scispace - formally typeset
Search or ask a question
Journal ArticleDOI

A study of the diffraction and blockage effects on the efficiency of the Cassegrain antenna

01 Jan 1984-Canadian Electrical Engineering Journal (IEEE)-Vol. 9, Iss: 1, pp 10-15
TL;DR: In this paper, the diffraction and blockage efficiencies of the conventional Cassegrain antenna are calculated by using the uniform geometrical theory of diffraction, and physical optics.
Abstract: The diffraction and blockage efficiencies of the conventional Cassegrain antenna are calculated by using the uniform geometrical theory of diffraction and physical optics. The various subefficiency terms corresponding to different diffraction fields are tabulated for a typical antenna and the results are discussed. Design curves that provide the aperture efficiency value as a function of main reflector diameter, subreflector diameter and the feed illumination taper are presented.
Citations
More filters
Journal ArticleDOI
TL;DR: Results of the analysis given in this paper agree well with rigorous computations based on physical optics analysis of the antenna radiation.
Abstract: 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.

107 citations

Journal ArticleDOI
TL;DR: In this paper, simplified design and analysis equations for multiple-beam reflector antennas based on the Gaussian-beam analysis of the primary and secondary patterns are presented for the quick design and performance analysis in terms of the coverage-area directivity and the inter-beam isolation of multiplebeam antenna systems.
Abstract: Simplified design and analysis equations are presented for multiple-beam reflector antennas based on the Gaussian-beam analysis of the primary and secondary patterns. The derived equations are useful for the quick design and performance analysis in terms of the coverage-area directivity and the inter-beam isolation of multiple-beam antenna systems. Results of the analysis given in this paper agree well with rigorous computations based on physical-optics analysis of the reflector-antenna radiation patterns. Extension of the analysis to multiple-beam lens antennas, and to shaped/contoured-beam antennas, is also presented.

79 citations

Journal ArticleDOI
TL;DR: In this article, a modified template for shaped-beam satellite antenna patterns is proposed for use in orbit-planning studies of a fixed satellite service, which includes the effects of beam scanning, aperture blockage, and surface errors.
Abstract: A modified template is proposed for shaped-beam satellite antenna patterns for use in orbit-planning studies of a fixed satellite service. Based on a previously discussed simple model, the template now includes the effects of beam scanning, aperture blockage, and surface errors. It is found to agree well with the measured data on current satellites and is a reasonable upper bound specification for future satellite antennas. >

4 citations

Proceedings ArticleDOI
08 Jul 2018
TL;DR: In this paper, a dual-polarized Ka-band monopulse antenna with a non-standard reflector profile is presented, which can be used to generate a desired aperture illumination that classical parabolic reflector surfaces cannot provide.
Abstract: MIT LL is developing a small dual-polarized Ka-band monopulse antenna, which has very challenging specifications imposed on the radiator that require a sophisticated and efficient reflector antenna design. Reflector shaping is a technique that can be used to create a specific non-standard reflector profile to generate a desired aperture illumination that classical parabolic reflector surfaces cannot provide. A comparison with the classical Cassegrain parabolic reflector antenna will be reviewed and results discussed for the antenna design approach utilized at MIT LL. Measured data will be presented for the prototype antenna that was constructed.

4 citations


Cites background from "A study of the diffraction and bloc..."

  • ...This is true for all classical Cassegrain antenna designs, however, it is not as significant of an issue for high-gain reflector antennas (50 dBi or greater antenna gain) due to larger main reflector aperture sizes where the blockage becomes insignificant in terms of the percentage of the rays affected [1]....

    [...]

Journal ArticleDOI
01 Apr 1988
TL;DR: In this paper, the authors give an overview of the activity in the areas of reflector antennas and feeds in Norway since 1978, including cylindrical, symmetrical, spherical, offset, single and dual-reflectors, and primary dipole feeds.
Abstract: This article gives an overview of the activity in the areas of reflector antennas and feeds in Norway since 1978. The activity includes cylindrical, symmetrical, spherical, offset, single- and dual-reflectors, and primary dipole feeds, waveguide feeds, hybrid-mode feeds, lens feeds and microstrip antennas. The work has resulted in industrial applications and a number of articles in international journals.

3 citations

References
More filters
Journal ArticleDOI
01 Nov 1974
TL;DR: In this article, a compact dyadic diffraction coefficient for electromagnetic waves obliquely incident on a curved edse formed by perfectly conducting curved plane surfaces is obtained, which is based on Keller's method of the canonical problem, which in this case is the perfectly conducting wedge illuminated by cylindrical, conical, and spherical waves.
Abstract: A compact dyadic diffraction coefficient for electromagnetic waves obliquely incident on a curved edse formed by perfectly conducting curved ot plane surfaces is obtained. This diffraction coefficient remains valid in the transition regions adjacent to shadow and reflection boundaries, where the diffraction coefficients of Keller's original theory fail. Our method is based on Keller's method of the canonical problem, which in this case is the perfectly conducting wedge illuminated by plane, cylindrical, conical, and spherical waves. When the proper ray-fixed coordinate system is introduced, the dyadic diffraction coefficient for the wedge is found to be the sum of only two dyads, and it is shown that this is also true for the dyadic diffraction coefficients of higher order edges. One dyad contains the acoustic soft diffraction coefficient; the other dyad contains the acoustic hard diffraction coefficient. The expressions for the acoustic wedge diffraction coefficients contain Fresenel integrals, which ensure that the total field is continuous at shadow and reflection boundaries. The diffraction coefficients have the same form for the different types of edge illumination; only the arguments of the Fresnel integrals are different. Since diffraction is a local phenomenon, and locally the curved edge structure is wedge shaped, this result is readily extended to the curved wedge. It is interesting that even though the polarizations and the wavefront curvatures of the incident, reflected, and diffracted waves are markedly different, the total field calculated from this high-frequency solution for the curved wedge is continuous at shadow and reflection boundaries.

2,582 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used the geometrical theory of diffraction to obtain the backscattered field for plane-wave incidence on a target with particular emphasis on those regions that are usually avoided, namely, the caustic region and its immediate vicinity.
Abstract: The fields diffracted by a body made up of finite axially symmetric cone frustums are obtained using the concepts of the geometrical theory of diffraction. The backscattered field for plane-wave incidence on such a target is obtained with particular emphasis on those regions that are usually avoided, namely, the caustic region and its immediate vicinity. The method makes use of equivalent electric and magnetic current sources which are incorporated in the geometrical theory of diffraction. This solution is such that it is readily incorporated in a general computer program, rather than requiring that a new program be written for each shape. Several results, such as the cone, the cylinder and the conically capped cylinder, are given. In addition, the method is readily applied to antenna problems. An example which is reported consists of the radiation by a stub over a circular ground plane. This present theory yields quite good agreement with experimental results reported by Lopez, whereas the original theory given by Lopez is in error by as much as 10 dB.

191 citations

Journal ArticleDOI
TL;DR: The edge diffraction coefficients of Kouyoumjian and Pathak, when applied to edges in curved screens produce discontinuities in the diffracted fields which do not coincide with those of the specular field on the concave side of the screen as mentioned in this paper.
Abstract: The edge diffraction coefficients of Kouyoumjian and Pathak, when applied to edges in curved screens produce discontinuities in the diffracted fields which do not coincide with those of the specular field on the concave side of the screen. In regions where coincidence occurs the discontinuities add, rather than cancel. The field calculated from the diffraction coefficient violates the principle of reciprocity.

23 citations

Proceedings ArticleDOI
24 May 1982

2 citations