The E-plane radiation patterns of wide-flare corrugated conical and E-plane sectoral horns (2αo< 150°) excited in the dominant mode are obtained employing the theory of Kouyoumjian and Pathak  and the slope diffraction technique . Besides the other parameters of the horn, the finite thickness of the corrugated edge has been taken into account with a view to improve the accuracy of the pattern computation. The analysis presented enables one to predict accurately radiation patterns over the main beam, near and far sidelobes, and the back lobes of the horns. Validity of the analysis is established by satisfactory agreement between the calculated and measured E-plane patterns of a few typical experimental wide-flare corrugated conical and E-plane sectoral horns. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.