Mutual Interference of Millimeter-Wave Radar Systems

This paper examines the probability that any millimeter-wave radar systems will interfere mutually by considering spatial, temporal, and operational frequency-related overlaps. It examines the nature and magnitude of the interference under different conditions and for different sensor types before concluding that in an overlapping frequency band, the probability that interference will occur is high. It goes on to demonstrate that, though there are some forms of interference that can be identified and controlled, there are others which are impossible to isolate, resulting in degraded target detection performance and tracking     

On the Generation of Mutual Interference Matrices

This paper is concerned with the presentation of an algorithm for the construction and display of a mutual interference chart of any size from a list of interference lines belonging to any paired transmitter and receiver. Such charts have found use in procedures for assignment of noninterfering frequencies in a communication network. This algorithm is primarily concerned with the interpretation and conversion of lines of interference, having an arbitrary width, from a continuous frequency space to a discrete integer space represented by a mutual interference chart. The widths of the interference lines are related to equipment frequency guardbands. The discrete integer space is related to equipment channel and band numbers. The method of construction is proved to be consistent with respect to element value assignments.     

IR-UWB技术互干扰性及DAA技术的研究现状

超宽带（UWB：Ultra—widthband）是指信号的一10dB相对带宽超过中心频率的20％,或一10dB绝对宽带超过500MHzI“。UWB通信系统作为一种新颖的室内短距离无线电通信系统正在受到广泛的关注。     

编队中雷达互扰模型研究

舰艇组成编队时,雷达间可能有新的干扰产生,需要对编队雷达进行互扰预测分析。给出了雷达间干扰产生的条件,并建立了编队互扰预测模型。该模型考虑到了影响编队中不同舰船平台上雷达互扰的所有因素,能够较精确地对编队中雷达互扰进行预测。     

Coaxial Cables as Sources of Intermodulation Interference at Microwave Frequencies

Intermodulation interference arising from nonlinearities in braided coaxial cables at microwave frequencies is discussed. Detailed investigations have been carried out using a large number of commercially available and specially constructed cables to isolate and assess the relative contributions of different parameters of coaxial cables responsible for the generation of intermodulation products (IP's) at L-, S-, and C-band frequencies centered on 1.5, 3, and 5 GHz. Ambient temperature in the case of polythene dielectric cables and oxides on copper-wire braids affect considerably the IP's generated in a coaxial cable.     

不同频率位置的窄带干扰对DSSS通信性能的影响分析

衡量窄带干扰抑制算法性能高低的一个主要标准是评估干扰处于最恶劣频率位置时的干扰输出平均功率的大小。在扩频序列周期很长且严格平衡的理想条件下,最恶劣干扰的频率位置为DSSS信号载波频率。基于典型的m序列DSSS系统,分析了处在不同频率位置的窄带干扰对DSSS系统的影响,所得结果与理想条件有所不同,这对于扩频系统的设计与应用具有指导意义。     

Suppression of Time-varying Multi-tone Interference Based on Frequency Domain Interference Detection

Existing active multi-tone interference (MTI) suppression methods used in direct sequence spread spectrum (DSSS) consider the interference to be time-invariant. However, in most practical scenarios, the interference is time-varying. These conventional analytic models cannot be directly applied to current realistic systems with time-varying interference. Hence, in this paper, we propose a novel approach based on frequency domain interference detection to suppress MTI experiencing a time-varying fading channel. Our approach operates in two steps. Firstly, we calculate the interference decision threshold by the probability of false alarm based on the Neyman-Pearson (NP) criterion. Secondly, we consider that the frequency bin is corrupted by interference, and the corresponding point is set to zero if the magnitude of the received signal exceeds the threshold. The simulation results demonstrate that our proposed method can mitigate time-varying MTI effectively, and can approach the interference-free performance limit over practical ranges of interference power levels and mobility levels.     

Frequency Control of a Resonant Radio Absorber with a Free Space

Journal of Communications Technology and Electronics - Abstract—Numerical calculations of the matching of a resonant radio absorber (RA) have confirmed that the ideal matching of such an RA...     

Mutual Coupling Between Box-Horn Elements of a Phased Array Terminated in Three-layered Bio-Media

The ldquoplane wave spectral techniquerdquo is used to investigate theoretically the extent of mutual coupling between two box-horn elements of a phased array terminated in three-layered bio-media (skin, fat, and muscle layers). The results obtained have been validated against published results in the literature. Each box-horn of the array is assumed to be filled with water to provide good impedance match to the bio-media. Also, it reduces the dimensions of each box-horn which makes it suitable for array configuration. The effects of relative position of elements, spacing between elements, frequency, aperture size of each element, relative phase and amplitude of excitation of the elements on mutual coupling coefficients are numerically investigated and presented for an array of two box-horns terminated in bio-media. The specific absorption rate (SAR) distributions along the direction of the array axis in muscle layer of the bio-media in direct contact with a collinear array of two box-horns both with and without mutual coupling considerations are also computed and presented. The results of the present research work can provide useful design guidelines for the development of prototypes of box-horn array for hyperthermia treatment of tumors. Bio-media, box-horn, hyperthermia, mutual coupling, phased array, plane wave spectra.     

电磁干扰中元件的高频特性研究

电力电子设备产生的电磁干扰都会超过可接受的水平,所以要利用滤波电路降低他们产生的EMI,这些滤波电路由串联扼流圈和并联电容器构成低通滤波器,文章对EMI滤波元件的高频特性进行分析,给出了电容、电感、电阻等的高频特性、等效电路以及仿真曲线。得出的结论体现出与工频下不同的特性,对滤波设计有重要指导意义。     

Interference and Sharing at Medium Frequency: Skywave Propagation Considerations

A considerable amount of work dealing with nighttime skywave propagation has been done; however, some areas remain to be explored. For example, short-term variation of field strengths has been overlooked. Daytime propagation is far from being quantitatively understood. Also, it is not quite possible to determine interfering signal levels which may be present for a small percentage of time with high accuracy. During sunspot cycles 18 and 19, the Federal Communications Commission conducted an extensive field-strength measurement program in the midlatitude areas of North America. These and other data are revisited with a new emphasis, namely interference and sharing. This paper discusses, among other things, determination of field strengths exceeded for different percentages of time (1 to 99%), diurnal variation of field strengths, favorable conditions for daytime skywave propagation, effect of magnetic storms, frequency dependence as observed at daytime and nighttime. *Views and opinions expressed in this paper are those of the author and should not be interpreted as official FCC policy.     

Frequency assignment: Theory and applications

In this paper we introduce the minimum-order approach to frequency assignment and present a theory which relates this approach to the traditional one. This new approach is potentially more desirable than the traditional one. We model assignment problems as both frequency-distance constrained and frequency constrained optimization problems. The frequency constrained approach should be avoided if distance separation is employed to mitigate interference. A restricted class of graphs, called disk graphs, plays a central role in frequency-distance constrained problems. We introduce two generalizations of chromatic number and show that many frequency assignment problems are equivalent to generalized graph coloring problems. Using these equivalences and recent results concerning the complexity of graph coloring, we classify many frequency assignment problems according to the "execution time efficiency" of algorithms that may be devised for their solution. We discuss applications to important real world problems and identify areas for further work.     

自由空间微光学元件的研制

介绍了一种新近产生的被称为自由空间微光学平台（ Ｆ Ｓ Ｍ Ｏ Ｂ）的三维空间集成光学系统。并提出了一种用二氧化硅（ Ｓｉ Ｏ２）作光学材料、光刻胶和溅射铜（ Ｃｕ）薄膜作牺牲层、电镀铁镍（ Ｆｅ Ｎｉ）作支撑结构的制作自由空间微光学元件的新工艺。研制成功了多种与基底相垂直的三维位相型微光学元件。     

利用时频分析抑制射频干扰

提出了一种适合于线性调频体制射频干扰滤除的方法,该方法基于短时傅立叶变换(STFT)的基本原理。针对单一频率的射频干扰在线性调频体制中非平稳性和瞬时性的特点,利用STFT 对含干扰的信号进行分析,并且在时频分布上利用特征值分解的方法得到信号子空间和噪声子空间,利用信号子空间构造投影矩阵滤除射频干扰的影响。经过实测数据的检验,信噪比提高了近10 dB,表明该方法能有效地解决射频干扰的抑制问题。     

同频异极化干扰与极化的调整

随着通信事业的飞速发展,卫星轨道和转发器频率资源越来越紧张。同一卫星上,不同极化方式同频转发已广泛采用,利用不同极化方式间的极化隔离度区分不同的信号。由于极化调整常常不被重视,极化隔离度下降,造成非外界因素的干扰。我们曾几次遇到过模拟信号网纹、数字信号马赛克甚至中断的现象,经与当地无线电管理委员会协调,不存在同频干扰。反复调整方位角、仰角甚至加装线路放大器,均无效果。这说明异极化干扰问题已非常突出。因此极化调整的问题必须引起进一步的重视。     

TD—SCDMA系统频率干扰分析

针对目前中国三大移动运营商3G频谱的分配情况,对时分同步码分多址（TD-SCDMA）与个人手持机系统（PHS）间的干扰作了理论分析和估算,指出完全通过空间隔离方式难以在城市中规避干扰,通过比较天线垂直隔离和加装滤波器两种主要干扰规避方法,得出加装滤波器条件过于苛刻,而天线垂直隔离更易于操作,为目前两个系统的现网共存和发展提供了理论和实践指导。     

用MOM-UTD混合方法计算共形天线阵单元间的互耦

采用矩量法(MOM)结合一致性绕射理论(UTD)来计算共形天线阵单元间的互耦。这种混合方法通过UTD来修正MOM中的广义阻抗矩阵将理想导体曲面对天线的影响考虑在内。克服了单独采用这两种方法的缺点。既减少了计算量又达到了一定的精度。计算结果与文献中已有的结果吻合得相当好。     

采用电视行频辅助鉴相克服鉴频干扰

在采用频率合成器技术的电视发射机中,鉴相频率与电视行频不同步常常造成鉴频干扰画面的现象,讨论采用视频行同步脉冲作辅助鉴相的技术原理克服鉴频干扰的方法,简述异或门鉴相器的工作原理。     

Main Effect of Mutual Interference in Radio Communication Systems Using Broad-Band Transmitters

Present-day radio communication systems employing antijam techniques, such as frequency hopping or spread spectrum, require that the transmitter final stage be a broad-band solid-state device. An analysis of such radio communication systems has shown that these systems suffer from the effects of intermodulation (IM) products generated within the transmitters, especially under collocation situations. A qualitative analysis of the transmitter IM-product interference sources is followed by the development of a computational method for obtaining their disturbing effects on a VHF/FM radio system operating under severe tactical collocation scenarios. The computed results for other mutual interference sources upon the system are also presented. The numerical results of the developed computer printout are discussed and conclusions presented, which contribute to obtaining a clearer insight into the mutual-interference sources within the system, especially from the transmitter IM disturbances.     

秩损法互耦校正在GPS抗干扰中的应用

GPS空时联合(STAP)抗干扰技术是基于自适应波束形成的信号处理方法,通过干扰置零,能够对抗高功率的宽带和窄带干扰。理想的算法认为各个阵列天线之间互不影响,然而实际应用时,各个天线之间会产生互耦,严重影响系统性能。针对此,对自适应天线阵列及其互耦进行了建模,并采用秩损法进行互耦校正,最后将校正结果与分离迭代互耦校正算法作了对比。仿真结果表明,秩损法互耦校正不仅能够有效补偿系统因天线互耦损失的性能,而且在较高输入干噪比下其性能优于分离迭代算法。