数字阵列天气雷达低副瓣天线设计

为天气雷达设计一维相扫相控阵天线,方位面副瓣低于-30 d B,波束宽度小于1°,俯仰面接收副瓣低于-40 d B。方位面波束采用窄边波导裂缝阵列天线实现,采用全数字T/R组件精确控制幅度和相位,实现低于-40 d B的俯仰面接收副瓣。测试结果表明,副瓣电平与波束宽度指标与理论值吻合较好,满足指标要求。     

A switched pattern radar antenna array

A procedure to design a switched pattern antenna array is developed and demonstrated on a 16- and eight-element array. The variable spacing of elements allows us to reduce the number of switchable elements to a minimum and to reduce the sidelobes of the effective pattern. Based on this design we have built and tested an eight-element prototype array. Measurements demonstrate the feasibility of the pattern switching concept for improved sidelobe performance.     

Wideband microstrip array antenna with sidelobe cancellationchannels

An antenna array for wideband operation (up to 70%) is presented. The structure has low windloading area and consists of parallel printed circuit boards (PCB) with microstrip dipoles, feed network and metal fences placed between the PCBs. The low profile, low weight antenna array forms the main beam and three difference patterns for sidelobe cancellation. Experimental results are compared with calculations for both microstrip dipole and array     

Reduced sidelobe four-beam antenna array fed by modified Butler matrix

A novel four-beam antenna array fed by a modified 4/spl times/8 Butler matrix is proposed. Four 180/spl deg/ directional couplers in conjunction with a 4/spl times/4 Butler matrix are applied to provide a tapered excitation of a linear eight-element switched-beam antenna array. Sidelobes as low as -20 dB for all four beams have been both theoretically and experimentally achieved. A proposed technique of antenna element rotation simplifies the design of a feeding network.     

随机误差对模块化阵列天线副瓣的影响

推导了相位误差、单元位置误差和子阵位置误差的取值范围与模块化阵列天线副瓣累积概率的关系,以及单元位置误差、子阵位置误差与整体位置误差的关系.通过实例说明,激励幅相误差、单元位置误差和子阵位置误差,对实现超低副瓣都是至关重要的.     

L波段双脊裂缝波导低副瓣阵列天线的设计

设计了一种L波段双脊波导裂缝阵列天线。该天线具有好的频率响应特性,实现了低副瓣,水平垂直两个面的交叉极化得到了有效抑制。由于馈电双脊波导的截面尺寸大幅度减小,使得这项研究将有很好的应用前景。     

Alternative approach to designing array pattern with controlled mean-square sidelobe level

A more general and efficient approach for designing array patterns with a controlled mean-square sidelobe level is presented. It is shown that the approach presented by Ng (see ibid., vol.26, p.337-9, 1990) can be considered as a limiting solution to the quadratic constrained optimisation problem presented in this Letter. Numerical results showed that under high interference-to-white noise ratio conditions, the new approach performs better, on average, than the Chebyshev synthesis technique.<>     

Wide-frequency-band radar array antenna system with suppressed grating lobes

When array antennas are used for wide-frequency operation a difficulty with grating lobes is encountered at the upper frequency end of the operating band. This paper points out that the use of arrays for transmission and reception with different interelement spacings can be used to extend the operating frequency band in a radar system. The principle of transmitting-receiving arrays with different illuminations was used by Mattingly [2] to lower the sidelobe level of a radar array antenna. Birge [3] used it to reduce the number of elements in an array while preserving the resolution. The same principle is used in this paper to extend the operating frequency bandwidth of a radar antenna system. Relationships for an optimized radar array antenna system are derived. The criterion for optimization is the maximum bandwidth with a given total number of elements. It is shown that in an optimized system the number of elements in one array antenna is one greater than in the other, and the ratio of interelement spacings is inversely proportional to the square of the number of elements in the respective arrays. Based on these conditions, a functionkis computed and tabulated. This function determines the number of grating lobes permissible in the specified angular sector, without overlap, as a function of the number of elements in the two arrays. An application to a high frequency (HF) ionospheric radar antenna system, now under construction, is used as an illustration of the principles outlined in the paper.     

Cramer-Rao bound analysis for active array with antenna switching

An active radar array with antenna switching provides information on the direction, velocity and range of multiple-targets, in which the receiving antennas are switched to the single receiving channel periodically. The Cramer-Rao bound expressions for estimating the movement parameters using the radar system are derived.     

Realizable method of pattern synthesis for array antenna

The problem of realization of an arbitrary current distribution on an broadside array antenna derived from the theory of pattern synthesis is treated and some practical methods are proposed. In these methods, the input voltage of each antenna is transformed by a reactive transformer to take the required value. In one of the methods, experiments to yield Chebyshev patterns were performed and satisfactory results were obtained.     

某型雷达对称振子阵列天线的设计与仿真

文中基于某型号雷达天线参数的设计指标,采用阵列天线的经典理论和泰勒综合法设计出符合要求的IX28阵列天线.并且还对阵列天线的阵元选择和设计,添加反射板和阵元间互耦等问题进行了研究.通过电磁场仿真软件HFSS进行了仿真试验,得出文中所设计的L波段对称振子阵列天线符合设计要求的结论.     

风廓线雷达有源相控阵天线研究

风廓线雷达有源相控阵天线可以显著避免来自地杂波的干扰,非常适用于气象领域。文章从系统整体设计、天线辐射模块方案、收发单元的设计、功放单元的设计、天线阵的设计等方面详细阐述了此种天线的研发过程。     

Carrier-to-noise ratio and sidelobe level in a two-laser modeloptically controlled array antenna using Fourier optics

The carrier-to-noise ratio of the microwave signal and the reduction of the antenna sidelobe are discussed for an optically controlled array antenna whose microwave aperture distribution is generated and controlled using Fourier transform and optical/electrical conversion. A two-laser model using two laser diodes whose frequency difference is set to the desired microwave frequency is proposed and compared with a single-laser model using an external modulator. The two-laser model seems to be favorable from the viewpoint of available laser diode output power. The required laser output for the two-laser model can be about 10 dB less than that for the single-laser model. Moreover, relationships between the antenna radiation characteristics and the aperture size of an image mask are investigated. It is clarified that the sidelobe level can be reduced about 20 dB without changing the gain and beamwidth by using a reference optical beam with a tapered amplitude distribution     

Arbitrary antenna array pattern synthesis using minimax algorithm

A novel approach to arbitrary array pattern synthesis is proposed. It is based on the minimax algorithm originally developed for mismatched filter design for radars with pulse compression. The proposed approach allows the user to define the pattern mainlobe beam width and the sidelobe envelope shape     

Directional borehole radar with dipole antenna array using optical modulators

In this paper, we describe a directional borehole radar comprising a dipole antenna array with an optical modulator capable of determining the position of targets in three dimensions (3-D). Optical modulators using a Mach-Zehnder interferometer are used to transform electrical signals into optical signals at the feeding points of the dipole antennas. The advantages of using these modulators are that we can easily arrange the dipole antennas in a borehole, and that we can expect a good agreement between the experimental data and a theoretical model representing the array. We have made a prototype borehole radar system with five dipole antennas for the reception. In order to model the antennas, we used the method of moment (MoM), utilizing a modified Green's function for dipole antennas in multiple cylindrical layers. The Green's function is evaluated analytically by numerical integration. Cross-hole and single-hole measurements were carried out in granite at the Kamaishi mine (Iwate, Japan), and we obtained good agreement between the experimental data and the MoM results. After applying superresolution techniques to the data received by the array, we estimated the 3-D scattering position of a geological interface in granite. The results were in fairly good agreement with borehole scanner images.     

粒子群优化算法用于阵列天线方向图综合设计

粒子群优化算法是基于一群粒子的智能运动而产生的一类随机进化算法,其优点是算法非常利于理解和应用.本文介绍了粒子群算法的原理和流程,研究了如何将这种方法运用于天线阵的方向图综合上,给出了PSO算法在综合阵列方向图的应用实例,表明粒子群算法在天线阵列综合中具有广泛的应用前景.     

一种贴片阵列天线散射减缩的新技术

引入贴片天线单元渐变开槽的方式来设计低散射阵列天线.通过对不同的单元开不同尺寸的槽,在等幅度馈电的情况下实现远区辐射场的低副瓣特性.对开槽贴片单元进行散射减缩预估,然后将该方法应用于1×9渐变开槽贴片阵列的设计中,与传统阵列天线的单元形式完全一样,采用不等幅馈电实现泰勒远区辐射场相比,该方法不仅实现了远区辐射场的低副瓣,而且实现了天线模式项散射场的低副瓣,同时又兼顾了结构模式项散射场的散射减缩,从而有效地实现了阵列天线的低散射特性.测量结果与原始阵列进行比较,证明了该方法的有效性.     

Optimization with controlled null placement in antenna array pattern synthesis

The optimal solution to the problem of minimizing the complex weight vector norm subject to a "look direction" and null constraints in array pattern synthesis is given. It is also shown that several constrained optimization problems in pattern synthesis, viz, constrained maximization of signal-to-noise ratio (SNR), constrained pattern gain maximization, and constrained least squares pattern synthesis are, in fact, equivalent. Reduction of the maximum gain in the look direction and the occurrence of main-lobe angular shifts which are inherent in constrained pattern synthesis are also investigated.     

Linear antenna array pattern synthesis with prescribed broad nulls

A technique of synthesizing an antenna array pattern with prescribed broad nulls is presented. The array pattern synthesis problem is formulated as a least-square null constrained optimization problem. Numerical techniques based on the matrix factorization method are developed for reducing the computational complexity of determining the optimal weight vector. Subsequently, a set of eigenvector constraints are used to approximate the effect of the quadratic constraint. Numerical results are presented to illustrate the performance achievable