A.O. Manichev - Ph.D. (Eng.), Deputy Head of Department, JSC "MSDB "Almaz-Antey?. E-mail: alex_manichev@inbox.ru
V.A. Balagurovskij - Head of Special Design Bureau, STC "Altair" JSC "MSDB "Almaz-Antey?

Determination of the parameters of phased array antennas (PAAs) requires a huge number of precise measurements. This, of course, means that modern high-speed instruments should be used. Another way to improve the efficiency of the measurements involves application of digital processing methods of the measured data. A number of practical tasks are considered here. 1. It is convenient to measure the radiation pattern of a PAA without its movement (rotation). This can be achieved through the use of the switching and modulation methods [1, 2]. In order to decrease the negative impact of the inter-element mutual coupling, the additional processing of the measured data should be used [3]. 2. The amplitude and phase characteristics of the PAA elements can also be measured at a high speed with the switching methods. An additional increase of the speed can be obtained via making measurements in the frequency sweep mode [4, 5]. 3. The mutual coupling effects can be studied with the help of the Walsh-Hadamard and Fourier transforms [6, 7]. In the case of non-regular element spacing a good description of these effects can be obtained by the statistical theory of antennas [8, 9]. 4. The lines of the PAA feeding system can be successfully tested through the measurement of the reflection ratio in a frequency range and subsequent digital processing of the measured data with the help of the Fourier transform [10]. In the case of the lines with a frequency dispersion (for example, waveguides), excellent results gives the usage of a special non-linear frequency grid [11]. 5. If the radiation pattern of a PAA is measured at a number of frequencies, the parasitic reflections distorting the measured radiation pattern can be filtered in the time domain region [12]. This filtering implies that the frequency sensitivity of the radiation pattern is rather low. Therefore, in the case of electrically large PAAs, it is desirable to apply a special phase distribution in order to decrease this negative effect [13]. 6. The methods using the digital processing of the measured data can be used for determination of the failed elements and modules in a PAA without elimination of the feeding network [14]. This can be done through the use of the equipment intrinsic to the radar, containing the PAA [15]. In the case when the access to the PAA under test is inconvenient, the diagnostics of the PAA elements without auxiliary antenna is of great interest. Such a method is based on the measurement of the signals reflected from junctions radiators-free-space [16-19]. Thus, the efficiency of the PAA parameters measurement in a number of practically important cases can be significantly improved through the use of digital processing methods of the measured data. In some cases these methods give the only practically viable possibility to get the required information.