P.A. Shmachilin

Evolution of modern element base of digital schematic allows to talk about the creation of digital active array antennas for microwave signal with the conversion to digital form directly to the carrier frequency in the aperture of the antenna array without necessity of preliminary convert the frequency. This method allows to carry out procedures beamforming and signal processing entirely in the digital domain using digital signal processors and digital signal processing methods. This approach allows to exclude a significant fraction losses of microwave energy in an analog phase shifters and signal distribution system. The transition from converting analog to digital in the microwave region increases the demands on the parameters and characteristics of digital components. The process of conversion signals from analog to digital representation may be regarded as linear but in general a nonlinear voltage-code characteristics of the ADC needs to consider the effect of the noise at the input of the digital part on the directional characteristics of digital antenna array. The article considers some phase errors occurring in consequence of the transition from analog signal to its digital representation in the digital antenna array: phase discretization error that occurs in consequence of the discrete-time digital system; phase quantization error, which arises in consequence of features of representations of real numbers in a digital systems; phase error of jitter, which appears in connection with the fluctuations of the phase characteristics of the synchronization system, the phase error caused by the presence of noise in the input analog signal. In accordance with a common theory of antenna systems, the total phase error digital signal conversion in digital active phased antenna arrays will reduce the properties of the directional antenna array compared to the ideal antenna system.