Radiation Patterns of Arrays on a Reflecting Cylinder

Simple approximate formulas are derived for the horizontal and vertical patterns of directional arrays of dipoles arranged on an arc of a circle or on the surface of a right circular cylindrical segment and backed by a reflecting cylinder. The dipoles may be aligned axially or circumferentially and the amplitude distribution on them may be uniform or cosinusoidal. The results are valid in the vicinity of the radiation maximum, but are less certain at wide angles unless the dipole spacing is substantially less than a half wavelength. It is found that the array patterns compare favorably with those of linear arrays of comparable dimensions and similar amplitude distributions, and that there exists, in certain cases, an increase in gain over the linear array brought about by the end-fire effect inherent in the geometry of the circle.