Electromagnetic bandgap phased array antenna controlled by piezoelectric transducer

The optimal performance of a phased array antenna controlled by a piezoelectric transducer, having an electromagnetic bandgap (EBG) structure in the ground plane of the feed microstrip lines, is illustrated. The EBG presence increases by about 10/spl deg/ the beam scanning angle achieved by the multiline phase shifter.     

Electromechanical controlled phased array dumbbell EBG beam steerer

A steerable phased array antenna driven mechanically is realized by utilizing the variation of dumbbell electromagnetic bandgap (EBG) structures. The variation takes place under the feed line of a 4-element array that gives the change in relative phase shift. The phase shift achieved from different shaping combinations of EBGs shifting under the feed lines. The feed lines are connected with four microstrip patches to yield a 4-element phased array antenna. The mechanical controlled pattern shapes of phase array antenna are simulated in electromagnetic (EM) software Zeland IE3D. Finally the design is fabricated with the help of optical lithography. It can be seen that the beam steering angle can be controlled mechanically without phase shifter and PIN switches.     

Custom modes for microstrip phased array analysis

Custom modes for the patch current in an infinite microstrip phased array are derived. Compared to the set of subdomain basis functions normally used for arbitrarily shaped patches these `Fourier modes' reduce the number of unknowns by one to two orders of magnitude. This should make them particularly useful for the analysis of finite arrays     

Intermodulation in multiple fixed beam distributed amplifier phased array antenna systems

In the recent development of phased array/distributed amplifier systems for application to mobile satellite or thin route communication systems, the intermodulation (IM) generated by the element amplifiers is spatially dispersed in such a way that some of the IM radiated energy falls outside the intended beam area. In addition, some of the IM falling inside the beam area has frequencies different from the carriers intended for that area. It is known that for fixed beam systems with frequency reuse, an average IM noise reduction of several dB can be realized. In the specific case under investigation, of four beams, nine frequencies and 12 carriers (1-33 frequency reuse factor), an IM improvement of about 2-0 dB is realized. The improvement in carrier-to-IM-noise ratio can be applied to increase system capacity, or for given capacity it can be used to reduce RF power amplifier back-off, which can be translated into a reduction of spacecraft prime power requirement. The considerable advantage gained from the multiple beam distributed amplifier approach makes it worthwhile to explore the workings of such a system and other benefits it may offer. One of the benefits is a common RF power pool for all carriers and beams, and the other is the spatial dispersion of intermodulation (IM). A satellite multiple beam pattern and the spatial dispersion of IM products are shown in Figure 1.     

Rigorous analysis of microstrip phased array antennas using a new FDTD method

A finite-difference time-domain (FDTD) algorithm for radiating antennas that involve multiple, phased excitation sources is presented. The algorithm has the potential to analyse phased array antennas in the time domain. The authors apply it to a two-element microstrip antenna (MSA) phased array on a finite substrate, and compare the results as gained with an existing method and experiments.<>     

Analysis of wraparound microstrip phased array by infinite arrayapproach

A moment method analysis of an infinite array of wraparound microstrip antennas fed with idealized current probes on a cylindrical body is presented. The integral equation is formulated through the use of periodic grounded dielectric slab Green's function. The method accounts for the blind angles and allows efficient computation of the reflection coefficient at all other angles. Illustrative results are given     

A 7.5-GHz microstrip phased array for aircraft-to-satellite communication

The demand for high-gain full-hemisphere coverage for aircraft-to-satellite communications is ever increasing. Many approaches to this problem have been investigated, including a parabolic dish under a radome and the more conformal hybrid-scan array under a radome. Both are heavy and protrude a significant distance from the aircraft skin. An alternative solution to the problem may be a completely conformal lightweight microstrip phased array.     

Design of Rotman lens for beamsteering of 94 GHz antenna array

The design and development of a Rotman lens for operation at 94 GHz which feeds an antenna array for beamsteering applications is presented. The construction is completely realised in waveguide technology. The lens consists of 15 beam ports covering a scan range of /spl plusmn/23.3/spl deg/ in steps of 3.3/spl deg/ and 10 array ports connected via phase compensating transmission lines to a linear antenna array. Experimental results are compared with theoretical calculations.     

A study of steering capability of a microstrip phased array using inter-injection locked oscillators

An innovative, phase coherent, power combining method, known as inter-injection locking applied to linear limited scan phased arrays is investigated. In this novel method, each antenna element in the array is supplied by power from a separate oscillator. However, the oscillator phases are allowed to be synthesized coherently by means of a coupling network and injection currents, being the input controls to the system of coupled phases oscillators. The inter-injection-locked phased arrays studied in this paper provide more design freedom than conventional phased arrays. They also result in systems more adapted to solid state monolithic integration technology.     

X波段光控相控阵雷达技术

基于现有的器件提出了X波段光控相控阵雷达的设计方案,对光信号收发以及OTTD(Optical True Time Delay)的实现方案进行了探讨.采用光纤技术的X波段光控相控阵雷达通过引入光实时延迟线OTTD,减轻了传统相控阵雷达因渡越时间和孔径效应对信号瞬时带宽的限制,实现了宽带宽角扫描.     

Optical beam forming techniques for phased array antennas

Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are 1) the fiber replacement of conventional RF phased array distribution and control components, 2) spatial beam forming, and 3) optical beam splitting techniques. Two novel optical beam forming approaches, i.e., the spatial beam forming with a “smart pixel” spatial light modulator (SLM) and the optical beam splitting approaches are conceived with integrated quasi-optical components. Also presented are the transmit and receive array architectures with the new SLM.     

Programmable dispersion matrix using Bragg fibre grating foroptically controlled phased array antennas

A programmable dispersion matrix implemented with Bragg fibre gratings is demonstrated in conjunction with a multiwavelength laser source for use in optically controlled phased array antennas. Relative time delays are experimentally measured using a prototype programmable dispersion matrix with 2 bit resolution and the results agree well with the theoretical prediction     

Finite phased array of microstrip patch antennas: the infinitearray approach

An efficient method of analysis of large infinite arrays based on a convolution technique that allows one to obtain the finite array characteristics from the infinite array results is presented. The edge effects are taken into account by convoluting the infinite array results with the proper current amplitude window on the array. The method is based on the use of Poisson's sum formula in the case of finite arrays applied here to microstrip antennas. It is an approximate technique that can be assimilated into a perturbation method     

Frequency-controlled beam steering of surface acoustic waves using a stepped transducer array

Using stepped arrays of transducers, the direction of propagation of surface acoustic waves can be controlled by varying the input frequency. This effect has applications in maintaining the optimum Bragg angle in acousto-optic devices for integrated optics. The measured beam-steering angle for a given frequency change follows the theory of Pinnow, where anisotropy effects are taken into account.     

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     

New array codes for multiple phased burst correction

An optimal family of array codes over GF(q) for correcting multiple phased burst errors and erasures, where each phased burst corresponds to an erroneous or erased column in a code array, is introduced. As for erasures, these array codes have an efficient decoding algorithm which avoids multiplications (or divisions) over extension fields, replacing these operations with cyclic shifts of vectors over GF(q). The erasure decoding algorithm can be adapted easily to handle single column errors as well. The codes are characterized geometrically by means of parity constraints along certain diagonal lines in each code array, thus generalizing a previously known construction for the special case of two erasures. Algebraically, they can be interpreted as Reed-Solomon codes. When q is primitive in GF(q), the resulting codes become (conventional) Reed-Solomon codes of length P over GF(q^p-1), in which case the new erasure decoding technique can be incorporated into the Berlekamp-Massey algorithm, yielding a faster way to compute the values of any prescribed number of errors     

舰载相控阵雷达的自适应波束扫描技术优化

为了提高舰载相控阵雷达的目标定位检测能力,提出一种基于二维波束域加权谱峰搜索的舰载相控阵雷达自适应波束扫描算法.采用均匀阵列构建舰载相控阵雷达相干分布源模型,以目标的方位及目标的扩展角为二维参量,建立点目标信号源的多亮点特征分布阵列,用点目标来模拟空间的分布式目标,采用自适应波束形成算法进行目标的方位、距离及DOA的联合参量估计,采用二维波束域加权谱峰搜索方法实现远场分布式目标的空间谱特征提取,根据谱峰的位置求出目标方位,实现对目标的自适应波束扫描,提高目标的定位检测能力.仿真结果表明,采用该方法进行舰载相控阵雷达的自适应波束扫描,对目标的定位准确率较高,检测性能较好,波束输出具有很好的旁瓣抑制能力,说明抗干扰能力较强.     

A low-cost 8 to 26.5 GHz phased array antenna using a piezoelectrictransducer controlled phase shifter

A new phased array antenna of wide bandwidth and good beam scanning angle has been developed using a low cost multiline phase shifter controlled by a piezoelectric transducer (PET) and a stripline fed Vivaldi antenna array. The multiline progressive PET phase shifter has a low perturbation loss of less than 2 dB and a total loss of less than 4 dB up to 40 GHz with a maximum phase shift of 480°. The proposed phased array antenna consists of four E- or H-plane Vivaldi antennas, a PET phase shifter, and a power divider. The phased array shows a wide beam scanning capability of ±27° over a wide bandwidth from 8 to 26.5 GHz covering X, Ku, and K bands     

Cavity backed microstrip patch array feed for multiple beamapplications

Multiple beam antennas use reflectors with several feeds at offset locations in the focal plane. The complete feed array tends to be bulky and heavy, hence, to alleviate this, microstrip patch arrays have been used as feed elements. However, a power division circuit becomes necessary for the patches which increases losses. A patch array backed by a cylindrical cavity is proposed which eliminates this lossy circuit. An additional feature is that the beamwidths in various planes may be controlled to a certain extent by varying the interelement spacing. The test results of the proposed feed are presented and discussed; the feed seems suitable for use in multiple-beam applications