3300mm口径W波段辐射计偏馈反射面天线设计

本文为W波段辐射计设计了一副口径为300mm偏馈反射面天线,天线要求的工作频率为94.5GHz,副瓣电平低于-25dB,交叉极化电平低于-30dB,半功率波束宽度优于1?。文中采用较小偏置角以改善偏置天线的交叉极化特性,采用焦面场匹配法和模比利用法设计了匹配馈源,通过仿真优化设计,得到良好的波瓣等化电平和驻波比。测量结果表明,测量值与理论值吻合,满足辐射计的指标要求。     

Compact antenna test range reflector edge treatment

The physical optics technique is used to compare the performance of single offset compact antenna test ranges with different reflector edge treatments and rim shapes. A comparison between reflector edge taper and rim serrations in controlling edge diffraction is demonstrated     

Compact range reflector edge treatment impact on antenna andscattering measurements

Compact range measurements with a serrated edge and a blended, rolled edge reflector are compared. This is done by using simulated antenna pattern and backscattered field measurements. The measurement errors caused by stray signals emanating from the edge termination of reflector are discussed. It has been found that different stray signal sources impact on the measurement accuracy from different aspect angles. In addition, the measurement accuracy achievable with different reflector systems is dependent on the characteristics of the antenna or scatterer under test. From these findings, one will be better able to understand how well these two types of reflectors will perform in terms of accurately providing the proposed measurements. Consequently, one will be able to choose the best reflector design for his/her application     

Compact antenna test range without reflector edge treatment and RF anechoic chamber

There are several types of CATRs (compact antenna test ranges) used in antenna-pattern measurements. An offset reflector is generally used to generate the quiet zone of a CATR. Serrated edges, rolled edges, or R-cards are generally chosen along the reflector's edge to reduce the edge-diffraction field inside the quiet zone of the CATR. In order to reduce stray signals from the environment, a high-quality RF anechoic chamber is required for a CATR. In this paper, a new type of CATR, without either a reflector edge treatment or an RF anechoic chamber, is developed. A commercially available DBS (direct-broadcast satellite) reflector antenna, without edge treatment, is used as the reflector antenna of the CATR to generate the quiet zone of the antenna test range. In order to improve the quiet zone's performance, the fields due to feed spillover, edge diffractions, and other stray signals are gated out by the ITDAMS (impulse time-domain antenna measurement system). The RF interference in the environment can also be reduced by time synchronization and pulse integration of the impulse time-domain antenna measurement system. In order to verify the capabilities of the proposed CATR, three kinds of antennas (a low-directivity horn antenna, a high-directivity 60 cm direct-broadcast satellite reflector antenna, and a 25 cm Ka-band Cassegrain LMDS - local microwave distribution system - antenna) were measured by the proposed CATR. The antenna-pattern results agreed quite well with those of a near-field range and a far-field range.     

W-band substrate integrated waveguide slot antenna

A W-band substrate integrated waveguide slot antenna has been designed and tested. The antenna has been realised using a reduced height waveguide in photoimageable thick film technology. Experimental and simulated return loss and radiation pattern measurements are presented.     

Bicollimated Gregorian reflector antenna

A bicollimated Gregorian reflector is structurally similar to a classical confocal Gregorian reflector, but its surfaces are shaped to have better scan capability. A geometrical optics procedure is used in designing the reflector surfaces. A three-dimensional ray tracing procedure is used in analyzing the aperture phase errors as the beam is scanned to different angles. The results show that the bicollimated configuration has about 45 percent greater angular scanning range than the equivalent confocal Gregorian reflector antenna.     

Bifocal dual reflector antenna

A bifocal dual reflector antenna is similar to and has better scan capability than a classical Cassegrain reflector antenna. The method used in determining the reflector surfaces is a modification of a design method for the dielectric bifocal lens. Computed radiation characteristics of the bifocal reflector system are compared with those of a classical Cassegrain reflector system. The results confirm that the bifocal reflector has superior scanning performance.     

Microwave technique for reflector antenna profile measurement

A method for microwave measurement of the reflector antenna surface profile is described. The technique uses a focused monostatic secondary reflector located on axis at approximately two focal lenths from the reflector under test. Measurement of the two-ways phase change provides profile error information over a set of annular sections. Practical results are provided to illustrate the spatial resolution and sensitivity of the technique.     

Contoured beam reflector antenna for wireless applications

Wireless coverage in urban, suburban, and light industrial areas is a challenging problem for cellular network planners. This is mainly due to scattering from buildings and structures but also because area specific demographic features such as parks, streets, and sports arenas require specialized coverage. A contoured beam reflector antenna is a simple and effective solution for this problem, providing excellent control in both planes of the radiation pattern and a very sharp taper at the edge of coverage. The problem of wireless coverage planning using existing base-station antenna types is discussed, and a potential solution for these problems using contoured beam reflector antennas is demonstrated by examples. The implementation of this solution is made possible by using an inexpensive manufacturing technique involving a reconfigurable mould and a foam extrusion process     

Flat printed reflector antenna for mm-wave applications

An antenna consisting of a flat printed reflector and a feed horn was investigated at mm-wave frequencies. The dielectric material is fully metal covered at the side opposite to the feed, whereas the side facing the feed is provided with a number of metallic annular rings forming a Fresnel zone plate     

Analysis of reflector antenna systems with arbitrary feed arraysusing primary field superposition

In contrast to secondary pattern superposition, where the fields reflected from the main reflector arising from each element are superimposed in the far field of the reflector, the approach presented here sums the primary fields at the reflector surface before the physical optics radiation integral is performed. The method allows each feed array element to have arbitrary position, orientation, pattern, and excitation (magnitude and phase). In addition, it is inherently efficient because evaluation of only one time-consuming radiation integral is required, rather than one per feed element as in secondary superposition. The method allows for accurate calculation of the power radiated from the feed, permitting the reflector gain and spillover efficiency to be determined within the context of a single computer program. The accuracies and characteristics of this method are demonstrated with several examples     

太赫兹赋形面天线技术

概述太赫兹技术及太赫兹天线的发展状况,重点介绍太赫兹赋形面天线技术在太赫兹准光系统、太赫兹通信系统、太赫兹成像系统等领域的应用。赋形面技术主要基于能量守恒定律和等光程原理将出射的波束转换成要求的场分布。赋形反射面能够实现标准反射面不能实现的功能。因此赋形面技术将大大拓展现有的反射面天线在太赫兹波段的应用场景,并能提高太赫兹系统的幅度和相位特性。     

A novel frequency-scanned reflector antenna

Theoretical and experimental results are presented for a frequency-scanned antenna composed of a line source and a frequency-scanned reflection grating that is shaped to a cylindrical reflector. The principle considering is to select the grating geometry such that the first higher-order diffracted wave propagates and serves as the frequency-scanned beam. An analytical solution for the cylindrical reflector geometry that gives a line focus is given. The grating structure considered consists of an array of dipoles placed over a ground plane. The design of the dipole grating for optimum blazing (i.e., for optimal power conversion from the incident wave to the diffracted wave) is discussed. For the theoretical analysis Floquet's theorem and the method of moments are used     

Variable beamwidth corner reflector antenna

A simple and successful design for a variable beamwidth corner reflector antenna is presented. The gain and the -3 dB beamwidth of the antenna are predicted using the finite difference time domain (FDTD) method. The predicted results are compared with measured data and good agreement is reported     

Microwave holographic technique for reflector antenna profile measurement

A short-range microwave holographic technique for the measurement of reflector antenna surface profile is described. The technique uses a linearly scanned transmit/receive CW probe located on-axis at approximately two focal lengths from the reflector vertex. Rotation of the reflector provides a plane-polar data set which can be reconstructed by a fast algorithm to provide a surface profile error map. No special precautions are required with regard to the reflectivity of the environment. Practical results are provided to illustrate the performance of the system.     

Realizable feed-element patterns for multibeam reflector antenna analysis

The radiation pattern of a feed element is approximately described by a simple function(cos theta)^{q}. For a given element spacing of the feed array, we give simple formulas for estimating the practical value ofqwhen the element is an open-ended rectangular waveguide, an open-ended circular waveguide, a pyramidal horn, or a cigar antenna.     

W-band high gain lens antenna for metrology and radar applications

A W-band high gain lens antenna has been realised and measured. A hyperbolic lens made in ECCOSTOCK 0005 is associated to an optimised modified circular horn related to a circular-to-rectangular waveguide transition in order to fit the WR-10 standard waveguide. The antenna provides more than 30 dBi gain between 75 and 110 GHz. It is competitive in several fields of applications: first, obstacle detection radar application (at 77 or 94 GHz), secondly metrology, for example, in order to measure radar cross-sections over the whole W-band with a single antenna.     

W波段双极化单脉冲天线设计

为了探测目标的极化特性,研制了工作在W波段的双极化单脉冲卡塞格伦天线.天线由主反射面、副反射面、馈源喇叭、正交模耦合器及和差器组成.天线主反射面口径为137 mm,馈源为五喇叭形式,正交模耦合器采用渐变波导匹配方案,和差器通过平面型定向耦合结构实现.通过将馈源喇叭、正交模耦合器及和差器集成设计,减小了连接损耗,压缩了天线纵向尺寸.测试结果表明,天线驻波带宽约3. 7 GHz,极化隔离度优于35 dB,和波束增益大于37. 9 dBi,副瓣电平优于-15 dB,差波束零深优于-25 dB.天线在W波段实现了较好地双极化单脉冲性能.     

Compact diversity antenna for wireless devices

A compact diversity antenna, consisting of two E-shaped microstrip patch antennas, is presented. It has a wide bandwidth, covering all frequency bands of 5-6 GHz WLAN systems operating under IEEE 802.11a and HiperLAN2 standards. Corrugations have been introduced to reduce the overall width of the diversity configuration to 54 mm - the width of a standard PCMCIA card. The isolation between the two inputs is greater than 20 dB and the signal correlation is less than 0.2 over all WLAN bands.     

Compact W-band E-plane Waveguide Filter with High Selectivity

Journal of Infrared, Millimeter, and Terahertz Waves - In this letter, an E-plane substrate is inserted into the W-band standard waveguide to construct a bandpass filter (BPF) with high...