Far-Field Multicast Beamforming for Uniform Linear Antenna Arrays

The problem of transmit beamforming to multiple cochannel multicast groups is considered for the important special case when the channel vectors are Vandermonde. This arises when a uniform linear antenna antenna (ULA) array is used at the transmitter under far-field line-of-sight propagation conditions, as provisioned in 802.16e and related wireless backhaul scenarios. Two design approaches are pursued: (i) minimizing the total transmitted power subject to providing at least a prescribed received signal-to-interference-plus-noise-ratio (SINR) to each intended receiver; and (ii) maximizing the minimum received SINR under a total transmit power budget. Whereas these problems have been recently shown to be NP-hard, in general, it is proven here that for Vandermonde channel vectors, it is possible to recast the optimization in terms of the autocorrelation sequences of the sought beam vectors, yielding an equivalent convex reformulation. This affords efficient optimal solution using modern interior point methods. The optimal beam vectors can then be recovered using spectral factorization. Robust extensions for the case of partial channel state information, where the direction of each receiver is known to lie in an interval, are also developed. Interestingly, these also admit convex reformulation. The various optimal designs are illustrated and contrasted in a suite of pertinent numerical experiments.     

波导平板裂缝天线阵的设计

利用商业软件HFSS的S参数仿真结果,采用等效网络法对矩形波导宽边纵缝进行互耦环境下的导纳计算;并利用天线远场幅度、相位方向图仿真结果,采用口径场反演方法,对阵中辐射缝参数进行修正。通过设计实例,验证了该方法非常适合于平板裂缝天线阵的设计,有效地提高了设计效率。     

Optimum Ambiguity-Free Directional and Omnidirectional Planar Antenna Arrays for DOA Estimation

This paper studies the antenna array geometry impact on both direction of arrival (DOA) estimation accuracy and array rank ambiguity. Some restrictions are imposed on the array geometry that guarantee first-order ambiguity-free arrays and, at the same time, reduce the cost of a global systematic optimization. The subsequently derived Cramer-Rao bound (CRB) on the DOA estimates shows to be attractive for numerical evaluation. Depending on whether the DOA estimation accuracy is desired to be uniform in all possible directions or is to be enhanced in a given aperture around some privileged direction, two optimization problems are formulated and solved by exhaustive search to compute the optimal array geometries. The obtained optimal arrays significantly outperform their circular counterparts and tend to have a form close to the V shape. We study in details V-shaped arrays and derive asymptotic performance measures that apply for large sized arrays where exhaustive search is unaffordable.     

一种新型毫米波矩形波导-微带过渡结构

介绍了一种新颖的、适用于毫米波频段的矩形波导-微带过渡电路结构。该过渡电路具有插入损耗低、频带宽、重复性好的特性。其矩形波导E面相对于微带电路面,以及电磁信号传输方向的位置与脊波导-微带过渡相同。该过渡电路的微带线与波导的转换部分采用非接触式结构,并设计了可调节元件,从而在有一定加工误差的条件下改善其产品传输特性。利用高频仿真软件CST,在Ka频段进行了优化仿真,并对利用其优化值所设计的一对背靠背的电路实物进行了测试,在32～40 GHz的频率范围内,插入损耗小于2.36 dB,回波损耗大于7.22 dB;在整个Ka频段内,插入损耗小于3.49 dB。     

New Elements Concentrated Planar Fractal Antenna Arrays for Celestial Surveillance and Wireless Communications

This research introduces three new fractal array configurations that have superior performance over the well‐known Sierpinski fractal array. These arrays are based on the fractal shapes Dragon, Twig, and a new shape which will be called Flap fractal. Their superiority comes from the low side lobe level and/or the wide angle between the main lobe and the side lobes, which improves the signal‐to‐intersymbol interference and signal‐to‐noise ratio. Their performance is compared to the known array configurations: uniform, random, and Sierpinski fractal arrays.     

Development of a Broadband Coplanar Waveguide-to-Microstrip Transition With Vias

A transition from coplanar waveguide (CPW)-to- microstrip with vias is often used in wafer-probe measurements. This paper shows how field and impedance matching are used to develop a wideband transition. This paper demonstrates how the presence and placement of the vias affect the bandwidth and alters the impedance of the transition. The measured results on a transition show that a wideband transition with return loss better than 10 dB and an insertion loss less than 1.5 dB up to 36.64 GHz is obtained. The measurements show excellent agreement with simulation. The work presented in this paper provides a better understanding about a CPW-to-microstrip transition with vias as well as design procedures and principles that can be utilized to facilitate the realization of a broadband CPW-to-microstrip transition with vias.      

The Method for the Constructive Synthesis of Planar Antenna Arrays with Consideration of the Interelement Coupling

Journal of Communications Technology and Electronics - The method for the constructive synthesis of planar antenna arrays (AAs) based on the neural network approach with consideration of...     

研制毫米波缝隙天线阵面的技术

对缝隙天线阵面的光刻技术进行了分析,对采用光刻技术方法研制缝隙天线阵面的技 术途径、工艺实验的结果和主要问题进行了论述。毫米波主动导引头缝隙天线阵面,具有面积大、缝隙多、精度高诸特点,能取得了实用价值。     

两种远场测试场天线方向图测试分析

根据天线远场测试理论,结合应用实例,分析了微波暗室和斜天线测试场作为天线远场测试场的适应性。对从 微波暗室和斜天线测试场得到的双脊喇叭天线远场方向图及相关数据进行了分析,总结出两种天线测试场对天线远场测 试影响的特点和规律,并对实际应用提出了指导性建议。     

Out-of-Band Response of Antenna Arrays

The response of antenna arrays to out-of-band frequencies has been analyzed using the effective-aperture approach. An average value of effective aperture can be obtained by averaging the incidence angle and the polarization of the incidence field. Far-field patterns have also been calculated by treating the array element excitations as random variables. The randomness in the element excitations causes a decrease in directivity and an increase in sidelobe level. Out-of-band measurements on a slotted-waveguide array confirm these trends.     

Far-Field Pattern of a Focal-Plane Array-Lens Antenna at Millimeter Wavelengths

In this paper an analysis of the far-field pattern of a focal-plane array in the case of two different lenses, a coma-free lens and a hyperbolic lens, and their comparison, are presented. Ray tracing and aperture integration are used. The calculated field pattern at W band is presented. The focal-plane elements are assumed to be corrugated horn. The f / D of the lens is 1.3. The coma-free lens is designed by step integration. The calculation results show that the coma-free lens is superior to the hyperbolic lens in the imaging performance. The coma-free lens can contain more pixels under the condition that the beam size and beam quality are almost constant over the range of angles scanned and the differences among beams gain less 1.8 dB. The aperture efficiency and directivity are also presented.     

基于压缩感知的天线远场快速测量技术

提出一种应用于天线远场测量系统的压缩感知方法,通过使用正交模拟信息转换(QAIC)结构,可以减少对数据样本的采集,缩短测量时间,并提高天线远场测试效率。为验证系统的准确性,在微波暗室中,测量标准角锥喇叭天线的远场方向图,控制正交模拟信息转换结构的测量数据采样量,低速均匀采样,获取到信号的观测数据,并采用优化算法重构恢复信号。实验表明,该系统在满足一定测量误差的条件下,减少70% 的数据采集量仍能保证测量结果的准确性,较传统暗室测试更高效。     

Mutual Coupling Reduction in Patch Antenna Arrays by Using a Planar EBG Structure and a Multilayer Dielectric Substrate

Periodic structures can help in the reduction of mutual coupling by using their capability of suppressing surface waves propagation in a given frequency range. The purpose of this work is to show the viability of using a planar electromagnetic band gap (EBG) structure based on a truncated frequency selective surface (FSS) grounded slab to this aim. The goal is to use it in patch antenna arrays, keeping both the element separation smaller than for grating lobes avoidance (assuming broadside case) and the patch antenna size large enough to have a good antenna directivity. To this aim, a multilayer dielectric substrate composed of high and low permittivity layers is convenient. This allows the use of a planar EBG structure made of small elements printed on the high permittivity material and, at the same time, the low permittivity layer helps the bandwidth and the directivity of the antenna to be increased. The EBG structure was designed under these premises and optimized for the particular application via an external optimization algorithm based on evolutionary computation: ant colony optimization (ACO). The mutual coupling reduction has been measured and it is larger than 10 dB with a completely planar structure.     

微波毫米波平面共口径天线北大核心CSCD

随着无线通讯和雷达成像等现代无线系统的迅速发展和广泛应用,人们对系统前端的天线提出了更多的需求。共口径天线将多种不同频带或不同功能的天线集成在同一口径,通过在有限口径内对天线单元进行合理布局,显著提高空间利用效率,并在不同天线之间实现高隔离,确保各天线独立工作。根据辐射口径分布情况,共口径天线设计方法可以分为:嵌套技术、交错技术和复用技术。与立体型共口径天线相比,平面共口径天线具有尺寸小、重量轻、成本低、易于集成等优点。本文介绍了微波毫米波平面共口径天线的研究现状,重点介绍了基于交错技术和复用技术的毫米波平面共口径天线,并对共口径天线技术的发展进行了展望。     

Band-Notched Planar UWB Microstrip Antenna with T-Shaped Slot

Ever growing demand for higher data rates requires appropriate radiation systems with large bandwidth and stable gain. Microstrip antennas with unidirectional radiation patterns and stable gain are most useful for this purpose. A ground plane defect of microstrip patch antenna is used to breed multiband applications. As a result, the performance of gain, directivity, and bandwidth is enhanced, the geometry and shape of an ultrawideband (UWB) antenna are simplified, and its size is reduced. Thus, it results in the efficient performance with respect to wideband operation. A novel band notching of microstrip truncated UWB antenna is implemented for insusceptibility in the range 5.2–5.8 GHz. The suggested structure contains circular truncated and T-shaped slots for band notching. The optimal results can be obtained by selecting the antenna parameters. Advantages of the proposed antenna include small size, better impedance match and simple design. Details of the suggested and observational solutions are demonstrated in this paper. The S₁₁ parameter of antenna is–45.5 dB at a resonant frequency of 4.6, 5.5, and 9.8 GHz. The gain of antenna is 5.47 dB, and the value of VSWR is smaller than 2, which makes the proposed structure an ideal choice for its application in wireless communication, 5G and IoT.     

Scattering Characteristics of Ultra-Wideband Antenna Arrays

Journal of Communications Technology and Electronics - This paper presents a study of the monostatic and bistatic radar cross-section (RCS) of three planar two-dimensionally periodic antenna arrays...     

超宽带带阻平面天线的快速化设计

提出了一种小型化,低剖面,同时具有带外抑制(WLAN)的平面UWB天线.该天线包括了一个菱形的辐射贴片,它的工作带宽大约为10GHz,覆盖了3-13GHz的频带,并且在5GHz到6GHz处形成了一个阻带.仿真优化了天线的性能指标包括电压驻波比,辐射方向图和增益.该天线采用的介质基板是FR-4,尺寸为25×35mm,由微带线馈电.该天线很容易和微波电路集成,且制造成本低.最后再通过CAD快速化设计其结构.     

具有双陷波特性的超宽带平面天线设计

设计了一种带有2个陷波频段的超宽带天线。天线的缝隙和馈电枝节采用相反的梯形结构,以实现较好的阻抗匹配。通过在宽缝隙中增加2个线形枝节和1个"E"形结构,使得天线在3.0 GHz~3.9 GHz和5 GHz~6 GHz 2个频段内出现频率阻断。根据天线的阻抗曲线,给出等效谐振电路并对陷波产生的原理进行了分析。最后对天线的远场辐射特性进行分析和阐述,测试结果良好,达到了陷波超宽带天线频率阻断的效果。     

Configurations Optimizing the Directivity of Planar Arrays

The role of the geometrical configuration of isotropic elements in a planar array is investigated with a view to achieve maximum directivity. Distinctions are made between normal and superdirective regions. It is further shown that the configurations leading to optimum directivities may depend on aperture diameter in a manner somewhat analogous to phase transitions in solid state physics. The effect of losses is estimated and it is shown that, particularly for superconductive materials, they do not affect much the achievable gain.     

数字阵列天线远场幅相测试的设计与实现

数字阵列天线的应用是未来军用相控阵雷达最主要的发展方向,数字化的设计带来了更高的系统集成度、更远的作用距离、更丰富的自定义功能等优势的同时,在测试技术层面也带来了诸多改变.本文从数字阵列天线远场测试的角度介绍幅相测试的方法、系统测试设计原理,并针对实际工程应用提供具体实现方式.实际测试结果表明这些方法和实现方式有效,对...