大规模MIMO相关信道下的联合天线分组和天线选择

在大规模多输入多输出系统中,针对密集部署的大型天线阵列之间的强相关性会抑制天线选择增益效果的问题。在系统下行链路场景下建立空间相关信道模型,提出了基于天线分组的天线选择算法。根据瞬时信道相关矩阵将天线阵列划分为若干组,保证各组内天线之间相关性较强。在完成天线分组的基础上,基于信道矩阵列范数准则在各组发射天线与接收天线之间构成的子信道矩阵中选择天线,进而构造有效发射天线与接收天线之间的信道矩阵。仿真分析了所提天线选择算法对系统遍历和速率的影响,结果表明,在基站天线数为32、接收天线数为2、选择天线数为2、天线相关因子为0.9的假设下,当信噪比为10 dB时,与基于相邻天线分组的天线选择算法相比,所提算法使系统和速率约提高了27.5%,且所提算法若要与最优天线选择算法达到相同的和速率,仅需将其信噪比提升1～2 dB即可。     

多根细线天线对超宽带信号的瞬态响应特性

利用FDTD(时域有限差分)方法对多根未加载的细线天线以及加载的细线天线瞬态响应特性进行了数值模拟。分析了其他细线天线的存在对馈源为电磁脉冲的细线天线辐射特性的影响以及入射波为电磁脉冲时细线天线中心的电流响应特性的影响。指出了在确定天线是否相关时,天线之间的距离所应当满足的条件。     

一种多功能反射面天线的设计

介绍了一种多功能反射面天线的设计方法,利用同一反射面实现跟踪和干扰的功能。跟踪采用副面为栅条形式的卡塞格伦天线,干扰采用前馈抛物面天线。2种天线正交极化,通过理论计算、仿真优化结合合理的结构设计,保证2种天线的电性能及相互之间的隔离度。     

Design of a compact planar wide band antenna family

A new family of compact planar wide band antennas is proposed. These simple and planar antennas have stable omnidirectional patterns and flat gain in the whole of bandwidth. Five types of these antennas are designed and simulated to clarify the ability of these introduced antenna family. Also, one of these antennas is fabricated and tested. The simulation and the measurement results are in good agreement. The measurement results show that this antenna works between 1.91 and 5.25 GHz (93.3% bandwidth) and it has a very compact dimensions. Also, the antenna analysis results show that the antenna center frequency and bandwidth can easily controlled by changing the scale factor and section factor, respectively. Finally, the antennas comparison results with the references verify the capability and power of them.     

一种MIMO智能天线融合方法研究

提出一种采用波束调度策略的MIMO与智能天线融合设计方案,用以解决MIMO传输中空域相关性问题。融合方案在天线结构上以智能天线单元组建MIMO阵列,智能天线单元之间协同工作。分析了采用波束调度时的MIMO矩阵构成及其合并接收方式,给出一种波束间空域相关性的计算方法。仿真结果表明,在小角度扩展条件下,同指向的波束相关性与全向阵元相关性相似,而波束调度策略具有良好的去相关性,能有效提高MIMO信道容量。     

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。     

Metamaterial-Inspired Efficient Electrically Small Antennas

Planar two-dimensional (2D) and volumetric three-dimensional (3D) metamaterial-inspired efficient electrically-small antennas that are easy to design; are easy and inexpensive to build; and are easy to test; are reported, i.e., the EZ antenna systems. The proposed 2D and 3D electrical- and magnetic-based EZ antennas are shown to be naturally matched to a 50 source, i.e., without the introduction of a matching network. It is demonstrated numerically that these EZ antennas have high radiation efficiencies with very good impedance matching between the source and the antenna and, hence, that they have high overall efficiencies. The reported 2D and 3D EZ antenna designs are linearly scalable to a wide range of frequencies and yet maintain their easy-to-build characteristics. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions. The EZ antennas systems may provide attractive alternatives to existing electrically-small antennas.     

Broadband quasi-microstrip antenna

A new printed microwave antenna is presented. The antenna is a hybrid between a wire antenna array and a microstrip patch antenna. Although the size, cost, and efficiency are comparable to the microstrip patch, the voltage standing wave ratio 2:1 bandwidth of the antenna presented here is above 20%. The radiation pattern of the antenna does not change appreciably within the bandwidth, and the theoretical efficiency for optimal antennas remains above approximately 80% within the bandwidth. Measurements on several antennas around 2 and 4 GHz are presented, as well as theoretical results obtained using a full-wave analysis     

Decoupling and descattering networks for antennas

The possibilities of connecting a lossless network between input ports and antenna ports such that there is no coupling and scattering between the antennas are discussed. A necessary condition for complete decoupling and descattering is power orthogonality between the patterns of the individual antennas. Numerical and experimental results are presented for monopole antennas.     

探地雷达超宽带背腔蝶形天线设计与实现

设计实现了一种中心频率为400 MHz的吸波材料填充式背腔蝶形天线,并将此天线应用于超宽带探地雷达系统,组装完成了一套400 MHz无线控制探地雷达系统样机。背腔式设计的探地雷达收发天线可以克服传统蝶形天线在H面全向辐射所带来的缺点,从而提高雷达系统的信噪比及收发天线之间的隔离度。对背腔蝶形天线的设计进行了规律性研究,总结了吸波材料填充式背腔蝶形天线系统在工程化实现时的设计经验。实际路测数据验证了所设计背腔天线在此套探地雷达系统中性能表现稳定良好。     

Calculation of Site Attenuation from Antenna Factors

A site-attenuation model expressed in terms of the antenna factors of the transmit and receive antennas is presented. Both horizontal and vertical polarizations are included, as are the effects of mutual coupling between closely spaced horizontal antennas. Expressing site attenuation in terms of antenna factors allows the use of broad-band antennas with their attendant advantages over tunable dipoles. Measured and calculated results for a variety of sites, antennas, and geometries are compared in the frequency range of 30 MHz to 1 GHz.     

一种710MHzLTE天线的去耦合分析

为了提高天线的容量和发射接收速率,LTE通信系统使用了MIMO天线。由于移动终端上空间有限,多个天线间存在较大耦舍,天线的辐射效率和通信容量会降低。为了解决这一问题,从S参数的角度推导出了天线的正交辐射模式,提出了通过加入180。耦舍器来降低多个天线间耦合的方法。使用HFSS和ADS对设计好的710MHz天线进行联合仿真,结果显示加入耦舍器后,两个天线间的耦合明显减小。这种设计使得该天线可以很好地应用于LTE通信系统的移动终端。     

Broadband dual-polarized patch antennas fed by capacitively coupledfeed and slot-coupled feed

Designs of broadband dual-polarized patch antennas fed by promising feed structures of a capacitively coupled feed and a slot-coupled feed (antenna A), two capacitively coupled feeds of a 180° phase shift and a slot-coupled feed (antenna B), and two capacitively coupled feeds of a 180° phase shift and two slot-coupled feeds (antenna C) are proposed and experimentally studied. The first two feed designs are for the excitation of a single-element broadband patch antenna, while the last design is for a two-element broadband patch antenna. These proposed patch antennas have a thick air substrate, and the 10 dB return-loss impedance bandwidths obtained for the two polarizations are all greater than 13%. High isolation (<-30 dB for antenna A, <-32 dB for antenna B, <-35 dB for antenna C) between the two feeding ports for the entire impedance bandwidth of the proposed antennas can be obtained. Also, improved cross-polarization levels (>20 dB) in both E and H plane patterns for the two polarizations of antennas B and C are achieved     

A unidirectional semi-circle spiral antenna for subsurface radars

Specifications of an antenna for a subsurface radar are quite different from those of an ordinary antenna for telecommunication. The antennas for a subsurface radar are located very close to the interface between the air and the Earth's surface. The antennas for subsurface radars have mutually conflicting requirements such as low-frequency operation for better penetration, broadband characteristics for finer resolution, small size for pinpointing the antenna location, and sufficient sensitivity for good signal-to-noise ratio of the image. It is found that a semi-circle spiral antenna with a cylindrical waveguide can meet most of the above requirements. A practical structure is proposed, and a method of designing such an antenna is presented. The experimental results show the usefulness of the developed antenna     

SOP integration and codesign of antennas

The successful deployment of wireless systems requires the integration of small, cost-effective antennas while preserving a reasonable electrical performance in the required bandwidth. This paper begins with a short overview of the most important antenna characteristics, and then uses these to describe the minimum requirements and fundamental performance-size limits for electrically small integrated antennas. The performance-size tradeoff is further illustrated by the design of a planar integrated antenna for WLAN. Codesign guidelines are given to avoid parasitic coupling between the integrated antenna and RF circuits. A concluding comparison is made between on-chip and on-package integration of a small antenna for microwave and millimeter wave systems.     

飞机V形尾翼共形垂直极化合成天线

共形天线因其低剖面特性被广泛应用于现代飞行器中,垂直极化天线也是现代通信系统中最为简单经济的天线形式.基于目前天线设计中少有通过极化合成实现垂直极化特性的方法,提出一种与V形尾翼共形且具有垂直极化特性的合成天线,给出了以对称振子为合成单元的闭环解析公式,该公式可应用于任何角度、任何距离、任何激励的天线组合形式.通过HF...     

密距八木天线的设计与仿真

介绍了应用密距原理设计的密距八木天线,采用T形匹配天线来代替传统的用于激励器的折合振子和用于反射器及引向器的半波偶极子,通过减小T形匹配天线之间的距离来实现天线的小型化设计。以中心频率为500 MHz密距八木天线为例,说明了天线的设计过程,设计结果表明,该天线具有较为理想的技术指标,同时,相对于传统的八木天线,该设计使天线尺寸明显减小。     

Antenna diversity in mobile communications

The conditions for antenna diversity action are investigated. In terms of the fields, a condition is shown to be that the incident field and the far field of the diversity antenna should obey (or nearly obey) an orthogonality relationship. The role of mutual coupling is central, and it is different from that in a conventional array antenna. In terms of antenna parameters, a sufficient condition for diversity action for a certain class of high gain antennas at the mobile, which approximates most practical mobile antennas, is shown to be zero (or low) mutual resistance between elements. This is not the case at the base station, where the condition is necessary only. The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.     

TD-SCDMA系统中一种软件集成智能天线算法

给出了一种采用信干噪比准则的、集成了预多波束天线与LMS自适应天线的软件天线方案,该方案采用开关合并方法,把软件天线输出接到最大输出信噪比的算法输出,实现算法分集.在TD-SCDMA动态模型上对提出的方法进行了仿真,结果表明,采用集成软件天线方案的误码率性能要优于单纯的预多波束天线或LMS自适应智能天线.仿真过程考虑了用户来波方向和用户到基站距离的动态变化,以及功率控制算法和系统同步过程的影响.     

Antennas for VHF/UHF personal radio: A theoretical and experimental study of characteristics and performance

A theoretical analysis of the characteristics of small personal radio antennas for the 68- to 470-MHz frequency range is given. Representing the human body by a simplified lossy dielectric structure, the influence of the body on the performance of the antenna is investigated in detail, and it is shown how antenna impedance, gain, and radiation patterns can be calculated taking the presence of the body into account. For very short antennas the results indicate that radiation from the body may dominate over the radiation contributed by the antenna itself, and that the presence of the body can increase the antenna efficiency considerably, indicating that even very short antennas may provide acceptable radiation efficiencies. The results of the theoretical work are supported by measurements on practical antennas. Quarter-wave and short antennas of the helical type are compared with respect to efficiency and radiation patterns at 80, 160, and 450 MHz, and it is demonstrated how the physical length of the antenna affects the antenna performance. The design of a very short and compact personal radio antenna is described.