Correction to "Application Of Incremental Length Diffraction Coefficients To Calculate The Pattern Effects Of The Rim And Surface Cracks Of A Reflector Antenna"

Incremental length diffraction coefficients (ILDCs) for the half-plane are integrated around the rim of a paraboloid reflector antenna to obtain well-behaved far fields of the nonuniform current for all angles of observation. These far fields, when added to the physical optics far field, produce a more accurate total far field of the reflector. Excellent agreement with the far fields obtained from a method-of-moments solution to the electric field integral equation applied to a 20-wavelength-diameter reflector shows that the cross polarization, farther-out sidelobes, and fields near nulls of reflector antennas can be appreciably modified by the fields of the nonuniform currents. ILDCs are also used to investigate the effect of cracks on the surface of reflectors that can result from the imperfect fitting together of panels to form large reflectors. Three models of cracks are studied. Significant pattern effects are found, depending on the model and orientation of the cracks. >

[1]  The SNFGTD method and its accuracy , 1987 .

[2]  R. F. Millar.  An Approximate Theory of the Diffraction of an Electromagnetic Wave by an Aperture in a Plane Screen , 1956 .

[3]  A. Yaghjian,et al.  Equivalence of surface current and aperture field integrations for reflector antennas , 1984 .

[4]  R. F. Millar.  The Diffraction of an Electromagnetic Wave by a Circular Aperture , 1957 .

[5]  M. Hinders,et al.  Dual-series solution to scattering from a semicircular channel in a ground plane , 1991, IEEE Microwave and Guided Wave Letters.

[6]  J. Keller,et al.  Geometrical theory of diffraction. , 1962, Journal of the Optical Society of America.

[7]  G. Franceschetti,et al.  Recent developments in the analysis of reflector antennas. A review , 1986 .

[8]  A. Michaeli.  Equivalent edge currents for arbitrary aspects of observation , 1984 .

[9]  W. Braunbek,et al.  Neue Näherungsmethode für die Beugung am ebenen Schirm , 1950 .

[10]  A. P. Smolski,et al.  The interpanel gap scattering effect in a compact range , 1991 .

[11]  Arthur D. Yaghjian,et al.  Incremental Diffraction Coefficients for Planar Surfaces. Part 3. Pattern Effects of Narrow Cracks in the Surface of a Paraboloid Antenna , 1988 .

[12]  Yueh-Chi Chang.  Analysis of reflector antennas with array feeds using multi-point GTD and extended aperture integration/ , 1984 .

[13]  N. G. Van Kampen,et al.  An asymptotic treatment of diffraction problems. II , 1949 .

[14]  L. Peters,et al.  Evaluation of edge-diffracted fields including equivalent currents for the caustic regions , 1969 .

[15]  A. Yaghjian,et al.  Incremental diffraction coefficients for cylinders of arbitrary cross section: application to diffraction from ridges and channels in perfectly conducting surfaces , 1991, Antennas and Propagation Society Symposium 1991 Digest.

[16]  A. Yaghjian,et al.  Low-frequency scattering from two-dimensional perfect conductors , 1992 .

[17]  A. Ludwig.  The definition of cross polarization , 1973 .

[18]  O. M. R. S. L. R. Pres..  XXX. On the light dispersed from fine lines ruled upon reflecting surfaces or transmitted by very narrow slits , 1907 .

[19]  Comparison of three cross-polarisation prediction methods for reflector antennas , 1986 .

[20]  K M Mitzner,et al.  Incremental Length Diffraction Coefficients , 1974 .

[21]  A. D. Yaghjian,et al.  Incremental diffraction coefficients for planar surfaces , 1988 .

[22]  Théodore de Saussure.  LVIII Observations on the change which carbonic acid gas experiences by the electric spark, and on the decomposition of the same gas by hydrogen gas , 1803 .

[23]  E. Knott,et al.  The relationship between Mitzner's ILDC and Michaeli's equivalent currents , 1985 .