factor and antenna gains in the signal/noise equation for over-the-horizon radar

A recommended form of the signal-to-noise equation that includes both internal and external system noise and signal/noise processing losses is discussed. The recommended form conforms to the internationally accepted definition of system operating noise factor but is extended to include signal/noise processing. The predetection signal-to-noise ratio (SNR) of a radar or communication system is proportional to the power gain of the transmit antenna and the directive gain of the receive antenna, and is inversely proportional to the operating noise factor of the receiving system. The operating noise factor is approximately equal to the product of the external noise factor and the signal/noise processing factor when the system is external noise limited, as is usually the case for over-the-horizon (OTH) radar.<>