Chirp Impulse Radio Ultra-Wideband Antenna Array with Low Sample-rate Digital Beam Steering

In this paper, we propose a novel type of Impulse Radio Ultra-Wideband (IR-UWB) beamforming structure that we named a chirp beamformer. It represents an alternative to the well-known correlation beamforming paradigm. The chirp beamformer uses a chirp pulse as a symbol waveform. In comparison with a correlation beamformer, the chirp beamformer requires considerably lower timing resolution in cases where the IR-UWB symbol consists of a relatively long single uninterrupted waveform, as in the mandatory modes of two of the IEEE 802.15 IR-UWB standards, namely IEEE 802.15.4a-2007 and IEEE 802.15.6-2012. Furthermore, the bandwidth of the signal that the chirp beamformer generates in the baseband is considerably lower than in the case of the correlation beamformer. Hence, in the case of digital baseband signal generation, the chirp beamformer requires a considerably lower sampling rate than the correlation beamformer. A method for shaping the beam pattern of the chirp beamformer is also described. All concepts introduced are illustrated by numerical examples.