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The Square Kilometre Array is a next-generation radio telescope originally slated to operate at 70 – 450 MHz frequency in its lowest band (SKA-low). This thesis examines aspects of SKA-low station design and finds that two-stage beamforming produces acceptable performance. Additionally, single- and dual-polarised conical spirals are evaluated as candidate SKA-low elements. Though neither versions are strong candidates for SKA, the single-polarised spiral is an excellent antenna for use in Global Epoch of Reionisation experiments.

The lowest frequency band (70–450 MHz) of the Square Kilometre Array (SKA) will consist of sparse aperture arrays grouped into geographically localised patches or stations. Signals from thousands of antennas in each station will be beamformed to produce station beams which form the inputs for the central correlator. Two-stage beamforming within stations can reduce SKA-low signal processing load and costs, but has not been previously explored for the irregular station layouts now favoured in radio astronomy arrays. This paper illustrates the effects of two-stage beamforming on sidelobes and effective area, for two representative station layouts (regular and irregular gridded tiles on an irregular station). The performance is compared with a single-stage, irregular station. The inner sidelobe levels do not change significantly between layouts, but the more distant sidelobes are affected by the tile layouts; regular tile creates diffuse, but regular, grating lobes. With very sparse arrays, the station effective area is similar between layouts. At lower frequencies, the regular tile significantly reduces effective area, hence sensitivity. The effective area is highest for a two-stage irregular station, but it requires a larger station extent than the other two layouts. Although there are cost benefits for stations with two-stage beamforming, we conclude that more accurate station modelling and SKA-low configuration specifications are required before design finalisation.

The SKA is a next generation radio telescope employing phased aperture arrays at its lowest operating band (SKA-low) of 70 - 450 MHz. SKA-low is a dual-polarized array consisting of antenna elements with stable impedance and low cross-polarization. We select the well-known broadband conical spiral antenna and its dual-polarized derivative to be evaluated as candidate elements for SKA-low. Previously, we evaluated the sheet version of the conical spiral and found that it maintained well its broadband characteristics. Looking towards ease of manufacturing, we now evaluate wire versions of the designs. We find that the single-polarized wire version has stable impedance and low cross-polarization from 150 - 450 MHz. However, at low frequencies the cross polarization increases. The dual-polarized version maintains its characteristics over a small band but with higher (> -20 dB) cross polarizations. Measured results confirm the simulated antenna behavior.

Aperture Arrays (AA) mark a new era in radio astronomy combining high sensitivity with a large field-of-view, enabling very high survey and imaging speeds. This paper describes the development of low frequency aperture arrays leading up to SKA phase 1 within the Aperture Array Verification Program (AAVP) as part of the SKA program.