The uniform geometrical theory of diffraction (UGTD) is employed to analyze the far-field radiation patterns of a prime focus paraboloid with a cylindrical shroud. The blockage of the aperture illumination of the dish by the gooseneck and the primary feed is also taken into account in the analysis. Far-field radiation patterns (for 0° ≤ θ ≤ 180°), calculated for a typical prime focus paraboloid with 2 m aperture diameter, designed and fabricated, are compared with the experimentally derived patterns at 8.8 GHz in the E- and H-planes. There is a satisfactory agreement between the two results. Copyright © 1983 by The Institute of Electrical and Electronics Engineers, Inc.

M. S. Narasimhan

ANTENNAS, PARABOLIC

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IIT Madras

GTD analysis of the radiation patterns of a prime focus paraboloid with shroud

IEEE Transactions on Antennas and Propagation

The uniform geometrical theory of diffraction (UGTD) has been applied successfully to analyze the near-field patterns of a prime-focus paraboloid. In order to establish the validity of the analysis, near-field amplitude and phase patterns have been computed over the principal planes at several observation distances for a typical prime-focus paraboloid. These calculations compare very favorably with the corresponding results obtained numerically with the aid of Silver's near-field aperture integration formula. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc.

GTD Analysis of the Near-Field Patterns of a Prime-Focus Symmetric Paraboloidal Reflector Antenna

A geometrical theory of diffraction (GTD) analysis of the principal plane far-field radiation patterns of a hyperboloidal sub-reflector with a conical flange attachment (HWF) fed by a primary feed located at its focus is presented. While using the uniform geometrical theory of diffraction (UGTD) for evaluating the nonaxial fields, the method of equivalent currents is used in the axial region. In this paper, both the diffraction by the wedge formed between the hyperboloid and the conical flange and the diffraction by the edge of the flange are considered. While considering the diffraction by the edge due to the diffracted ray from the wedge in the H-plane, the slope diffraction technique has been used. The computed diffracted far-fields of a typical HWF illuminated by a high performance primary feed shows good agreement with the available measured data and with the results based on the method of physical optics (PO). The sharp cutoff and the low spillover characteristics of the HWF are highlighted by comparing its radiation pattern with that of a hyperboloid without a flange. Further, the effects of the different parameters of the HWF on its radiation pattern are also studied and plotted, so that these results can be utilized in the design of the HWF for a specific requirement. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc.

Journal	IEEE Transactions on Antennas and Propagation
ISSN	0018926X
Open Access	No