The array antenna consisting of rectangle form subarrays (modules) is considered. Modules are placed in space in two ways: on the plane and on the lateral surface of a cylinder, forming a multi-faceted array antenna. The effect of number of array’s defective  radiating elements (individual radiators or modules) on antenna pattern parameters and antenna directivity is investigated. Three forms of flat array’s aperture are considered: rectangle, elliptical and octagonal. The numerical simulation is used for analysis. Defective radiating element is referred to as that one, which has zero excitation amplitude. Defective elements are placed on the antenna’s surface randomly.