The Square Kilometre Array (SKA) is an international radio astronomy project with the object of scanning the cosmos from 50 Mhz to 15.4 GHz.
This project was originally conceived in 1991. The first 10 years were about developing the concepts and ideas. The second 10 was spent doing the technology development. And then the last decade was about detailed design, securing the sites, getting governments to agree to set up a treaty organisation (SKAO) and provide the funds to start.
There are two key sites. The SKA-mid array in South Africa covers 350 MHz to 15.4 GHz and it uses dish antennas. In this post, I'll focus on the SKA-low array in Western Australia which covers 50 MHz to 350 MHz.
The SKA-low array will be located at a remote site near Murchison in Western Australia. Bulldozers are expected to start working on the site in early 2023, with the completion date estimated as 2028.
The array is described as follows... "a phased array of simple dipole antennas to cover the frequency range from 50 to 350 MHz. These will be grouped in 40 m diameter stations each containing 256 vertically oriented dual-polarisation dipole elements.".
"Stations will be arranged with 75% located within a 2 km diameter core and the remaining stations situated on three spiral arms, extending out to a radius of 50 km."
While the array description is of 'simple dipole antennas', the 'Christmas Tree' antenna is actually a log-periodic antenna with two polarisation feeds. There seems to be a metallic grid underneath to maximise the gain upwards.
While the gain of each individual antenna is low... possibly in the region of 6dBd... it's the sheer number of antennas fed in phase with each other that gives the high gain and resolution.
The array will produce up to ~5 Tb/s (or ~ 700 GB/s) of measurement data, which is equivalent to downloading ~200 High-Definition movies in one second. This data will be transported via a dedicated fibre from the Murchison Radio-astronomy Observatory to the SKA-Low science processing centre located in Perth.
As might be expected, all radio transmitters are banned from the area to maintain a low noise environment. The Murchison site is about 600kms to the north of the city of Perth and is very remote.
Videos... Sirio are probably better known to the radio community as the manufacturer of various types of CB antenna as well as some for the VHF amateur bands. Their antenna plant in Volta Mantovana (Italy) will produce 78,000 'Christmas tree' antennas which will go to Western Australia to form the low-frequency part of the SKA telescope.
1) The video is in Italian but YouTube does a good job of translating it...
2) This second video titled 'Making the SKA telescopes a reality: the next chapter' gives an overview of the SKA project.
It is expected that the Square Kilometre Array project will contribute to many areas of radio astronomy.
Signals emitted in the first few hundred million years after the Big Bang.
Trace the full history of hydrogen, the most abundant element in the Universe.
Detect hydrogen's presence even before great clouds of it collapsed to form the first stars.
Fast radio bursts which output the equivalent of an entire year's worth of energy from our Sun in just a fraction of a second.
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