摘要:

A recently developed antenna pattern reconstruction technique using the nonuniform sampling algorithm is able to construct the antenna far-field patterns from a set of non-uniformly distributed amplitude and phase samples. This paper presents the application of this technique to an actual antenna measurement performed at JPL. The 1.47-meter Viking and a 1-meter reflectors operating at X-band were both measured. A conical-cut approach is used to generate nonuniformly distributed samples. The far-field patterns of these two antennas are reconstructed from the measured data using a developed computer program based on the nonuniform sampling algorithm. An overlapping “Window Concept” is also applied in the far-field reconstruction process to avoid measurement error spreading. The results of the reconstructed patterns are compared with the standard azimuth-cut patterns. The effects of selection of various phase reference points in applying the nonuniform sampling technique are demonstrated through a numerical simulation of the Viking antenna. This technique is anticipated to be used for the measurement of large antennas.

ISSN:0272-6343    

DOI:10.1080/02726348608915217

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The radiation characteristics of radial rib reflector antennas are studied. This type of antenna can be used as a large deployable satellite antenna. The radiation patterns of a axi-symmetric reflector are computed using both an exact physical optics analysis and a simplified approximate analysis in order to understand the behaviour of the rib-related sidelobes which have a cyclic behaviour in the azimuthal direction. A parametric study is conducted. A shaped sub-reflector is designed using diffraction profile synthesis to compensate for some of the errors introduced by the main radial rib reflector.

ISSN:0272-6343    

DOI:10.1080/02726348608915218

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Hybrid mode horns are of considerable practical importance, especially as feeds for lens and reflector antennas. In this tutorial review the boundary conditions necessary to support hybrid modes in round waveguide are derived. Expressions for the field components in HE1nand EH1nmodes are given and from these the transverse field over the open mouth of the guide is found. The Fourier transform of this field is then used to calculate far field radiation patterns. Solutions to the characteristic equation for hybrid modes are indicated and the dispersion characteristics for balanced modes are presented graphically. Finally, a brief discussion of dielectric-lined waveguide is given and asymptotic solutions are developed to show that nearly balanced HE11and EH11modes can exist over a limited frequency range when the dielectric is lossless, but over an unlimited range when the dielectric is highly lossy.

ISSN:0272-6343    

DOI:10.1080/02726348608915219

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The radiation characteristics of small microstrip arrays is investigated including the mutual coupling effects among the array elements. The mutual coupling of the elements is determined using the reaction theorem, which provides both array patterns and the active Impedances of the elements. The method is then used to study a 19-element array for MSAT application. For the array elements circular patch microstrip antennas are used and optimized to give satisfactory circularly polarized radiation. For the 19-element array, it is shown that the array gain decreases by scanning the array beam towards the endfire direction and a peak gain of 13.73 dBi. is obtained at an elevation angle of 57 degrees. Further scanning of the beam, towards lower elevation angles, reduces the array gain further.

ISSN:0272-6343    

DOI:10.1080/02726348608915220

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The offset dual parabolic cylindrical reflectors are analyzed. They generally produce elliptical beam patterns with unequal beamwidths in the two principal planes. The dependence of the principal plane beamwidths, the peak cross-polarization level, the antenna gain and the first sidelobe level on the antenna geometrical parameters, and in particular the offset angle, is studied. The main effect of the offset angle is increasing the cross-polarization level. However, for any offset configuration, the angle between the two reflectors has a strong effect on the cross-polarization. Optimizing this angle, the peak cross-polarization may become negligibly small, and as low as -60dB. A design procedure for such an offset configuration is provided and a design example Is given.

ISSN:0272-6343    

DOI:10.1080/02726348608915221

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In the use of satellite positioning systems such as the Global Positioning System (GPS) significant errors can be introduced into the indicated position through the properties of the antenna structure. Of particular interest are the phase characteristics of the antenna as a function of observation angle. The microstrip antenna features a rugged, low profile and light weight construction making it an ideal choice for practical applications, but positioning accuracy may be limited by the phase perturbations introduced by the microstrip mounting surface.

ISSN:0272-6343    

DOI:10.1080/02726348608915222

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor