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1.
This paper presents the parametric design and analysis of multiple-beam reflector-antenna systems employed for satellite communications. It is based on extending the earlier work of Rao (see IEEE Antennas and Propagation Magazine, vol.41, no.4, p.53-59,1999) by taking into account the efficiency of the horn and pointing error of the satellite in the design of the multiple-beam antennas (MBAs), and by analyzing the edge-of-coverage directivity and co-polar isolation (C/I) performance. Design and analysis equations are developed for the multiple-beam antennas using offset parabolic-reflector antennas by including various design parameters such as the number of reflectors, the number of frequency cells, the focal-length-to-diameter (F/D) ratio, the horn efficiency, and the pointing error. The analysis employs a quasi-Gaussian beam representation for the primary and secondary patterns in order to take into account the effect of the sidelobes. Results of the analysis given in this paper agree well with rigorous computations based on physical optics analysis of the antenna radiation. Design curves showing the impact of horn efficiency on the C/I performance of multiple-beam antennas are presented for various frequency-reuse schemes. 相似文献
2.
The minimum directivity of a multiple-beam antenna is an important design parameter of the related communications system. This parameter is a function of the spacing between the feeds of a focusing device. In this communication it is shown that the minimum directivity can be optimized by the proper choice of feed spacing. 相似文献
3.
Adaptive nulling with multiple-beam antennas 总被引:2,自引:0,他引:2
Some of the more prominent features of an Applebaum-Howells type adaptive nulling processor when used in conjunction with a multiple-beam antenna operating over the earth field of view at synchronous altitude are discussed. Incorporation of this scheme with a multiple-beam antenna allows for the use of a large filled aperture in order to obtain pattern shaping capabilities over a limited field of view while keeping the number of antenna output ports at a tractable number. It also leads to a partial decoupling of the adaptive feedback loops, a property which can be exploited to provide significant improvements in the dynamic performance of the control system. Three techniques for accomplishing this improved dynamic performance particularly applicable to multiple-beam antennas are considered. 相似文献
4.
Diffraction analysis of frequency selective reflector antennas 总被引:2,自引:0,他引:2
A unified computational technique which allows the incorporation of the curved frequency selective surface (FSS) geometry in the computation of a dual-reflector-antenna radiation pattern is presented. The scattered fields from a illuminated FSS reflector are formalized using Huygens' principle in such a way that the `reflecting' and the `transparent' FSS subreflector cases are treated identically and the thickness of the FSS subreflector remains arbitrary. The analysis utilizes local surface coordinates to describe the reflection/transmission matrices of the FSS subreflector, assuming that these matrices are available. In most cases the local tangent plane may be used to approximate the plane of the FSS in the local coordinate surface of the reflector. The way in which the local curved coordinate system can be introduced in the diffraction modeling of FSS reflectors and its importance in accurately predicting the sidelobe and cross-polarization levels are demonstrated. Results of numerical simulations are presented for several FSS subreflector configurations 相似文献
5.
Lorenzo J.A.M. Pino A.G. Vega I. Arias M. Rubinos O. 《Antennas and Propagation Magazine, IEEE》2005,47(2):92-100
The aim of this work is to present the ICARA (induced-current analysis of reflector antennas) software, which is able to predict the behavior of reflector antennas using the physical optics method. The software offers different options for antenna configurations, single and array feed models, and far-field or aperture-field analysis. 相似文献
6.
A formula for beam coupling is obtained which relates the coupling to the value of the polar diagram calculated from the product of the aperture fields of the individual beams at a position related to the angular beam separation. 相似文献
7.
Exact sampling approach for reflector antennas analysis 总被引:1,自引:0,他引:1
A new method for computing the far field of a possibly shaped or deformed reflector antenna based on a sampling representation of the radiation integral is presented. Using a projection technique the required samples can be efficiently computed using a two-dimensional fast Fourier transform (FFT), whereas the radiated field is reconstructed via standard sampling expansion. Numerical examples and computation time analysis are reported showing the effectiveness of the approach particularly for deformed reflectors and/or plane-cut field evaluation. 相似文献
8.
Although many reflector antennas possess circular projected apertures, there are recent satellite and ground antenna applications for which it is desirable to employ reflectors with elliptical apertures. Here a modification of the Jacobi-Bessel expansion is presented for the diffraction analysis of reflectors with elliptical apertures. A comparative study is also performed between this modified Jacobi-Bessel algorithm and the one which uses the Jacobi-Bessel expansion over a circumscribing circular region. Numerical results are presented for offset reflectors with elliptical and circular apertures and the improved convergence properties of the modified algorithm are highlighted. 相似文献
9.
卫星阵馈反射面多波束天线赋形波束的性能分析 总被引:2,自引:0,他引:2
该文主要对赋形波束的性能与波束宽度和波束间隔间的关系进行了一般性的研究。首先提出4个能够描述赋形波束性能好坏的性能指标。然后给出波束赋形问题的数学模型,这个模型建立了赋形波束的性能指标与波束宽度和波束间隔间的关系。接着应用泛函分析理论推导了波束赋形问题的一般解,同时通过对这个一般解的讨论,从信号与系统的角度阐明了波束赋形的机理。最后通过一个实际的例子分析了波束赋形的两个参数波束宽度和波束间隔与性能指标之间的变化关系,并提出了选择最佳波束宽度和波束间隔的简易方法。 相似文献
10.
Attaching blinders to the sides of pyramidal horn reflector antennas and other large aperture antennas is one method of controlling high sidelobes for horizontal polarization. This paper describes analysis and design procedures for arriving at a useful multiple-edge blinder for reducing undesirable sidelobes of a pyramidal horn reflector antenna. Several blinders have been designed and tested for use with a pyramidal horn reflector antenna. They are directed at reducing a high sidelobe near90deg in the azimuth plane where levels (referred to the main lobe) of -52 dB at 3.74 GHz and -58 dB at 6.325 GHz are presently typical. A 14-edge blinder designed using these techniques reduced these levels by 20 dB at 3.74 GHz and 12 dB at 6.325 GHz and did not significantly degrade antenna performance for other angles and other polarizations. 相似文献
11.
A general theory of reflector antennas loaded by surface impedances is presented. Spatial variation of primary illumination is taken into account using a generalized slope diffraction coefficient. The theory is experimentally checked on surface loaded square plate scatterers and then used for computing the radiation diagram of parabolic and hyperbolic dishes. Computer programs and computed diagrams refer to the case of focal illumination and negligible tapering of primary illumination. 相似文献
12.
Alan Walter Rudge 《电信纪事》1984,39(1-2):3-33
The paper provides a tutorial review of a number of offset parabolic reflector configurations including both single and double-reflector geometries. The author commences by describing some basic techniques which can be applied to predict the vector radiation fields and provides some indication of the validity of these methods. The formulation of a relatively simple analytical model for the offset reflector antenna is described based upon the physical-optics approximation. The electrical performance of the single-offset reflector is examined by comparison of predicted and measured data. The particular problems arising from the choice of polarisation and reflector dimensions are highlighted, and some practical applications involving multiplebeams, shaped and contoured beams, monopulse tracking and low sidelobes are briefly reviewed. Practical primary-feeds for offset-reflector antennas are discussed and the matched-feed concept is outlined, the matching of the electric fields in the primary-feed aperture to the reflector focal fields being illustrated. The advantages and disadvantages of dual-reflector antennas are then examined, with particular emphasis upon the open Cassegrainian configuration and the optimised doubleoffset configuration which offers, in principle, both freedom from blockage and low levels of cross-polarised radiation. 相似文献
13.
An iterative method is presented to find the reflector profile which minimises the mean-square error between a scattered and a desired field, thereby achieving pattern synthesis. This technique is applied to 3-dimensional circulary symmetric systems for either field- or power-pattern synthesis. Theoretical and experimental results are given for the problem of synthesising a uniform-amplitude sector beam between 20° and 66°. 相似文献
14.
The characteristics of the astigmatic phase error in large parabolic reflector antennas are described. A procedure for focusing an antenna and diagnosing the presence and degree of astigmatism is given. 相似文献
15.
Smart antenna is considered as one of the most effective means for enhancing wireless system capacity. When fractional loading is accompanied with slow-frequency hopping (SFH), soft capacity can be realized in time-division multiple access (TDMA) wireless networks. Then, the interference reduction due to smart antennas, power control, and discontinuous transmission can be directly translated into capacity gain. This paper addresses the capacity gain due to multiple-beam (MB) smart antennas in TDMA wireless systems with soft capacity. The system capacity is determined analytically and by simulation. MB smart antennas with practical antenna pattern are used in this study. Perfect power control and discontinuous transmission are assumed in the simulation and the theoretical analysis. A novel call admission control algorithm is proposed to enhance the system capacity without degrading the signal quality. The TDMA system is assumed to be global system for mobile communications (GSM)-like, however, the analysis can be extended and applied to other TDMA systems 相似文献
16.
A full-wave analysis is presented of offset reflector antennas with polarization grids which uses the equivalent grating approach proposed by the authors (ibid., vol.AP-35, p.367-71, Apr. 1987). Two types of antenna are compared: one has a parallel straight strip grating (grid A) and the other has a curved strip grating (grid B) whose pattern is designed so that the antenna system does not generate a cross-polarized component. The key future method is the definition of the equivalent grid. This method quantitatively evaluates the scattering, includes a physical interpretation of the phenomena and gives a physical interpretation of the phenomena and gives a suggestion for the design of the strip patterns. Cross-population suppression effects are quantitatively evaluated as functions of the strip parameters, the size and the location of the grid. It is noted that the cross-polar peaks of the patterns with grid A move with the tilt angle of the grid. The mechanism of this movement is also explained 相似文献
17.
Reflector antennas with mesh surfaces are used extensively in many satellite and ground antenna systems. A strip-aperture modeling of commonly used mesh surfaces is presented which provides considerable versatility in characterizing the mesh cells. The mesh transmission coefficients are constructed using a Floquet-modal expansion in conjuction with two dominant aperture modes. To account for the mesh local coordinates, the Eulerian angle transformation is invoked to obtain the total induced current on the curved reflector surface. General formulas are presented to show how the solid surface induced current is modified due to the transmission through the mesh. The effects of a variety of mesh configurations on both the co-polar and cross-polar patterns of reflector antennas are studied by numerically evaluating the vector diffraction integral using the Jacobi-Bessel expansion. For some special cases, a comparison is made with the results of the commonly used wire-grid formulation. Many of the numerical data are tailored to the dimensions of a conceptually designed mesh deployable offset reflector of the land mobile satellite system (LMSS). 相似文献
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