Quantization Error Reduction for the Phased Array with 2-bit Phase Shifter

It has been widely believed that phased array antenna should use at least 3-bit (as phase controlling bit) phase shifter to provide the satisfactory scanning capability and the unnoticeable parasitic sidelobes. In this paper, we proposed a novel phase perturbation method, namely, virtual feed approach, derived from the general concept of the phase randomization, to improve the performance for the low-cost electronic scanning antennas with 2-bit phase shifters. By using this method, problems of scanning error at small scanning angle as well as the relatively high parasitic sidelobes at large scanning angle are solved simultaneously at acceptable performance degradation.     

有限扫描反射面天线相控波束重构技术

该文研究一种采用聚焦馈源阵列馈电的反射面天线,相控阵馈源离开焦平面向反射面移动一定距离,位于焦散区,能够增强反射面天线的波束重构赋形能力和有限视角扫描能力。采用改进的投影矩阵法,利用仅相位控制技术,求解相控阵馈源的激励系数,有效综合了聚焦馈源偏置抛物面天线的方向图。对算例的设计达到了采用仅相位技术控制波束指向、波束赋形、旁瓣电平等性能要求,实现了相控阵馈电偏置抛物面天线的波束重构或扫描,并利用商用GRASP仿真软件验证了该文的设计结果,说明了该文方法的有效性。     

A scanning reflector using an off-axis space-fed phased-array feed

An architecture for a scanning reflector antenna that supports wide-angle scanning, multioctave tunable bandwidths, transmit and receive operation, and monopulse processing is presented. It consists of a parabolic dish with an offset phased array. The array is actually a feed-through lens fed from a small feed array in the back of the lens. Beam steering is accomplished by using the feed array to illuminate clusters of elements within the lens that correspond to far-field beam positions. The evolution of the architecture and a computer model is described. Simulated and measured performance results are reported. Off-axis scanning of 10° to 15° appears to be possible while still supporting gain magnifications of four to five     

反射面天线焦面场采样研究与相控阵馈源设计

为了设计高性能的相控阵馈源(phased array feed,PAF),通过反射面天线焦面场最优采样的研究,给出了PAF参数与天线口径效率之间的关系,总结了PAF的最优采样范围和单元间距,导出了PAF单元数量的计算公式.给出了一个9 m天线的PAF设计实例和性能分析,在4～7 GHz频率范围内,扫描范围为±3°时,天...     

Phased array for millimeter wave frequencies

A phased array is presented at a frequency of 70 GHz, consisting of a corporate feed, ferrite phase shifters and dielectric rod antennas. Metal waveguides were utilized to construct the feed network, whereas a special dielectric waveguide structure was employed for the ferrite phase shifter and dielectric rod antenna. Beam scanning can be performed electronically controlled in the horizontal plane.     

A high aperture efficiency, wide-angle scanning offset reflectorantenna

A unique single offset reflector antenna has been designed which provides as much as ±30° of scanning in azimuth while maintaining a much higher aperture efficiency than a torus antenna. Like a torus antenna, different portions of the reflector are illuminated for each scanned beam. The reflector profile curve in the plane of scan is found by least squares to minimize the error for the beams with the greatest scan angle, and then polynomial terms of up to sixth order which minimize nonplanar phase errors are added to produce a three-dimensional reflector surface. Numerical simulation indicates very good results for all 0.5° beams in the ±30° azimuth field of view, with peak gain no more than 0.3 dB below ideal and highest side-lobe levels no worse than 13.3 dB below the peak gain. Additionally, comparable performance can be extended to the elevation plane out to 15°/-30°, although full azimuth performance becomes compromised at extreme elevation scan angles. By using an offset design, there is no blockage of the outgoing beam by the feed array assembly for azimuth scanning. With better feed performance than comparably sized paraboloids, and being more compact than similar torus reflectors, this novel antenna should find numerous uses in spacecraft and terrestrial applications     

一种基于压控移相技术的低成本相扫天线

研制了一种基于铁电体压控移相技术的低成本相扫天线阵列,该天线采用空间馈电透镜型式,省去复杂的馈电网络,减少移相器/TR组件数量,能显著降低相控阵天线的制造成本。介绍了空馈铁电体透镜相控阵天线系统的组成及其特点。对透镜天线关键部件的设计作了详细阐述,给出了12列铁电体空馈透镜天线阵列的实验结果,结果表明:在X波段,研制的铁电体透镜天线阵列在10%频带内可实现天线波束±45°的电控扫描,各扫描状态的输入驻波比小于1.4。     

A flat four-beam compact phased array antenna

This paper presents a flat four-beam compact phased array antenna. The low-cost and compact phased array antenna is designed using a circular array of four circular microstrip antennas made of low-cost material and four 1-bit phase shifters. The main beam of the antenna can be switched in four directions with the gain of about 4 dBi in each main-beam direction. More than 90° half-power beamwidth and over 10 dB F/B ratio are obtained. In addition, the diversity performance is considered and the diversity performance of this antenna can be provided with the envelope correlation about 0.6     

低成本风廓线雷达相控阵天线设计

本文针对风廓线雷达相控阵天线波束扫描特点,提出一种利用周期同相馈电法与驻波子阵形式相结合的设计方案。天线系统只需要五个移相器就可以实现相应的五波束扫描,简化了波束控制系统,降低了天线系统的复杂度与成本。     

Visualization of radiation-pattern characteristics of phased arrays using digital phase shifters

This article presents graphical investigations of the array factor of phased arrays with digital phase shifters. A software program, based on basic antenna array theory, has been developed in MATLAB to obtain the main array characteristics (array factor and directivity). The array factors of linear arrays of different sizes with different types of phase shifters have been studied as a function of the number of bits and the frequency. Unconventional two-dimensional color graphical representations are used to identify some characteristics of the array factor of arrays with digital phase shifters that can not be so clearly and quickly visualized with conventional graphical representations. In particular, the effects of quantization on the array factor for arrays of different sizes and for phase shifters with different numbers of bits, over scanning, and frequency ranges, are shown using this representation. Numerous data are also provided.     

基于DDS的有源相控阵天线

有源相控阵天线不仅能提高通信系统的性能,而且还能扩充其功能,所以在通信领域的应用越来越广泛.本文介绍一种没有高频移相器的8单元有源相控阵天线系统,它由平面天线阵、数字T/R组件、接收DBF和系统控制分析软件等组成.其基本原理是在发射模式下,利用直接数字合成(DDS)代替传统的高频移相器和衰减器.由于DDS的工作频率比较低,需要通过上变频到系统所需要的工作频率(2.0GHz).在发射模式下,通过控制DDS完成发射波束形成所必需的幅度、相位加权和上变频所必需的本振信号;在接收模式下,则利用DDS技术产生接收信号下变频所必需的本振信号,然后采用DBF技术形成接收波束.文中详细介绍了基于DDS的有源相控阵天线的实现方法和实验结果.通过8单元基于DDS的有源相控阵天线系统的研究,证实了DDS技术在相控阵天线中应用的显著优点和相控阵天线在通信领域具有潜在应用市场.     

An array-compensated spherical reflector antenna for a very large number of scanned beams

There are many stringent demands imposed on the applications of spaceborne antenna systems. One of the most challenging demands is the generation of multiple beams with the ability to scan a very large number of beamwidths. Since the parabolic reflectors have limitations in this application, a 35-m spherical reflector antenna is proposed for a geostationary radar antenna at Ka-band (35.6 GHz) due to its inherent capability of scanning the beams to very large number of beamwidths. The utility of using planar array feeds for correcting spherical phase aberrations is investigated to overcome the performance degradation effects. Two different methodologies are developed for the array excitation coefficients determination based on phase conjugate matching and the results are compared. Using the compensating feed array, the radiation characteristics of the compensated spherical reflector are simulated for no scan and large scan cases and the results are compared with the uncompensated case to show performance improvement. In order to demonstrate the technological readiness of the concept a 1.5-m breadboard model is designed to be built for experimental measurements. Some important mechanical design tolerances and realistic array feed topologies are investigated. The antenna concept developed in this paper is advocated to be used in the next generation of geostationary satellite antenna systems for remote sensing radar applications.     

Concept of an interlaced phased array for beam switching

A novel concept is described for feeding and phasing a large linear array of N antenna elements using only three or five feed points and phase shifters and still achieving beam switching. The idea consists of drastically reducing the number of input points by interlacing a small numer of serially fed subarrays which are suitably phased. This so-called interlaced phased array (IPA) concept was tested using an array of 15 four-element Yagi antennas with a spacing equal to 0.8 wavelengths and found feasible. Some of the distinct advantages of the IPA in comparison with a conventional system of beam switching are reduced power loss, reduced phasing errors, reduced cost, increased reliability resulting from greatly reduced number of phase shifters, and better symmetry of off-zenith beams     

Indirect Controlled Phased Source

We propose here a novel phase controllable oscillator to realize phase shift for the phased array. The phase of the oscillator is controlled by the phase of reference frequency of a phase locked loop. Since the reference frequency is usually lower than 100MHz, the phase shifting can be much easier, have a lower cost, and be more accurate than that in microwave phase shifters. A four-element scanning array antenna using this novel phase control technique is demonstrated with a scanning range of plusmn40deg in this letter     

Millimeter wave components for electronically controllable antennas

Many present and future military and commercial systems operating at millimeter wave frequencies require the use of sophisticated electronically controllable antennas for maximum capability and flexibility. Electronic control of the antenna pattern is provided by electronically switchable phase control of each radiating element such as that achieved in phased array antennas or via electronically reconfigurable antenna feeds referred to as beam forming networks (BFN). Multibeam antennas provided by BFN'S can be realized using switches, variable power dividers (VPD), and phase shifters. Ferrite materials and associated application technology are being utilized to achieve these switchable RF control components at millimeter wave frequencies. The performance achievable in ferrite switchable circulators, variable power dividers and phase shifters in the frequency region from 20 to 100 GHz is discussed.     

Subreflectarrays for Reflector Surface Distortion Compensation

With the increasing interest in the applications of large deployable reflector antennas operating at high frequencies, the requirement on the reflector surface accuracy becomes more demanding. Thermal effects inevitably cause certain reflector surface distortions, thus degrading the overall antenna performance. This paper introduces a novel reflector surface distortion compensation technique using a subreflectarray and presents detailed discussions. A microstrip reflectarray is used as a subreflector, illuminated by a primary feed. By properly adjusting the additional phase shift provided by the subreflectarray, the aperture phase errors caused by the main reflector surface distortions are compensated, resulting in a considerably improved antenna performance. As an example, a distorted 20-m offset parabolic reflector antenna operating at X-band is successfully compensated by a subreflectarray, and the simulation results are compared with those obtained by array feed and shaped subreflector compensation techniques. The microstrip subreflectarray is low-profile, lightweight, and cost-effective. Only one primary feed is required, and a reconfigurable design can be achieved if electronically reconfigurable reflectarray elements are adopted.      

A Novel Methodology to Feed Phased Array Antennas

A new methodology to design beam-forming networks (BFN) to feed antenna arrays is introduced. Using this methodology is feasible to reduce the complexity of the associate control of a phased array, since, an N by N antenna array could be controlled to steer the beam using four phase shifters instead of the N² conventionally used. A prototype was designed, built and measured as proof of concept. The prototype consists on 3 by 3 Quasi-Yagi antennas fed by four input-ports. The measurements show that the main beam of an antenna array fed by this BFN can be steered to any desired direction.     

有源相控阵天线瞬时宽带性能改善研究

采用无色散特性的模拟或数字移相器会导致天线波束指向随频率发生变化,即相控阵天线的孔径效应。工程上一般在子阵级别上采用色散特性的实时延迟线拓展相控阵天线瞬时带宽,但是子阵级延时量化误差会产生周期性栅瓣,导致天线副瓣性能恶化。文中提出在通道(或多通道收发组件)上设置小位延迟线、与子阵级大位延时线叠加使用,消除或改善子阵级延时误差造成的性能恶化。结合X波段有源二维阵列天线,对单元级、子阵级、子阵+单元两级三种情况进行了仿真。仿真结果表明,子阵+单元两级延时方法在扩展相控阵天线瞬时带宽的同时,能明显改善相控阵天线的副瓣特性,且具有较强的工程可实现性。     

光控相控阵天线中的光实时延时技术

讨论了光电子技术在宽带宽角扫描相控阵雷达中的应用和优点,介绍了光控相控阵天线的工作原理和发展状况,详述了不同光实时延时线(OTTD)的主要实现方法和技术特点,着重分析了一种可实用的基于光纤和光开关切换的OTTD的设计方法,并讨论了OTTD的性能指标对天线系统性能的影响,最后给出了在子阵OTTD和阵元移相器联合波控方法下的近场实验测试结果,验证了OTTD对相控阵天线宽带宽角扫描性能的改善.