3D space-time digital filtering for radio astronomy




Liyanage, Najith

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The development of large dense arrays of smaller antennas and moderate-sized antennas equipped with multi-beam arrays in the next generation of radio telescopes, such as the square kilometre array (SKA), is making 3D space-time (ST) filtering increasingly relevant for applications in radio astronomy. The next generation of radio telescopes, such as the SKA, are expected to achieve unprecedented levels of sensitivity, resolution, survey speed and field of view (FOV). In this regard, the mitigation of radio frequency interference (RFI) and the suppression of mutually coupled (MC) signals on dense antenna arrays are being identified as most challenging. The main contribution of the work presented in this thesis is the proposal of a 3D ST filtering approach to enhance signals of interest (SOIs) by attenuating over-the-horizon RFIs and MC signals that exist on dense phased arrays. For this purpose, a novel 3D linear phase filter bank structure consisting of I D FIR filters and 2D circularly symmetric FIR filters is proposed. The advantage of the proposed ST filtering approach is its inherent capability of broadband (BB) processing. The proposed 3D ST filtering approach is investigated on synthesised BB SOI, BB RFI and BB MC signals on dense aperture arrays (AAs) and focal plane arrays (FPAs). The results indicate successful mitigation of over-the-horizon BB RFIs and moderate suppression of BB MC signals, without significantly distorting the BB SOIs.



Arrays, Antennas, Filters