共查询到20条相似文献,搜索用时 890 毫秒
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为实现低副瓣数字阵列天线性能,需要对阵面通道幅相误差进行校准。针对此问题,定性分析了通道幅相误差、阵面通道数与数字阵列天线主要性能(副瓣电平、波束指向、增益)的相对关系,分析结果表明:通道间幅相误差越大,副瓣电平、波束指向、增益越差;通道数越多,副瓣电平、波束指向受通道误差影响越小,而增益受通道幅相误差的影响与阵面通道数无关。结合数字阵雷达实际使用中阵面通道幅相误差修调问题,重点研究了通道误差测量方法。给出了利用内监测法和中场测量法进行通道误差测量的原理、实现方法及适用条件,该2种通道误差测量方法可以作为互补手段使用。最后,给出了一种基于多次测量取平均值的数字阵列幅相误差校准方法,仿真结果表明:校准前后,通道幅相误差分别由2 d B和20°变为0.4 d B和2°,满足指标要求。 相似文献
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星载DBF Tx射频通道幅相误差校正 总被引:1,自引:0,他引:1
为了实现精确的多波束形成,该文提出了一种补偿卫星通信多波束系统发射通道幅相误差的校正方法,该方法在发射通道中同时注入多路正交码变换的校正测试信号,通过接收多路发射机的输出信号和,在基带校正算法单元利用正交码的时间相关性和IDFT并行处理的方法,同时得到多路射频通道的校正因子,并对得到的校正因子进行了归一化处理,消除了对通道中非线性器件的影响.仿真结果表明,该方法可以有效地补偿射频通道间的幅相不一致性,校正后的波束方向图接近理想的波束方向图. 相似文献
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讨论形成左、右交叉波束宽天线阵的设计,运用泰勒级数展开对微波网络幅相不平衡引入的天线交叉波束指向误差进行分析计算,并用一组试验数据验证了分析计算的正确性。 相似文献
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Tapering the resistivity on the surface of an object modifies the scattering patterns of that object. For instance, gradually tapering the resistivity on a strip, half-plane, or an antenna ground plane reduces the edge effects of that surface. Greater control over the sidelobe response of the scattering pattern of a strip is possible by relating the resistive taper to a low sidelobe taper via physical optics. The idea of relating antenna aperture tapers to scattering patterns is extended to placing nulls in the sidelobes of scattering patterns of strips. A resistive taper for placing nulls is found by solving the scattering integral equations of a resistive strip for the resistivity, then substituting the desired nulling current density taper into the appropriate equation and solving for the resistive taper. This method is capable of placing multiple nulls in the bistatic scattering pattern or a single null in the backscattering pattern 相似文献
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Reducing the mutual coupling effect in adaptive nulling using are-defined mutual impedance 总被引:1,自引:0,他引:1
Hon Tat Hui 《Microwave and Wireless Components Letters, IEEE》2002,12(5):178-180
The effect of mutual coupling in an adaptive antenna array for the nulling of interferences is investigated. The concept of mutual impedance is re-defined to take into account of the scattering effect due to the other antenna elements in the array. The re-defined mutual impedances are used to reduce the mutual coupling effect by calculating the open-circuit voltages from the measured voltages on the antenna terminals. Results show that by using the re-defined mutual impedances, substantial improvements in term of the depths and the accuracy of the nulls can be obtained over a previous method 相似文献
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The generation of nulls in an antenna pattern by controlling the phase and amplitude of the subarray output signals is investigated. Although the nulls may be formed with any number of subarrays, the subarray configuration and desired null location have a major impact on the distortion in the far-field pattern that results. The distortion problem resulting from subarray nulling is well-known, but little theoretical analysis has been done to explain the cause of the distortion. A theoretical and graphical explanation of why the distortion occurs is offered. 相似文献
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A partial phase-only nulling (PPON) algorithm has been developed and evaluated on a 496-element monopulse phased array antenna system which employs five-bit phase shifters. Using this PPON algorithm allows nulls in the far-field pattern to be steered to the desired directions for a phased array equipped with low-resolution phase shifters to perform simultaneous nulling in the sum and two difference patterns in the environment of multiple jammers. Simulated and experimental patterns are illustrated 相似文献
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基于数字波束形成体制的相控阵雷达系统,如果杂波和干扰的角度先验信息可以获知,则可采用方向图预置零技术进行相关的抑制处理。文中提出一种能够实现可控制方向图零陷宽度和零陷数量的处理方法。该方法采用对阵列方向图响应矩阵的奇异值分解和重构,进行扩展的零空间基向量的求解。同时,针对提出的新方法的实际应用,论文给出了一种可实用的求解算法 相似文献
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A method is discussed of suppressing jammers simultaneously in the sum and the difference patterns of a linear antenna array by either using complex weights or controlling the current amplitudes only, with special emphasis on the latter method. For a given array size, the total number of jammers that can be nulled is doubled if complex weights are used instead of real weights. However, the amplitude-only technique has many attractions. It is shown that because the resulting current amplitude distribution has a double symmetry, the number of attenuators required for simultaneous nulling can be as low as a quarter of the total number of elements in the array. This means a much faster computing speed as well as a considerable saving in hardware. The method also allows the main beam of the antenna to be scanned by using phase-shifters while nulls are placed in directions of known jammers in both the sum and difference patterns by using attenuators. As a result, the maximization of the signal-to-jammer ratio can be achieved with relative ease, because the stronger a jammer is, the easier it is to locate it and hence to suppress it. 相似文献
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Heng-Cheng Lin 《Antennas and Propagation, IEEE Transactions on》1982,30(2):212-223
A receiving array antenna can steer its main beam toward any direction by adjusting the complex weight in each element. However it cannot always steer one beam and one null toward two prespecified directions simultaneously with a single set of weights. The ability for an array to steer one beam and one or more nulls simultaneously is determined by five factors: 1) element positions, 2) orientations of elements, 3) antenna patterns of elements, 4) polarizations of signals, and 5) directions of the beams and/or nulls. A coefficient is defined, called spatial correlation, which includes these factors and completely characterizes array beam pointing and nulling. Its application to adaptive arrays is demonstrated. The adaptive array performance is dominated by this coefficient and can be improved by properly choosing the first three factors. Several examples on the selection of element placement in adaptive arrays are presented. 相似文献
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针对GPS抗干扰问题,常用手段是在信号处理系统中采用自适应调零算法来实现抗干扰。结合该算法文中给出了一种信号处理系统的硬件实现方案。首先概述GPS自适应调零天线的系统结构,然后给出信号处理系统的硬件设计思路及其功能模块的实现,最后通过实测数据验证硬件模块可以满足自适应调零算法的要求。 相似文献
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A medium access control (MAC) protocol (NULLHOC) for ad hoc networks of nodes with antenna arrays is presented. The antenna
array is used for transmit and receive beamforming with the purpose of increasing spatial reuse by directing nulls at active
transmitters and receivers in the neighborhood. In contrast to previous work with directional antennas, our approach is applicable
to multipath channels, such as occur indoors or in other rich scattering environments. The MAC protocol is designed to support
the control information exchange needed to direct nulls toward other users involved in existing communication sessions. Knowledge
of the channel coefficients between a transmitter or receiver and its neighbors is used to design transmit or receive beamformer
weights that implement the requisite nulling. Simulations are used to demonstrate the improvements in throughput and transmit
powers that are obtained in this approach relative to the IEEE 802.11 MAC protocol. We also analyze the effects of channel
estimation errors on our protocol and propose a simple modification of the basic (NULLHOC) protocol to minimize their impact.
This work was supported in part by National Science Foundation grants ECS-9979408 and ANI-9980526. Any opinions, findings
and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect
the views of the funding agencies. 相似文献