Feed circuits of double-layered self-diplexing antenna for mobilesatellite communications

An analysis of feed circuits for a double-layered self-diplexing antenna for mobile satellite communications is presented. It is possible to reduce the weight of the diplexer for a self-diplexing antenna by getting large internal isolation between transmitting and receiving. The internal isolation is shown to be heavily dependent on the configuration and errors of the feed circuits of the antenna. The feed circuits of two- and four-point feeds for the antenna are discussed, using the cavity model of microstrip elements, and an error analysis of the feed circuit is carried out     

Dual frequency multilayered circular patch antenna withself-diplexing function

A novel type of dual frequency and double-layered patch antenna with self-diplexing function is presented. Experimental results of the proposed antenna which consists of a circular patch antenna and a ring patch antenna with partially shorting planes are shown to verify the practicality of the new antenna configuration     

Design of a self-diplexing antenna using SIW technique with high isolation

In this paper, a novel and small substrate integrated waveguide (SIW) based self-diplexing antenna is presented. The proposed antenna exploits two quarter-mode SIW cavity resonators for radiation, which are realized by splitting a half-mode SIW cavity with the help of one open-ended slot. Each quarter-mode cavity resonator is excited separately by microstrip feedlines. By properly adjusting the corresponding dimensions of the antenna, a very high isolation of better than −30 dB is obtained between the input ports that helps to realize a self-diplexing phenomenon. The antenna exhibits two resonant frequencies of 6.44 and 7.09 GHz, with the corresponding gain values of 3.2 and 4.8 dBi, respectively. Moreover, the antenna shows unidirectional and stable radiation patterns at both operating frequencies, while it maintains a planar and simple configuration, which can be rescaled for any other desired frequency.     

Circularly polarized self-diplexing array antenna with higher gainoperation

The relationship between the rotation angle of linear polarization for a sequentially rotated circular array antenna and the array antenna gain has been demonstrated earlier, and a multiring array antenna with medium gain has already been proposed by the authors. Using these results, a novel self-diplexing array antenna with high isolation level and higher gain operation consisting of the above-mentioned multiring array is proposed, and the measured results are presented to demonstrate the proposed method of improving gain for both transmit (1.63 GHz) and receive (1.53 GHz) bands in L-band mobile satellite communication     

Thin-film HTS planar antennas

The “H” microstrip antenna is suitable for use as an efficient small antenna when it is constructed out of superconducting thin-film materials. An aperture feed and matching network is described which provides a convenient enhancement of the capabilities of the “H” antenna. Methods of prediction of the center frequency are given. In addition, an analytical expression is developed for the far field radiation pattern of the “H” antenna and the efficiency and Q of superconducting and copper antennas are described using this expression. It is likely that superconducting antennas will only have significant application when they are used in arrays. Three arrays are described demonstrating multiband self-diplexing multifrequency-enhanced bandwidth and multifrequency beam forming     

反射面相控馈源阵的动态阻抗匹配

对于相控阵馈源,其前端低噪放的噪声系数直接影响系统整体性能,在技术途径上,减小系统前端噪声系数的关键之一就是改善阵元与有源前端的匹配,即阻抗匹配。对于单个天线,阻抗匹配就是使得天线的输入阻抗等于低噪放的最佳源阻抗。但是对于相控阵,阵列的动态阻抗依赖于波束形成系数并且随着波束指向的变化而变化,阻抗匹配是比较复杂的。针对反射面相控馈源阵系统,采用HFSS鄄MATLAB 联合仿真的方法,设计了馈源天线和低噪放,自动完成天线参数和低噪放最佳源阻抗的优化实现动态阻抗匹配和多波束平均最优阻抗匹配,最后系统仿真进行了验证。     

智能天线射频前端频率合成器的设计与实现

文章介绍了智能天线射频前端的工作原理,并对射频前端的第一本振使用直接数字频率合成器（DDS）结合锁相环（PLL）的设计方案进行了讨论,分析了频率合成器的相噪特点和对寄生杂散电平的抑制措施,对智能天线射频部分的性能提高有一定参考意义。     

A novel fully integrated transmitter front-end with high power-added efficiency

A novel fully integrated transmitter front-end with a simple structure is proposed to obtain both high power-added efficiency (PAE) and a compact RF-front structure. To have all these characteristics, a novel antenna operating as a radiator, a harmonic tuning circuit, and an output matching network of the power amplifier is proposed. Therefore, the direct integration of the output of the power amplifier and antenna can be achieved without any impedance transformers. From the measured results and fabrication, it is shown that the proposed transmitter front-end provides high PAE of 67.5% and compact and integrated RF-front structure by the size reduction of 43% compared with the conventional class-F active antenna for high PAE.     

毫米波雷达四元微带双天线阵的研制

本文介绍了一种应用于收发分离体制毫米波雷达前端的小型微带阵列双天线.双天线包含两个四元并馈微带天线阵,共置于直径为18.6毫米的圆形衬底上,分别作为雷达前端的接收和发射天线.前端电路采用自行研制的毫米波雷达MMIC套片,利用MCM技术集成在与天线共型的圆形衬底上,与天线以背对背方式连接,采用小孔耦合技术进行场耦合.经过对天线和整个前端的测试,收发天线提供了10.5dB的增益,两天线问的隔离度优于-34dB,雷达前端具备良好的收发性能.     

应用于交通信息检测雷达的阵列天线设计

介绍了一种应用于交通信息检测中多普勒雷达前端的K波段64阵元微带双天线,该天线采用并联形式馈电,通过对天线互耦的分析,电抗补偿和减小耦合等方面的改进,满足了天线性能和尺寸等实际应用的需求。双天线衬底背面固定集成雷达收发前端和中频信号处理电路。经过对天线和整个系统前端的测试表明:天线在工作频点,回波损耗低于-20dB,最大增益为25.2dB,E面、H面半功率波瓣宽度为8.1°和6.3°,其仿真和测试结果较好吻合。整个雷达前端在实际外场测试中检测准确灵敏,并在实际智能交通系统工程中得到了很好的应用。     

应用于毫米波无线接收系统的高集成化LTCC AIP设计

介绍了一种基于低温共烧陶瓷工艺的新型高度集成毫米波无源接收前端,该前端由阵列天线、馈电网络和带通滤波器构成.上述无源器件以天线集成封装方式经过一体化设计,并应用于毫米波无线系统.首先,设计了2×2线极化空气腔阵列天线,通过采用新颖的内埋空气腔体结构,使天线最大增益提高了2.9 dB.其次,将具有双层谐振结构的三阶小型化发卡型带通滤波器和天线馈电网络进行一体化设计.该滤波器测试结果显示:插入损耗为1.9dB,3 dB相对带宽为8.1％(中心频率为34 GHz).最后将上述天线和滤波网络进行一体化设计,实现了三维无线接收前端.在集成结构中,通过采用金属柱栅栏抑制了寄生模式.测试结果显示天线最大增益可达14.3dB,通过集成滤波馈电网络,其阻抗带宽为2.8 GHz.该新型一体化集成前端系统具有良好的射频性能,可作为全集成无源前端应用于Ka波段无线系统中.     

Broadband Active Receiving Patch With Resistive Equalization

The active integrated antenna (AIA) concept has been applied to design a broadband receiver front-end. A design procedure for active broadband patch antennas based on resistive equalization is presented. The use of the AIA has allowed the design of efficient RF front-ends by increasing its effective gain, noise figure, and merit . In addition to improving the classical parameters, the resistive equalization technique allows enlarging the bandwidths of the active antenna parameters versus the corresponding ones in passive antennas. A receiving patch antenna (with one amplifying stage) with a measured noise figure lower than 0.6 dB in a bandwidth over 38% and an effective gain improvement of 13 dB over the corresponding passive antenna has been achieved. The -parameter has also been measured for both the active and passive antenna, resulting in a relative planar of 16 dB/K, with a ripple of 0.5 dB, over a 30% bandwidth for the active antenna versus a of 22 dB/K for a typical front-end with a passive antenna over 20% bandwidth.     

A Unified Mutual Coupling Model for Multiple Antenna Systems

The use of multiple antennas can offer substantial performance improvement to a wireless communication system by spatial multiplexing methods or diversity methods[1]. In the multiple antenna receivers, each antenna requires another Radio-Frequency (RF) front-end chain. To achieve high multiple antenna gain, the multiple received signals arriving at the Combined Signal Processor (CSP) module should be independent and hold balanced mean power[2]. There are several factors affecting the corre…     

A Web-based distributed computing framework for antenna array modeling

The purpose of this article is to present a distributed computing framework that is used as a purely Web-based simulation environment for antenna array modeling. The framework adopts a three-tier architecture. The front-end part is mainly based on dynamic Web pages for the selection of antenna parameters, enhanced by the VRML standard for visualization of the geometry and results. The middle part of the architecture is based on Java servlets, which are responsible for handling the front-end communication with the remote user and setting up the simulation. Finally, the back end of the architecture is responsible to distribute the computations to a set of computing nodes. This part employs a purely Web-based mobile agent platform, responsible for the execution of partial simulation code to remote hosts. In the context of the article we demonstrate the applicability of the framework in antenna array modeling by presenting a specific parametric simulation of conformal antenna arrays.     

Conformal Antennas on Liquid Crystalline Polymer Based Rigid-Flex Substrates Integrated With the Front-End Module

Recent developments in liquid crystalline polymer (LCP)-based processing technology have shown that highly-integrated, fully-packaged radio-frequency (RF) front-end modules with high-performance can be designed by using the system-on-package (SOP) approach. However, the direct integration of a large antenna element to a small module package still remains an issue. This paper presents a novel conformal antenna structure, which results in a compact integration of the antenna and the module package for 5 GHz WLAN/WiMAX applications. The extension of 5 GHz single-band operation to 2.4/5 GHz dual-band operation is also discussed in this paper. The antenna is an inverse L-shaped monopole printed on a 25-$mu{hbox {m}}$-thick flexible LCP layer, which protrudes from a rigid multilayer organic substrate. The shielding effects of a grounded metal case, which can house the associated module circuitry, are also considered during the design process. The metal case serves as a vertical ground plane for the antenna in addition to protecting the module circuitry from the near-fields of the antenna. The flexible LCP substrate can be bent and folded over the module case, resulting in a compact design and the tight integration of the antenna with the front-end module. The details of the design and the fabrication of the proposed structure as well as the simulation and the measurement data are presented in this paper.      

Active 60 GHz front-end with integrated dielectric antenna

The hybrid integration of a dielectric antenna together with an MMIC low-noise amplifier in a 60 GHz front-end is presented. It is demonstrated how a low-loss substrate integrated dielectric antenna can efficiently be interconnected at miniature scale with the coplanar waveguide input of the MMIC. The experimentally obtained return loss is better than 11 dB from 55 to 65 GHz. Transmission path loss measurements of a wireless link confirm the low-loss potential of this approach for millimetre-wave front-ends.     

RF Front-End Passive Circuit Implementation Including Antenna for ZigBee Applications

This paper presents a front-end passive circuit module for ZigBee applications using low-temperature co-fired ceramic technology. The front-end part consists of an antenna, a bandpass filter, a switch, and two baluns. In antenna design, the solenoid shape is employed for reducing the size of the antenna, resulting in an overall size of 9times16.4times1.82 mm³ and a gain of -1.4 dBi. As for the filter, two types of filters are suggested. First, the lumped-type filter employing a high-Q spiral inductor has more than 20-dB attenuation at both stopbands, very near to the passband. Secondly, the semilumped-type filter adopting an edge coupled line and a loading capacitor provides a group delay of below 5 ns and is adequate for the full module structure due to the structure flexibility. A balun is evaluated using lumped components instead of a transmission line and, thus, it provides an insertion loss of only 0.3 dB and a phase difference of 180deg between balanced signals. Based on these components, an RF front-end module including attaching pads for an RF integrated circuit (IC) and baseband IC is implemented. In case of using the lumped-type filter, the insertion loss of the front-end module is 6.5 dB, and the group delay is below 7 ns. In case of adopting the semilumped-type filter, the insertion loss is 6.2 dB, and the group delay is below 4 ns. The overall size of the former and latter is 25.14times28.5times0.68 mm³ and 25.66times25.58times1.17 mm³, respectively     

An LTCC-Based Wireless Transceiver for Radio-Over-Fiber Applications

This paper describes the realization of a low-temperature co-fired ceramic (LTCC)-based wireless transceiver with optical interface for radio-over-fiber applications involving several standards. The RF front-end including an antenna is fabricated in LTCC technology, while the optical transceiver with a single-mode optical interface is built on a silicon motherboard. The front-end operates in the 5-6-GHz band, while the modulated optical carrier is transmitted at 1.55-mum wavelength. The front-end module is an attractive solution for wireless local area network applications such as IEEE 802.11a or HIPERLAN2 requiring a direct link to an optical backbone     

Active Integrated Antenna Design Using a Contact-Less, Proximity Coupled, Differentially Fed Technique

A novel contact-less, differential feeding technique suitable for integrated active antenna design is demonstrated. This technique utilizes an odd mode signal to generate fringing fields on either side of a microstrip gap under the antenna. This allows electromagnetic energy to be efficiently coupled from the transmission lines to the radiating antenna. In a balanced integrated antenna amplifier configuration, the proposed non-contact feeding method removes the need for any balun or power combining network. Hence in theory, a compact RF front-end design with lower losses can be realized. This feeding method has been successfully applied to the design of simple passive microstrip patch antennas and active integrated antennas (AIA). Simulated and measured results are also included to validate the proposed feeding concept and antenna designs. The performance of the proposed differential feeding technique on a simple microstrip patch antenna has been systematically studied. The study suggests that the proposed proximity method is broadband in nature, allowing antennas operating at different resonant frequencies to be swapped without the need to change the feed dimensions and without degrading the matching performance     

伪随机码调制连续波雷达泄漏信号抑制途径

介绍了连续波雷达针对泄漏信号的设计考虑和几种比较实用的泄露信号抑制方法。泄漏问题是连续波雷达设计必须考虑和解决的,接收前端增益应根据泄露信号电平来设计,天线的隔离度应保证接收机工作与线性状态。几种泄露抑制方法大多做过专题试验,可供参考。