D. B. Ostrovskiy

Radar and sonar arrays consist of hundreds and thousands of elementary channels. Active area of an array can be divided into groups or sections. Sections can be grouped, forming a multitier system. In the first tier there are elements directly contacting to medium of distribution, as well as circuits of signal formation or preprocessing. Other tiers consist only of electro-, radio elements or/and digital computing units. In the article influence of random errors (amplitude, phase, placing errors) and failures of elementary channels and sections as a whole on the resultant directivity pattern (DP) of two-tier phased array is considered. It is supposed, that elementary channels and sections are statistically indiscernible, errors have symmetric distribution functions, errors of various types and failures are independent. Analytical expressions for distribution parameters, mathematical expectation and variance of the DP modulus depending on variance of errors and probability of non-failure operation of elementary channels and sections as a whole are presented. When defining statistical characteristics of the main maximum size and side lobes it is suggested to use various factors of standardization. It is shown, that in case of the sectioned array prevailing influence on DP distortion is rendered by sections errors and failures. The solution of an «inverse» problem of the statistical theory of arrays, which consists of definition of requirements to parameter spread, admissible failures of elementary channels and sections and also to minimum admissible quantity of sections, is resulted.