智能天线教学实验系统的实现

智能天线是移动通信系统中广泛采用的一种新技术.本文主要介绍在移动通信实验箱中增加智能天线实验功能时对智能天线阵列类型、下行波束赋形、上行波束成形和天线校准等关键算法的选择以及智能天线教学实验系统的整体实现方案.由于实验系统可对信道环境等实验条件做适当简化,因而可以通过合理设计,在不影响实验效果的前提下,降低实验系统的复杂度和成本.     

一种2.45GHz频段RFID读写器天线

2.45 GHz频段是RFID常用的频段之一,针对该频段的一款读写器天线进行了详细的分析并进行了改进。借助ANSOFT HFSS 10.0计算软件对天线系统进行了仿真分析,在样本天线的基础上,通过对贴片边缘开槽,使天线在保持高增益的情况下,在更宽的频带上具有更好的稳定性,同时也减小了天线的尺寸,使天线整体性能更加完善。     

60GHz室内天线位置优化与天线选择策略

采用多天线技术的60 GHz无线通信被认为是未来室内场景下高数据率宽带无线接入一种有前途的解决方案。参考802.11ad工作小组采用的60 GHz信道模型,根据60 GHz路径损耗公式提出的分布式天线系统间距的优化方案可以保证房间内功率覆盖的均匀性。在此基础上,进一步分析60 GHz多天线系统在不同链路条件下的信道条件数关系,提出一种基于信道条件数的天线选择策略。该策略利用信道条件数判断信道性能,既保证了通信质量,又适时降低系统总功率,切换简单、易于操作,适用于60 GHz室内无线通信。     

一种工作于1.6 GHz ~20 GHz 的高增益对跖Vivaldi 天线

设计了一款工作于1.6 GHz ~20 GHz 的高增益对跖Vivaldi 天线,该天线在常规对跖Vivaldi 天线的左右两端加载半椭圆贴片结构,改善低频驻波比特性,进而提高了天线的阻抗带宽;在天线主轴方向加载梯形基板,将天线表面电场约束在天线的主轴方向上,不但消除了天线增益峰值的偏移问题,而且提高了天线的增益值。实测结果表明:该天线在1. 6 GHz ~20 GHz 频段内电压驻波比小于2,增益为1. 5 dB ~11. 1 dB。此外,该天线增益峰值偏移现象得到明显抑制,具有辐射方向性好、增益高、交叉极化比小的优点。     

智能天线在TD-SCDMA系统的实现

研究智能天线在TD-SCDMA系统中的实现,详细介绍了该系统所采用的算法(最大功率合成算法)以及采用这种算法所具有的特点。通过对容量、覆盖范围和误码率等方面的具体分析,探讨了智能天线对TD-SCDMA系统性能的改进。最后仿真出该系统在不同业务下的误码率和误块率,由仿真结果可以明显地看出,采用智能天线可以极大地改善系统的性能。     

智能天线的波束形成算法与实现

提出了一种基于遗传算法的波束形成方法。该方法具有很好的收敛性,与传统的LMS算法相比,遗传算法具有良好的全局搜索能力,对于复杂的搜索空间,能快速地找到最优解。利用FPGA进行空域滤波,通过DSP浮点运算,高效地实现权值估计,避免高位加法进位影响权值速度,使得智能天线波束形成算法的实现简便易行。     

Interference Analysis in an Urban Mesh Network Operating in the 60‐GHz Band

Because of their exclusive features, millimeter wave directive mesh networks can be considered for small cell backhaul support in urban environments. For this purpose, a network of closely spaced stations has been considered with very directive line‐of‐sight links operating in the 60‐GHz band. An attempt is made to evaluate channel response and interference behavior in such a network, taking into account the effect of building blockage. A simple grid of building blocks is considered as the propagation environment, and wave propagation is simulated using 2.5‐dimensional (2.5D) ray tracing (2D with ground effect) to calculate the received signal at different nodes in the network. The results are compared with free space predictions and used to evaluate interference at all nodes in the channel and describe certain characteristics of links, such as the delay profile and the correlation length.     

多屏互动技术在智能电视操作系统中的实现

随着三网融合的逐步推进以及网络技术的不断发展,数字家庭网络也从概念走向了前台,其中使用多屏互动技术实现家庭娱乐信息共享是数字家庭网络中一项非常重要的内容。本文在深入研究DLNA体系架构和功能组件的基础上,结合智能电视操作系统的特点,提出了在智能电视操作系统中实现多屏互动技术的一种解决方案,满足用户在智能手机、个人电脑和智能电视之间完成视频、音频及图片等多媒体资源的管理、控制和共享需求。     

GPS中智能天线的设计与实现

目前对智能天线的研究主要侧重于智能天线的自适应波束形成算法和智能天线的应用两个方面,并已提出了不少高效的智能天线算法,智能天线的理论已经很成熟。对智能天线应用研究最多的是它在第三代移动通信中的应用。文中提出智能天线在GPS(全球定位系统)中的一种应用方案,它基于功率倒置算法,用DSP实现。     

智能天线自适应波束的形成与实现

智能天线利用数字信号处理技术，产生自适应定向波束，使天线主波束对准用户信号到达方向．旁瓣或零陷对准干扰信号到达方向，达到抑制干扰，提高移动通信系统容量的目的。文章研究了自适应波束形成的基本原理及其FPGA实现过程。     

Antenna Tests With a Hologram-Based CATR at 650 GHz

A hologram-based compact antenna test range (CATR) is designed, constructed, and used to test a 1.5-m antenna at 650 GHz. The CATR is based on a 3.16-m-diameter hologram as the collimating element. So far, this is the highest frequency at which any CATR has been used for antenna tests. The quiet zone is measured and optimized before the antenna tests. The measured antenna pattern results at 650 GHz are analyzed and compared to the simulated patterns. Feed scanning antenna pattern comparison technique is used to correct the antenna pattern. These tests show the hologram CATR to be promising for antenna measurements up to 650 GHz.     

Radio-Optical System Design and Transmission Experiments for a Mobile Broadband Communications System at 60 GHz

The paper presents the system designconcept for a mobile broadband communications systemat 60 GHz. A dense WDM system is used for the opticalbackbone employing novel add/drop multiplexers. Forsimplicity, there is no signal processing andfrequency generation at the base station and a masteroscillator signal are used for millimetric carriergeneration. The master oscillator signal is modulatedonto the optical carriers by a novel concept ofsimultaneous external modulation, simplifying systemdesign significantly. Transmission experiments over acomplete downlink path using uncoded 2-FSK have beencarried out and a BER of 10^-9at 50 MBit/s hasbeen obtained. Furthermore, 512-carrier DQPSK-OFDMtransmission at 45.8 MBit/s using 35 MHz bandwidth at60 GHz has been demonstrated.     

一种P波段宽带端射天线设计

设计了一种P波段的宽带端射天线。该天线以传统八木天线为基础,将振子尺寸缩小为原来的一半,并将振子放置在金属平板上,进而对天线的反射器和引向器进行改进,并通过对天线参数的仿真优化,最终将天线的带宽扩展到了38.4%,并保证了频带内相对较高的增益。仿真结果表明,天线能够在0.5~0.8 GHz的频带之内实现良好端射,并保证带内回波损耗均在-10 d B以下,整个频段内天线的方向性系数均在8.6 d Bi以上。     

2.4GHz ISM频段平面印刷T型单极子天线的研究与设计

研究用于2.4GHzISM频段共面波导馈电的T型单极子天线。在T型天线水平臂和垂直臂的长度和宽度的四种组合情况下,给出了输入驻波比带宽的变化曲线图,并分别设计了两个(1#和2#)天线,其结构简单紧凑,且不带底板,易于集成和平面印刷。实测结果表明:在2.4GHz频段上,1#和2#天线分别获得了12.24%和16.33%的相对带宽(VSWR≤2)。     

20, 30 GHz Band Cassegrain Earth Station Antenna for the Japanese Domestic Satellite Communication System

An 11.5 m 30/20 GHz band Cassegrain antenna has been developed for a Japanese domestic satellite communication system earth station. In order to form an economical satellite communication network, the earth station antenna is required to be installed on the top of a telephone office building in a large city. Therefore, interference with terrestrial radio relay systems and antenna load on a building become the most important problems to be investigated. Considering the satellite position in geostationary orbit, a limited steerable system combined with a two-jackscrew drive mechanism is employed to lighten and simplify the antenna structure. Measured antenna aperture efficiencies are 72% in 20 GHz band and 68% in 30 GHz band. Measured wide angle radiation patterns satisfy the CCIR recommendation level. TheG/Tof the antenna at the feed horn port is measured to be 53.9 dB/K atEl = 45degat 18.75 GHz. Interference with the 20 GHz band terrestrial radio relay system in extremely near field was experimentally studied. Results show that the terrestrial system's antennas can be installed closely up to about 20 m without serious interference.     

Design and Analysis of High Gain Linear Rectangular Microstrip Array Antenna at 20.2 GHz of Ka Band

Wireless Personal Communications - Day by day user demand for high data transmission with uninterrupted service leads to usage of high frequency. To fulfill the demands ISRO launched GSAT-14 with...     

智能天线跟踪波束与切换波束的比较

首先从波束形成或控制的角度界定了2类智能天线—跟踪波束智能天线(以下简称跟踪波束系统)和切换波束智能天线(以下简称切换波束系统)。其次分别介绍了其中关键部分:跟踪波束系统的自适应方法和切换波束系统的波束选择方法的设计考虑。跟踪波束系统的自适应方法是利用基于Lagrange公式的自适应算法跟踪最强信号源,而切换波束系统的波束选择方法则是基于正确波束接收的信号必然比任何其他波束接收的信号强这个事实。最后,依据其性能和所需的复杂度对跟踪波束系统和切换波束系统作了比较。