Measuring Far-Field Radiation Patterns of Digital Beamforming Antenna Arrays

A method of the antenna array far-field Radiation Pattern (RP) measurement is considered. This method is designed for the usage with the receiving Digital Beamforming Antenna Arrays (DBAA). Such type of antenna arrays typically does not have a radiofrequency output. Hence, the standard methods of the RP measurement, based on the radiation and the reception of the monochromatic probing signal, cannot be used for the DBAA RP measurement. The proposed method assumes the radiation of a probing signal modulated by a pseudo-noise sequence and the base-band processing of the DBAA output signal by means of a matched filter or a correlator. The paper presents the description of the measurement setup and the mathematical explanation of the measuring procedure. It has been shown that the accuracy of the RP measurement depends on the Signal-to-Noise Ratio (SNR) at the outputs of the DBAA channel receivers, the number of the array channels and the number of the pseudo-noise sequence symbols. The accuracy increases on 3 dB each time as the number of the array antennas or the pseudo-noise sequence symbols is doubled. This result is confirmed by the simulation of the RP measurement of the eight and the sixteen channel linear antenna arrays with the usage of the maximum length pseudo-noise sequence of 1023 and 2047 symbols.