Electromagnetic Gap Leakage Analysis for the SKA Mid-Frequency Dish

This paper presents electromagnetic analysis as performed on the Square Kilometre Array (SKA) mid-frequency dish in order to estimate the ground leakage caused by gaps in the main reflector. The effects of the ground leakage are shown in terms of conventional performance parameters such as gain and aperture efficiency, as well as the percentage of feed power hitting the ground behind the main reflector. Analysis were performed for SKA Band 1 and 2 with a combined frequency range of 0.4 − 1.8 GHz. It is shown that the gaps in the main reflector reduce the gain between 0.23 and 0.05 dB and could increase the noise temperature by approximately 14 K when pointed at zenith. The transmission percentage of the incident power hitting the ground is below 0.2% across the combined bands.