Broadband fractal elements phased array antennas for SKA

Abstract

This thesis presents instrumentations to measure the abundance of neutral hydrogen gas in the Universe. Particularly, instrumentations for 21-cm intensity mapping telescope. The data acquisition of the Universe's hydrogen measurements enable tracking on how its distribution evolves with time. In correspondence, a comprehensive picture on how galaxies evolve: the nature of dark energy: and how the first cosmic structures formed can be drawn. In these terms and the context of SKA, the work employs phased array technologies functioning at the sub 1 GHz frequency band. The mapping instruments rely on an interferometric aperture arrays telescope subdivided into two bands. Aperture array antennas for the SKA covering the low frequency band at the sub 450 MHz and the high-frequency band (300 MHz to 1 GHz) arrays. A novel class of planar antennas referred to as tightly couple phased arrays (TCPAs) are proposed for SKA. This class of antennas enable a wideband performance utilising the mutual capacitance between the array elements. The requirements of a wide bandwidth performance promoted a key innovation, employing a resistive loading layer. Using this novel technique has translated as an improvement in the bandwidth to a factor of two, while the array when conjugated with a superstrate layer mitigates radiation efficiency degradation. These antenna designs are targeting for low-cost and high sensitivity characteristics. The arrays were devised and validated through measurements of their prototypes.