This month’s media comes from Associate Professor Randall Wayth from our Curtin University node, with the results of an exciting internship project by Mr Uli Kiefner. The image is an overlay of the Engineering Development Array #2 (EDA2) photographed from a drone with the results from a holographic measurement of the EDA2 array aperture.
The EDA2 is a single station prototype system for the future Square Kilometre Array LOW (SKA-low) radio telescope, using the same dipole antennas as from the Murchison Widefield Array (MWA). The project aims to address outstanding questions regarding the station calibration and inter-element mutual coupling that arose from the SKA-low critical design review in 2018 (in other words, how does it all work together?). Along with the EDA2, another prototype station – the Aperture Array Verification System 2 (AAVS2) – was built in 2019 to investigate the detailed properties and performance of different antenna designs. The overlaid image is a direct independent measurement of the electric field response of the antennas in the array, made via a new holographic technique that forms part of Uli’s project. The “hot spots” in the overlay match exactly the known locations of the antennas.
A drone photo of the Engineering Development Array #2 overlaid on the left by the holographic measurement of the EDA2 array aperture.
The relative locations of antenna in an interferometer or aperture array (a group of antennas acting as one), such as the SKA-low or MWA, can affect what the telescope can see in the sky. Simplifying it to only two antenna, the wider they are apart the smaller the details that can be seen, but the larger details get lost. The same is true in reverse, where the closer the antennas are together the better larger details can be seen but the smaller details are lost. Closely spaced antennas can also interact with each other electromagnetically, which changes their performance. Understanding what effect of the proposed SKA-low layout and antenna choice will have on observations will allow us to better understand exactly what the SKA-low telescope will be best suited to study, and assist with the final planning of the interferometer. It will also make calibrating the SKA-low telescopes easier.
