馈电网络子结构三端口散射参数测量方法研究

从多模馈电网络子结构的特性出发,对可能获取子结构三端口散射参数的方法进行了分析、比较,在现有二端口矢量网络分析仪的基础上,考虑了端口的阻抗匹配,对馈电网络子结构的三端口散射参数测量进行了实验研究,并应用混合模式散射参数验证了测量方法的准确性,为整个多模馈电网络的设计和优化提供有力的支持。     

计算机辅助的插值算法在微波器件设计中的应用

均衡器、多模多馈天线是具有复杂结构的微波器件,由于其测量数据库总是由离散的有限点集组成,因而对其子结构测量数据库采用插值法进行无缝化处理就成为这些微波器件优化设计的关键技术之一.针对这些微波器件的测量数据库,提出了一种工程上实用的多维插值算法,并介绍了该算法的主要思想.利用C Builder编程软件和MATLAB拟合软件,给出了均衡器、多模多馈天线的插值实例,并利用Origin图形软件对其插值特性进行了分析和改进.计算和分析结果表明,该算法能在较高的插值精度条件下对数据进行有效的插值处理.且该算法在微波器件的工程设计中具有一定的推广应用价值.     

传输线变压器分析方法的matlab仿真

传输线变压器是多模多馈天线系统中的重要部件，由它构成的阻抗变换器和功率合成与分配器件组成的多模馈电网络是实现多模多馈特性的关键。由于它具有频带宽。阻抗匹配好，截止频率高，功率容量大等特点，现在已经广泛用于通信的各个领域。对于传输线变压器性能的分析有多种不同的分析方法，但都有着各自的优缺点。该文分别应用考虑线圈互耦的等效电路模型和不对称传输线思想分析了传输线变压器的特性，并将频率变化对磁导率的影响应用到等效电路模型特性中，最后以输入阻抗为例结合实际测量用matlab对两者的分析结果进行了仿真比较，给出了比较性的结论。     

多模基片集成波导波束成形网络的散射矩阵分析及应用

通过对多模波束成形网络散射矩阵的分析,我们在介质基片Rogers5880上设计并加工了基于多模基片集成波导的波束成形网络。这一新型的结构不仅具有传统波束成形网络(如Butler矩阵)的优良性能,而且具有诸如小型化和辐射功率高等一系列优点。将这一结构与基片集成波导缝隙阵天线相级联,可集成为平面多波束天线阵。测试结果表明这种多模波束成形网络适用于微波毫米波多波束智能天线系统,且与仿真分析相比具有较好的一致性。     

一种分形结构微带天线的设计和馈点的优化

微带贴片天线是一种低材料、体积小、易于制作的天线。为了实现天线的多频带特性,在微带贴片天线中引入了sierpinski模型结构。分形结构是在一个递归的过程中产生的,它们可以在有限的空间产生很长或很宽的表面积,因此,分形结构可以使宽带天线在小型化的同时又能保持和大天线相似的辐射模式和输入阻抗特性。这种sierpinski分形结构的微带天线可以用在WLAN,BLUETOOTH和WIMAX中。本文详细研究了sierpinski分形结构的迭代设计以及馈带线的馈点位置,并分析了对于此类天线的最佳馈电点     

双频共面电容耦合对称低轮廓微带天线的研究

本文提出了一款双频共面电容耦合对称低轮廓微带天线。该天线将同轴探针馈电方式与耦合馈电方式进行了有效的结合,融合共面、地轮廓等要素,制作出一款适用于WLAN系统的微带天线。本文在设计优化天线结构的基础上,制作了一款共面电容耦合对称低轮廓微带天线,并经过网络分析仪等测试仪器进行测试,结果表明:该天线适用于WLAN双频系统中。     

双频共面电容耦合对称低轮廓微带天线的研究

本文提出了一款双频共面电容耦合对称低轮廓微带天线。该天线将同轴探针馈电方式与耦合馈电方式进行了有效的结合,融合共面、地轮廓等要素,制作出一款适用于WLAN系统的微带天线。本文在设计优化天线结构的基础上,制作了一款共面电容耦合对称低轮廓微带天线,并经过网络分析仪等测试仪器进行测试,结果表明:该天线适用于WLAN双频系统中。     

星载L波段宽带高增益圆极化微带天线设计

针对卫星L波段通信转发系统的要求,设计了一种新型星载L波段宽带高增益圆极化微带天线.微带天线整体采用侧馈的馈电方式,采用H型缝隙耦合馈电方式以实现宽频带,采用威尔金森移相功分器实现两信号间相位差来满足圆极化,增加天线背部反射板和板间泡沫层以提高增益并稳固结构.通过电磁仿真软件分析可得:在中心频点1.45 GHz处增益为...     

星载合成孔径雷达双极化天线阵研究

介绍了一种宽带双极化星载SAR有源相控阵天线阵,该天线以TR组件和双极化线阵组成的有源线阵为基础,并根据相控阵天线对雷达信号瞬时带宽的限制条件,选择合适的实时延迟子阵,结合结构安装的要求,构成电气独立的模块。在此基础上,根据雷达对天线孔径大小的需要,通过馈电网络激励拓展成大型有源相控阵天线,该天线可以通过波控灵活的控制和网络的合成,实现多极化、波束扫描、波束赋形和多通道等功能。其中对于双极化辐射天线,分别针对微带贴片天线阵和波导缝隙天线进行了分析和研究,并给出了实验验证结果。微带天线阵采用宽带的双层贴片辐射单元和并馈网络实现大带宽要求,两种正交极化模式分别由共面微带线和缝隙耦合来激励,其馈电网络居于开有耦合缝隙接地板的两侧,实现复杂网络空间安排和降低馈线耦合的功能。对于贴片单元的激励,采用对称、反相馈电和分组优化等方法,有效地提高了极化隔离度和极化纯度;而双极化波导缝隙阵中,以脊波导宽边纵缝谐振阵实现垂直极化,波导窄边非倾斜缝隙阵实现水平极化,在每种线阵中都通过分组馈电、过载技术和辐射/馈电波导一体化设计,实现了宽带和压缩横截面的目的。两种形式的天线阵比较,阵面剖面高度相当,微带阵具有宽带、轻质、易于加工和成本低等优势,而波导缝隙阵则具有高效、高隔离度和低交叉极化等性能,但是其缺点是结构复杂、加工难度大和重量大等。     

用于WLAN的高隔离度双频MIMO天线

为满足无线局域网(WLAN)性能需要,设计了一种利用Y型地板枝节和L型地板缝隙结构来提高天线隔离度的双频多输入多输出(MIMO)天线.天线基本结构为印刷单极子天线,馈电方式为微带线馈电.通过在L型单极子天线结构上加载一条L型辐射枝节,实现天线的双频特性,天线单元间结构相同且对称.仿真结果表明:天线在S11≤-10 dB...     

A compact substrate‐integrated‐waveguide monopulse slot antenna array with TE20 mode

A compact substrate‐integrated‐waveguide (SIW) monopulse slot antenna array with T_E20 mode is proposed, manufactured, and tested in this communication. The TE₂₀ mode electric field distribution is used in this antenna design. The phase difference required by the monopulse system is constructed by changing the orientation of the end of the top microstrip feed line. The microstrip line implements not only the feed function, but also the function of a monopulse comparator. The design greatly reduces the size of the monopulse comparator and the feed network, and improves the aperture efficiency of the antenna. Our measurement shows that the operating frequency of the antenna is 10.4 GHz, and the maximum gain of the sum beam is 13.7 dBi, and the difference beam null depth is ?26 dB. The antenna has the advantages of simple structure, small size, and easy integration of planar circuits. This proposed idea can open new ways for monopulse antenna design.     

A cubic dual band near-field focused array antenna using composite right/left handed transmission lines

This paper proposes a new method for design of a dual-frequency near field-focused (NFF) antenna. A 4 × 4 array of dual-band patches and a dual-band feed network are designed to provide a phase distribution at 2.4 and 5.8 GHz. Rectangular patches with U-shaped slot be used as the double-band patches. The composite right/left handed transmission lines (CRLH TL) are used in design of a dual-band phase distribution network for the patches. Finally, a three-dimensional cubic structure is proposed to isolate the feed network and thereby improve the antenna performance. A prototype of a cubic dual band 4 × 4 near field focused array antenna is fabricated and tested. The measurement results have good agreement with simulation results.     

A low‐profile,low‐cost antenna system with improved gain for DSRC vehicle‐to‐vehicle communications

A novel wire antenna for future dedicated short range communications vehicle‐to‐vehicle communications is introduced. The proposed antenna carries low‐profile and low‐cost features, and possesses an improved gain performance. This article also includes a specific feed network design for the proposed antenna to meet the mechanical and manufacturing requirements. Two different numerical techniques using CST Microwave Studio and HFSS have been applied for evaluating the performance of the proposed antenna. The whole system including the feed network and the antenna elements is integrated, and its performance is also assessed. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

A dual‐polarized low‐profile microstrip patch antenna with U‐ or M‐shaped feed network

In this article, a dual‐polarized low‐profile microstrip patch antenna with U‐ or M‐shaped feed network is presented. The U‐ or M‐shaped feed network is printed on the same layer, which can achieve dual bands (5.3 and 5.8 GHz) and low profile (0.06 λ_g). Dual polarizations and high isolation are realized by making use of a quasi‐cross‐shaped slot feeding. Moreover, the port isolation is better than 25 dB, and the antenna gain is above 8.4 dBi for the two ports. And the cross‐polarization levels in both E and H planes are better than ‐30 dB for the two polarization ports, respectively. The design is suitable for array application in MIMO system. Details of the proposed design and experimental results are presented and well agreed.     

A high‐gain dual‐band directional/omnidirectional reconfigurable antenna for WLAN systems

A high‐gain dual‐band antenna for the wireless local area network system is presented in this article. Two symmetrical linear arrays can be dynamically reconfigured that could switch radiation pattern with a switchable feed circuit between direction and omnidirection. The antenna can also be used for a pattern diversity antenna for the multiple‐input–multiple‐output communication systems. The design process for the antenna system is given, and the parameters and characteristics of the antennas are achieved by the method. Measured return losses, isolation, and radiation patterns are in good agreement with the simulated ones, which illustrates that the method is valid and the antenna system can be integrated with pattern reconfigurable and pattern diversity applications. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Adaptive acquisition and tracking for deep space array feed antennas

The use of radial basis function (RBF) networks and least squares algorithms for acquisition and fine tracking of NASA's 70-m-deep space network antennas is described and evaluated. We demonstrate that such a network, trained using the computationally efficient orthogonal least squares algorithm and working in conjunction with an array feed compensation system, can point a 70-m-deep space antenna with root mean square (rms) errors of 0.1-0.5 millidegrees (mdeg) under a wide range of signal-to-noise ratios and antenna elevations. This pointing accuracy is significantly better than the 0.8 mdeg benchmark for communications at Ka-band frequencies (32 GHz). Continuous adaptation strategies for the RBF network were also implemented to compensate for antenna aging, thermal gradients, and other factors leading to time-varying changes in the antenna structure, resulting in dramatic improvements in system performance. The systems described here are currently in testing phases at NASA's Goldstone Deep Space Network (DSN) and were evaluated using Ka-band telemetry from the Cassini spacecraft.     

A wideband circularly polarized antenna array with sequential rotation feed

A novel wideband circularly polarized (CP) antenna array is designed, which consists of a horizontally placed wideband phase shifting feed network and four vertically placed linearly polarized dipole antenna elements, and the circular polarization is realized based on sequential rotation feeding technology. By placing two parasitic strips and two grounding strips on the top and side of each T‐shaped dipole antenna element, the impedance bandwidth and circular polarization performance of the antenna can be further improved. The simulation results show that the 10‐dB impedance bandwidth of the antenna is 93% (1.56‐4.27 GHz) and the 3‐dB AR bandwidth is 80.7% (1.7‐4.0 GHz). The measured results are in good agreement with the simulation results. Due to the use of orthogonally placed wideband feed network and wideband array elements, the proposed antenna array has a wider circular polarization bandwidth than the similar antenna arrays reported.     

High frequency integrated feed for front end circuitry and antenna arrays

Low‐cost printed circuit board waveguide (PCBWG) technology is employed to develop new waveguide‐fed microstrip antenna arrays with low profile and light weight while maintaining high efficiency and gain at 12.5 GHz. The proposed corporate feed network has two parts: on the antenna layer, microstrip lines are used to form a 2 × 4 sequentially rotated sub‐array of circularly polarized microstrip patches and on the feed layer PCB‐WG is utilized to combine any number of these sub‐arrays to form a larger array. Because PCB‐WGs transmit the power over a large portion of the feed network, losses are substantially reduced and spurious radiations from feed circuit are eliminated. Several microstrip arrays with PCBWG feed were designed and fabricated using standard PCB process. Comparing the results with those of a hybrid array with conventional waveguide feed shows that there is only a negligible degradation in gain and efficiency when bulky and expensive aluminum waveguides are replaced by PCB‐WGs. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A dual feed PIN diode based switchable multiband planar meandered antenna for intelligent transportation system application

This article presents a dual feed switchable coplanar linearly polarized multiband meandered microstrip patch antenna. The antenna provides multiband functionalities with switching allowable at one of the nine adjacent frequencies. The proposed antenna, loaded with two symmetric PIN diodes, comprises dual‐patch configuration and excited by coplanar microstrip feeds, it operates within 1 to 15 GHz frequency bands. The induced current of the antenna can be changed by switching the diodes, resulting in different operating frequency bands. The antenna has a nearly broadside radiation pattern and the impedance bandwidth is obtained up to 47% having a center frequency of 2.4 GHz for band range of 1 to 15 GHz. The measured gain of the antenna for 1.57, 2.4, 4.5, 4.71, 5.9, 6.53, 7.59, 10.8, and 11.87 GHz are 5, 5, 7, 6, 6.1, 4.4, 3.8, 3.5, and 1.87 dBi, respectively. The antenna has advantages of the simple biasing network, easy fabrication, and adjustment. It is suitable for many modern wireless communication systems like intelligent transportation system. This antenna is also useful in direct broadcast satellite applications.     

Reconfigurable wide band circularly polarized antenna array for WiMAX,C‐Band,a and ITU‐R applications with enhanced sequentially rotated feed network

In this article, a wide‐band circularly polarized slot antenna array with reconfigurable feed‐network for WiMAX, C‐Band, and ITU‐R applications is proposed. Different novel methods are used in proposed array to improve antenna features such as impedance matching, 3 dB axial‐ratio bandwidth (ARBW), gain, and destructive coupling effects. Miniaturized dual‐feed square slot antenna, with one attached L‐shaped strip and a pair of T‐shaped strip at ground surface for improving impedance matching and circular polarization (CP) purity, is presented. For further enhancement of CP attributes, reconfigurable sequentially rotated feed network is utilized to obtain wider 3 dB ARBW. Furthermore reconfigurable property of network gives controlling Right and Left handed CPs, respectively. Finally, a special form of Electromagnetic Band gap structure is employed on top layer of substrate that provides high isolation between radiating elements and array feed network to enhance overall performance of antenna. The measured results depict 3 dB ARBW from 4.6 to 7.2 GHz, impedance bandwidth from 3.3 to 8.8 GHz for VWSR<2, and peak gain of 10 dBi at 6 GHz. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:825–833, 2015.