Polar patterns of phase-corrected circular arrays

The paper considers the polar response of an array of similar radiators placed uniformly around a circle, in which each radiator is phase-corrected to bring the radiation from all radiating elements into common phase in one direction. Such an array tends to have a pattern with undesirably large side lobes. The effects of varying (a) the polar response of the individual elements, (b) the relative weighting of the elements and (c) the element spacing, are examined. It is found that the side-lobe level can be greatly reduced if (a) each element has a polar pattern confined mainly to the forward hemisphere, with, in particular, a null at 90°, (b) only elements within ±90° of the main beam are used, and (c) the spacing between elements is not more than half the wavelength.