The paper shows that the use of the developed communication systems made it possible to completely eliminate unpredictable interference and various interference during the transmission of a microwave signal through it, the accounting of which and their further compensation (for example, by subtraction) requires additional numerous measurements. Changes in the registered radiation pattern of single elements of an active phased antenna array are now only associated with a change in the parameters of the microwave signal emitted by the antenna. This made it possible to develop a new method for determining both defects in an active phased antenna array and defects associated with individual transceiver emitters, based on an asymmetric shift of the maximum of the radiation pattern of the emitter with a defect relative to others, as well as a change in the shape of the diagram itself (for example, a decrease in the amplitude of the maximum and etc.). The obtained research results confirmed the feasibility of using communication systems and the validity of the methodology for determining defects in an active phased antenna array.