一种应用遗传算法的阵列天线共址干扰抑制技术

针对有限大平台部署多种传感器导致的严重的自干扰问题,提出了一种应用遗传算法实现的阵列天线共址干扰抑制技术。首先针对同平台上的阵列天线和其他天线建立了辐射和接收模型,然后将辐射特性和接收机抗干扰特性分别抽象为最优化问题的目标函数和约束条件,最后通过遗传算法进行最优化求解。该技术在不同辐射角度时能抑制共址干扰,具有一定的工程实用价值。     

Slot stripline circular-polarization antennas for a few-element antenna array for a high-accuracy receiver of signals from global navigation satellite systems

New radiators for slot stripline leaky-wave circular-polarization antennas for high-accuracy GLONASS/GPS receivers have been developed. The main technical characteristics of antennas with new radiators have been theoretically and experimentally studied. It is shown that application of the new radiators improves the axial ratio, increases suppression of the cross polarization, increases the stability of the antenna phase center, and thus can increase the GLONASS/GPS positioning accuracy. The results of the analysis of the GLONASS/GPS positioning accuracy with the use of these antennas in an angle-measuring receiver and as elements of a few-element antenna array are presented.     

宽带干扰背景下的多阵元卫星导航信号模拟

近年来全球导航卫星系统(GNSS)抗干扰技术逐渐成为研究热点,在抗干扰研究中,宽带干扰背景下的多阵元卫星导航信号模拟发挥着至关重要的作用。为了提高抗干扰研究效率,通过Matlab模拟的方法研究了卫星导航软件接收机入口数字中频信号的模拟问题。根据信干噪比进行功率控制,分别对卫星导航信号、干扰信号和噪声信号进行建模,计算阵列天线带来的延时,最后模拟了宽带干扰背景下阵列天线的卫星信号并设计了图形用户(GUI)界面。在模拟完成后,将信号输入到抗干扰算法的研究系统进行测试,解决了抗干扰研究中复杂的干扰信号源模拟问题,提高了抗干扰研究的工作效率,同时验证了本研究的实用性和正确性。     

一种新型和差旁瓣抑制阵列天线

针对传统和差阵列天线旁瓣抑制能力的不足,设计了一种应用于二次雷达的新型和差旁瓣抑制阵列天线.该天线主要由前向阵列、后向单元、波束形成网络和互连的射频电缆构成,其中前向阵列和后向单元共同形成差波束.采用遗传算法对各个天线单元的幅度和相位进行优化,使差波束在工作频带内能够覆盖和波束的旁瓣.仿真和测试结果表明:在13.2％相...     

Adaptive multiuser interference suppression for CDM satellite systems

This paper deals with the application of linear multiuser detectors in mobile terminals of code division multiplex (CDM) satellite systems. Generally, the interference caused by other users can dramatically reduce the performance of a CDM‐based satellite communication system. Since no spreading information of other users is given and since there are no trainings sequences, a blind adaptive interference detector with low complexity is needed. In order to implement a detector for suppressing the interference from other users, different adaptation algorithms can be applied. Comparing them in terms of complexity, adaptation speed and bit error rate, the LMS (least means squares) algorithm with adaptive step size shows the best performance. However, the implementation of this algorithm in a satellite system still leads to high processing times. For this reason, two new schemes with reduced complexity are presented. A very important point is, that the adaptive algorithms are basically restricted to short spreading codes (code period equals symbol period) whereas CDM‐based satellite systems use long codes (one‐code period spans over multiple symbols). In this paper, a new scheme is presented which can be applied to long codes. By cascading multiple separated interference detectors the adaptation is done every time when the same part of the spreading sequence appears. Copyright © 2005 John Wiley & Sons, Ltd.     

Coherent interference suppression by an antenna array of arbitrarygeometry

An approach is investigated that can be applied to an array of arbitrary geometry for coherent and incoherent interference suppression. This approach consists of constructing a weight vector which minimizes the array output power subject to null constraint in the directions of the coherent interferers. In this way, the coherent interference is suppressed by the null constraint and the incoherent interference is suppressed by minimizing the array output. The approach requires the estimation of the angles of arrival of the coherent interferers. A simple bearing estimation method is described which can be applied to the scenario of one coherent interferer. The effect of error in bearing estimation on the array performance is discussed. The use of a high-order null constraint to counteract that error is discussed     

耐高温卫星导航天线

设计了一种陶瓷基底的右旋圆极化微带天线,能够满足高温环境下卫星导航系统的应用.天线设计特点有以下四点:天线外形具有低轮廓特性, 适合高速运动飞行器表面的贴装; 采用钛合金材料和高温陶瓷材料, 能够在400 ℃高温环境下正常工作, 具有优异的耐热性能; 加工装配流程均无焊接工艺, 确保天线组件的电连接在高温冲击下的可靠性; 采用中心短路销钉设计, 减少同轴馈针的感抗, 获得优异的阻抗匹配特性.通过仿真优化和实际测试, 验证了该天线性能优异, 满足高温环境下的卫星导航系统的使用要求.     

A self-steering planar array antenna for satellite broadcastreception

The active planar array antenna offers a number of advantages, including use as a portable antenna for easy reception of direct Ku-band satellite television broadcasts. This paper presents a newly developed active planar array antenna which provides electronic beam-tracking without mechanical tracking equipment. The features of the antenna are: (1) use of a series-parallel fed microstrip array, (2) electromagnetically excited array by a coplanar patch connected to the coplanar waveguide, and (3) low noise down-converters and self-phasing units incorporated into the feed circuits for electronic beam-tracking. The paper discusses the design of the coplanar waveguide fed coplanar patch and the configuration of a self-phasing active planar array antenna. The measured gain of the experimental 9-element unit array antenna without active devices is 13.4 dBi at 11.85 GHz. Experimental results for a 216-element self-steering planar array of size 147×220.5 mm are also presented     

A novel scheme for reception using an active microstrip antenna

An unique aspect of the injection-locked active microstrip antenna incorporating a Gunn diode, i.e., the variation of the device current within the lock band, is exploited for the demodulation of an FM microwave signal. A simple experimental arrangement has been presented to demonstrate the demodulation performance of the receiver even in a multichannel environment. Using two such separate antennas as transmitter and receiver, a two-way short-range communication system has been demonstrated that may be suited for certain commercial and military applications     

Co-channel interference canceller using CMA adaptive array antenna

A co-channel interference canceller that uses a constant modulus algorithm (CMA) adaptive array antenna is presented. In this canceller, when a CMA adaptive array antenna captures a co-channel interference signal, a replica of this signal is generated and then eliminated from a received signal, thus a desired signal can be obtained. Computer simulation results show that the proposed canceller can effectively reduce co-channel interference     

Navstar GPS and GLONASS: global satellite navigation systems

Both the Navstar GPS and GLONASS satellite navigation systems, developed respectively by the United States and the Soviet Union (now the Commonwealth of Independent States), are now planned to become operational by the year 1994/95. Both systems are capable of providing the civil community with high-precision position-fixes and/or timing references on a continuous, world-wide basis. For many years both systems have had satellites in orbit in order for pre-operational testing to be conducted. The paper discusses (a) the widely-differing launch histories of both systems, (b) developments in the planned use of orbits, (c) the deliberate degradation of accuracy by the use of selective availability and (d) progress in plans to provide a joint Navstar GPS/GLONASS civil satellite navigation system, possibly integrated with other satellite ranging systems     

A novel array antenna for MSAT applications

The issue of reducing the cost of phased array vehicle antennas through the use of a lens feeding arrangement instead of phase shifters at each element is addressed. In particular, the economic viability of a mobile satellite system (MSAT) is largely dependent on the efficient use of the allocated scarce spectrum and orbit as well as the satellite power. The type of vehicle antenna used will play a critical role in achieving this efficiency. A standard design approach for an electronically steered array uses phase shifters at each element to provide beam steering. A method for reducing the required number of phase shifters by using an R-KR lens feed network is outlined. The authors briefly discuss the phase shifter approach to beam steering, examine various lens feed techniques, and describe the R-KR lens approach. The lens feed network architecture is examined, a computer model for simulation of the array is presented, and the results of analysis of a suggested design for the MSAT application are given. In addition, satellite acquisition and tracking considerations are investigated     

一种新的基于3D有源天线组网的干扰协调方案

传统2D有源天线仅能进行水平维的波束调整,而3D有源天线能够结合垂直维的波束调整,提升系统的吞吐量.由于3D有源天线组网的干扰情况与2D完全不同,需要研究新的干扰协调方案,本文提出一种基于3D有源天线组网的干扰协调方案,通过相邻基站间交互各自对系统资源的使用信息,使得基站间可协调分配系统资源,降低了系统整体干扰水平.仿真结果表明,提出的方案可有效地抑制小区间干扰,提升边缘用户的性能乃至整个小区的平均吞吐量.     

一种考虑反向缝的全球低轨卫星通信系统的波束排布方法

针对全球低轨卫星通信系统的动态性引起的反向缝区域覆盖问题,采用辐射场到地球覆盖区的转换方法,仿真分析了单个卫星服务区为圆形、椭圆和矩形时的全球覆盖情况,并采用椭圆子波束排布对椭圆和矩形的卫星覆盖进行了分析。结果表明,在不增加波束个数的前提下,采用波导缝隙阵的长椭圆子波束,单个卫星矩形覆盖可以有效解决卫星反向缝区域无法完全覆盖的问题。通过对多星影响下的载干比统计方法进行分析,得出这种卫星波束排布方法满足卫星通信的要求,为低轨卫星的天线波束设计提供了理论参考。     

Precoding with interference suppression sequence scheme for OFDM-based cognitive radio systems

Orthogonal frequency division multiplexing(OFDM)is considered to be one of the promising schemes for cognitive radios(CR)systems,due to its flexibility in spectrum shaping.However,the traditional way of spectrum-notching failed to suppress out-of-band leakage enough,resulting in interference with licensed users(LUs).A novel spectrum shaping scheme is proposed in this article,where a precoder with interference suppression sequence(ISS)is for the first time introduced for shaping the spectrum of OFDM signals in OFDM-based CR systems.The precoder matrix together with ISS matrix is obtained by minimizing the power of out-of-band interference,which results in the sufficient interference suppression of OFDM signal to LUs.Analysis and simulation results show that the proposed scheme can significantly suppress the interference power to LUs at a little cost of precoding efficiency.Meanwhile,the peak-to-average-power-ratio(PAPR)is invariable and the bit-error-rate(BER)performance over Rayleigh fading channel is improved.     

A novel turbo coding scheme for satellite ATM using Reed-Muller codes

Block turbo codes with trellis-based decoding are proposed for use in cell-based satellite communication. Shortened Reed-Muller (RM) codes are used as the component codes because their minimal trellis is known. Simulation results for RM turbo codes and shortened RM turbo codes are presented over additive white Gaussian noise and Rayleigh fading channels. The performance of the shortened codes with different shortening patterns are shown. In some cases, the codes have the unequal error protection property, useful in asynchronous transfer mode cell formatting. In order to test the suitability of the proposed coding scheme from a practical point of view, the effect of channel impairments, including channel signal-to-noise ratio mismatch and carrier phase offset, are investigated.     

A novel adaptive beamforming algorithm for antenna array CDMA systems with strong interferers

Blind beamforming based on the maximum signal-to-noise ratio (MSNR) can improve the performance of an array system only when the processing gain of the given code-division multiple-access (CDMA) system is high enough such that the desired signal can become dominant after despreading (see Choi, S. and Shim, D., IEEE Trans. Veh. Technol., vol.49, p.1793-1806, 2000; Choi, S. and Yun, D., IEEE Trans. Antennas Propagat., vol.45, p.1393-1404, 1997). We consider a maximum signal-to-interference-plus-noise ratio (MSINR) beamforming. The MSINR performance criterion is chosen to deal with strong interferers effectively. It is shown that blind MSINR beamforming is possible by directly utilizing the input and output signals of correlators of the CDMA systems. In addition, we propose an adaptive beamforming algorithm at a lower computational complexity - about O(7.5N) - where N is the number of antenna elements of the array system. Simulation results are presented in various signal environments to show the performance of the proposed adaptive algorithm.     

Use of global navigation satellite systems radiation for solving of radar problems

The possibility of using radiation of global navigation satellite systems (GNSS) for the detection of air targets is discussed. Relations for evaluation the detection range are obtained. The requirements for the degree of suppression of the direct signal lights are suggested. The requirements for receiving systems located on the low Earth orbit satellites to overcome the challenges of the global radar are proposed. The range of target detection when simplify signals of backlight pseudolites are used, is received. A bistatic radar system with the backlight pseudolites is presented.     

A novel amplifying antenna array using patch-antenna couplers-design and measurement

This paper proposes a novel amplifying antenna array using the patch-antenna coupler formed by placing one or two open-ended microstrip lines (coupled lines) near and along the nonradiating edge(s) of a patch antenna. An X-band five-element array with broadside 25-dB Chebyshev radiation is demonstrated. When the input signal is fed to the center element, with most of the power radiating from the antenna, part of it is tapped to the coupled lines, amplified by an FET amplifier, and fed to the next antenna element. This process is repeated after all the antenna elements are fed with suitable power. The amplitude distribution of the fields radiated from the antennas is controlled by the coupling coefficient from the patch to the coupled line, which, in turn, is governed by the coupling length and gap between the patch and line. The measured return loss of the designed five-element array is -27 dB at the center frequency of 10 GHz with 2% 10-dB bandwidth. The radiation pattern possesses a transmitting gain of 15.9 dB, a half-power beamwidth of 17/spl deg/, and a sidelobe level of -22 dB.     

卫星导航接收机自适应阵仿真测试评估

卫星导航接收机自适应天线系统能够对消干扰,保证在射频干扰和敌方释放干扰存在的情况下正常提供导航定位功能.为了评估自适应天线的抗干扰能力,必须建立适当的测试环境和测试方法.提出的一种在暗室中进行自适应天线测试的方法,具有保密性好,保证测试环境和外界互不干扰等优点.给出了自行研制的一种导航接收机自适应天线的测试结果.