共查询到19条相似文献,搜索用时 765 毫秒
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采用无色散特性的模拟或数字移相器会导致天线波束指向随频率发生变化,即相控阵天线的孔径效应。工程上一般在子阵级别上采用色散特性的实时延迟线拓展相控阵天线瞬时带宽,但是子阵级延时量化误差会产生周期性栅瓣,导致天线副瓣性能恶化。文中提出在通道(或多通道收发组件)上设置小位延迟线、与子阵级大位延时线叠加使用,消除或改善子阵级延时误差造成的性能恶化。结合X波段有源二维阵列天线,对单元级、子阵级、子阵+单元两级三种情况进行了仿真。仿真结果表明,子阵+单元两级延时方法在扩展相控阵天线瞬时带宽的同时,能明显改善相控阵天线的副瓣特性,且具有较强的工程可实现性。 相似文献
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多子阵平板天线波束指向频率响应分析与固定长度延迟线应用 总被引:1,自引:0,他引:1
天线高度是宽带卫星移动通信系统推广应用的一个重要制约因素,采用多子阵技术可以降低平板天线的天线高度。然而多子阵平板天线阵的离散口径会造成天线波束指向频率响应的恶化。为改善天线波束指向频率响应,该文采用固定长度延迟线与移相器相结合的两级馈相方法,提出了一种基于多套延迟线的切换波束技术,将天线波束的扫描范围划分为多个区域,各区域采用不同的延迟线以合成相应的波束。仿真结果表明,该方法可以有效减小天线波束指向漂移,满足卫星移动通信系统对天线波束指向精度的要求。 相似文献
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采用矢量调制器作为新型有源相控阵的核心器件,替代传统的波束成形单元中数字移相器和数字衰减器。分析了矢量调制器幅度相位的调制原理,从数学上推导出幅度调制系数和相位调制之间的关系。与数字移相器相比,它不但能够同时进行幅度和相位调制,还具有更加精确的调制精度。设计研制了8×8小型相控阵天线系统,介绍了相控阵系统的构成。通过闭环校准技术对相控阵的通道误差进行了测试和补偿,有效地降低了方向图的副瓣。最后测试结果显示在矢量调制器的控制下,研制的有源相控阵在E面和H面两个方向上具有±40°的波束扫描能力,副瓣抑制优于-10dB。 相似文献
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在相控阵天线中,应用具有随机相位反转的等幅单元产生有效的锥削幅度分布,以降低副瓣的新颖方法在本文的第一部分中已作了叙述。它是改变某些移相器的第一位数字并使其叠加到控制波束的相移上。如果把一位相位加权的方法加以扩展,使用只有两位的移相器,那么就可以同时控制波束和应用一个有效的锥削幅度分布。这种方法既能降低第一副瓣(通过锥削),又能降低由于使用仅有两位移相器控制波束所引起的寄生副瓣。由于随机过程的方差增大,峰值副瓣电平并没有达到象一位相位加权的副瓣电平。对于128个单元的天线阵,其峰值副瓣电平达到-15.6分贝,而256个单元的天线阵的峰值副瓣电平则达到-17.4分贝。 相似文献
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为了对随机相位误差对于相控阵天线波束指向精度和副瓣电平的影响进行分析,以一维均匀直线阵为模型,采用概率统计的手段对波束指向误差的数学期望、方差和峰值副瓣电平进行了推导,并对此结果进行了计算机仿真验证和比较.仿真结果表明,理论公式推导得到的结论与仿真实验的各项结果吻合良好. 相似文献
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相控阵天线是天线领域的重要课题,其波束快速灵活的优点命名其得到了广泛的应用。相控阵天线能极其迅速地改变波束的指向,关键在于相控阵天线每个单元的电调移相器。而如何控制移相器的配相方法使得天线获得最佳的性能就成为实际应用中必须研究的课题。 相似文献
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A potential application of MSW technology lies in the area of time delay for future low-sidelobe wide-bandwidth phased array antennas. High-precision MSW electronically tunable analog time-delay units in transmit/receive modules in phased arrays have the potential of greatly enhancing antenna system capabilities, by increasing instantaneous operating bandwidth and decreasing sidelobe levels, over phased array systems using only phase shifters or switched lines for beam steering and control. This paper provides a status report of MSW time delays for such arrays. 相似文献
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研究了宽带数字阵列雷达真延时(TTD)步进精度与最大天线副瓣电平的关系,通过分析将TTD步进精度等效为移相器的量化误差,并据此提出了一个TTD步进精度与最大天线副瓣电平之间的估算公式。仿真结果表明,提出的估算公式能够较为准确地估计出TTD步进精度,可为宽带数字阵列雷达设计具有超低副瓣天线方向图提供参考。 相似文献
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Byung-Min Jung Jong-Dug Shin Boo-Gyoun Kim 《Photonics Technology Letters, IEEE》2007,19(12):877-879
An optical true time-delay (TTD) scheme for two-dimensional (2-D) X-band phased array antennas (PAAs) has been proposed. It is composed of a multiwavelength optical source and a delay line matrix consisting of 2times2 optical microelectromechanical system (MEMS) switches with fiber-optic delay lines connected between cross ports. A 2-bit times 4-bit optical TTD for 10-GHz 2-D PAAs has been implemented by cascading a wavelength-dependent TTD (WD-TTD) with a unit time delay of 12 ps in the x-direction and a wavelength-independent TTD (WI-TTD) with that of 6 ps in the y-direction. The time delay error for WD-TTD was measured to be less than 2.8 ps, mainly due to jitter incurred from gain-switching. On the other hand, the error for WI-TTD was less than 0.8 ps, which is within the equipment resolution. Insertion loss of both delay line matrices was less than 1 dB due to the column-wise control of the MEMS switches. This prevents the feed current applied to each antenna element from fluctuating at any radiation angles so that antenna gain and sidelobe level do not deteriorate in this scheme 相似文献
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In conventional phased array radars, analogue time delay devices and phase shifters have been used for wideband beamforming. These methods suffer from insertion losses, gain mismatches and delay variations, and they occupy a large chip area. To solve these problems, a compact architecture of digital array antennas based on subarrays was considered. In this study, the receiving beam patterns of wideband linear frequency modulation (LFM) signals were constructed by applying analogue stretch processing via mixing with delayed reference signals at the subarray level. Subsequently, narrowband digital time delaying and phase compensation of the tone signals were implemented with reduced arithmetic complexity. Due to the differences in amplitudes, phases and time delays between channels, severe performance degradation of the beam patterns occurred without corrections. To achieve good beamforming performance, array calibration was performed in each channel to adjust the amplitude, frequency and phase of the tone signal. Using a field-programmable gate array, wideband LFM signals and finite impulse response filters with continuously adjustable time delays were implemented in a polyphase structure. Simulations and experiments verified the feasibility and effectiveness of the proposed digital beamformer. 相似文献
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Dau-Chyrh Chang Chang-Nan Hu Chia-I Hung Ko-Tai Ho 《Antennas and Propagation, IEEE Transactions on》1994,42(2):240-245
The performance degradation of an offset reflector antenna with off-axis scanning feed and distorted reflector surface can be improved by using a phased array feed. Generally, both analog attenuators and phase shifters are used in phased array feed. Yet, it seems to make the feed system very complicated. In this paper, a phase-only gradient search (POGS) algorithm is developed to optimize the performance of offset reflector antenna systems using phased array feed that is equipped with phase shifters only. This technique not only can greatly simplify the complexity of phased array feed, but also can provide the reflector antenna with better antenna gain and sidelobe level control capability. Simulation and experimental results are presented to illustrate the excellent performance of offset reflector, with limited beam scanning capability, can be obtained by using this less complicated phased array feed 相似文献
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Gordon R. Harrison Thomas E. Sharon 《Journal of Infrared, Millimeter and Terahertz Waves》1988,9(5):443-468
Many present and future military and commercial systems operating at millimeter wave frequencies require the use of sophisticated electronically controllable antennas for maximum capability and flexibility. Electronic control of the antenna pattern is provided by electronically switchable phase control of each radiating element such as that achieved in phased array antennas or via electronically reconfigurable antenna feeds referred to as beam forming networks (BFN). Multibeam antennas provided by BFN'S can be realized using switches, variable power dividers (VPD), and phase shifters. Ferrite materials and associated application technology are being utilized to achieve these switchable RF control components at millimeter wave frequencies. The performance achievable in ferrite switchable circulators, variable power dividers and phase shifters in the frequency region from 20 to 100 GHz is discussed. 相似文献
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Bodnar D.G. Rainer B.K. Rahmat-Samii Y. 《Vehicular Technology, IEEE Transactions on》1989,38(2):86-94
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 相似文献