Reflector (antenna)

About: Reflector (antenna) is a research topic. Over the lifetime, 28730 publications have been published within this topic receiving 212618 citations.

FFT applications to plane-polar near-field antenna measurements

Abstract: The four-point bivariate Lagrange interpolation algorithm was applied to near-field antenna data measured in a plane-polar facility. The results were sufficiently accurate to permit the use of the FFT (fast Fourier transform) algorithm to calculate the far-field patterns of the antenna. Good agreement was obtained between the far-field patterns as calculated by the Jacobi-Bessel and the FFT algorithms. The significant advantage in using the FFT is in the calculation of the principal plane cuts, which may be made very quickly. Also, the application of the FFT algorithm directly to the near-field data was used to perform surface holographic diagnosis of a reflector antenna. The effects due to the focusing of the emergent beam from the reflector, as well as the effects of the information in the wide-angle regions, are shown. The use of the plane-polar near-field antenna test range has therefore been expanded to include these useful FFT applications. >

Synthesis of multireflector antennas by kinematic and dynamic ray tracing

Abstract: A technique for synthesizing reflector surfaces that transform a known input ray-field (e.g., the radiation field of a feed) to a desired output ray-field (e.g. an aperture distribution) is presented. The synthesis problem is reduced to solving linear equations by local biparabolic expansions of the reflector surfaces. Because the solution is easier to control, this is advantageous compared to existing techniques based on solving nonlinear differential equations. The condition to obtain low cross polarization can therefore be readily included, and the requirements for an exact solution to exist can be found clearly. The latter has been the subject of discussion in the literature for several years. The synthesis technique is applied to a shaped-offset dual-reflector antenna and to the proposed dual-reflector feed of the spherical reflector antenna in Arecibo. In both cases circular and elliptical apertures are considered. >

Imaging reflector arrangements to form a scanning beam using a small array

Abstract: To obtain the performance of a large aperture phased array, a small phased array is combined with a large main reflector and an imaging arrangement of smaller reflectors to form a large image of the small array over the main reflector. An electronically scanable antenna with a large aperture is thus obtained, using a small array. An attractive feature of the imaging arrangement is that the main reflector need not be fabricated accurately, since small imperfections can be corrected efficiently by the array. As an application, a 4.2-m diameter antenna is discussed for a 12–14 GHz satellite with a field of view of 3 degrees by 6 degrees required for coverage of the continental United States.

Plasma reflectors for electronic beam steering in radar systems

Abstract: The author describes investigations into methods of generating a planar plasma for use as a reflector for radar waves. The use of the plasma reflector could allow electronic beam steering at frequencies above what is generally viable for phased arrays. Three aspects of the planar plasma production are investigated: localization of the plasma, main plasma production, and long-term viability of the system. Possible applications include ship-based antennas at X-band, airborne antennas at 94 GHz, and space-based antennas at 60 GHz. The author discusses system considerations for the three potential radar configurations. Results and potential small-scale experiments to test various aspects of the concept are discussed. >

Surface diagnosis of large reflector antennas using microwave holographic metrology: An iterative approach

Abstract: The radiation pattern of an antenna can be significantly affected by reflector surface errors A minimization of losses due to surface inaccuracies is, therefore, required A suitable procedure for the determination of the deviations of the surface from its ideal geometry is based on the microwave holographic technique In this procedure, the complex pattern of the antenna is measured, and the Fourier transform relationship, existing between the radiation pattern and the function related to the current distribution on the reflector surface, is applied It is naturally desirable to limit the amount of measured data The present investigation is concerned with the concept of the Fourier transform relationship between the induced current and the far field It is demonstrated that the relationship, in general, can be interpreted as a summation of many Fourier transforms An iterative scheme is employed to continue the far-field pattern outside the measurement window