Tuesday 19 October 2010

Deploying the test tiles

Today the two test tiles were placed on the site. A snow-plough lorry with a loader crane was used to lift the tiles into position. For the tile that was put directly onto the ground, this was moderately straightforward. However, the raised frames made things somewhat more tricky.

Once the tiles were in place, the lids and covers could be applied. We'll no doubt explain this in more detail when we write about the actual placement of the final antennas. But for now, it will suffice to say that this means applying covers and securing the tiles to the ground.

As it turned out, we were just in time. As the second tile was placed and we started the covering and securing, the snow started to fall. Within 10 minutes, there was already a reasonable dusting of snow over the tiles, tools and equipment.

In the foreground of this image, the low tile can be seen while in the background the raised tile is still being secured.

With the work done, it was time to clear up. Safety markers were put up around the area and signs were erected to explain what on earth these strange things are!

The signs explain that these are antennas under test. They are written in four languages: Sami, Bokmål, Finnish and English.

Monday 18 October 2010

Preparation work

The idea was to deploy the tiles before the first winter snows arrived. And although there was some scattered patches of snow on the ground when the team arrived, it certainly wasn't anything prohibitive.

The first step for placing the two test tiles was to level the patches of ground where the tiles would go. This was done with the help of a laser level (see here glaring into the camera lens).

Once the two areas were level, the frames could be assembled on the northern patch. As explained in an earlier post, we intend to put out two tiles. One will go on a raised platform made of open timbre frames, and the other will go directly to the ground (like in conventional LOFAR stations).

Once the frames were put in place, we took delivery of the tiles themselves. These arrived on an articulated lorry and were unloaded in the afternoon.

When packed, the tiles are stood vertically, folded over. At 5 metres long, and 2.5 metres high, they are actually quite vulnerable in this position. As a result, we quickly assembled a support frame that would secure them overnight, ready for tomorrow's deployment.

Sunday 17 October 2010

Frames to go!

In order to limit the amount of drift snow that banks up on or against the antennas, the KAIRA project plans to put the high-frequency tiles on a raised platform, made from a series of frames. By raising the tiles, they will be subjected to greater wind speeds and will avoid the immediate ground boundary layer.

To test this, and various other concepts, two test tiles will be deployed at the site this year. They will be monitored over the winter and fully inspected in the spring. Of the two tiles, one will be placed on a 1-metre high platform and the other directly to the ground (like is done at conventional LOFAR sites).

The deployment of these test tiles will be carried out over the next couple of days. And, although the tiles themselves will be delivered directly to the site, the frames will be taken up from the institute.

In this photograph, the set of timber frames has just been loaded onto the trailer, ready to be towed up to the site.

Wednesday 8 September 2010

Surveying the field

The top priority task is to conduct an initial survey of the proposed deployment area. This was carried out today at the site using a simple theodolite, tape and survey stick... backed up with a GPS receiver! During the survey, a number of set positions were used. This photograph shows the theodolite set up at the primary position.

During the surveying work a number of reindeer passed by to see what we were doing!

Looking across the theodolite, there is a nice view of the area where the low-frequency array could possibly be deployed. One of the survey team can be seen holding the 5-metre survey stick.

Test site at Kilpisjärvi

Although we are confident that the antennas will resist the harsh Arctic conditions, it is necessary to conduct some 'winter tests' with real hardware, in order to prove our assessment. Therefore, on the proposed site, we will deploy two 'test tiles'. These will be left over the winter and occasional checks will be made to evaluate their condition.

However, before the tiles can be deployed, it is necessary to survey the proposed area. Here are a few photographs of the site. In the first, the rocky area in the foreground is where the array is likely to be deployed.

In the next image, there is another view across the site. And, of course, there is another glimpse of some of the spectacular surrounding scenery.

Monday 5 July 2010

Two types of antennas

The KAIRA project will make use of proven LOFAR antenna designs. LOFAR is the Low Frequency Array — a pan-European radio telescope project that is currently under construction.

There are two main types of LOFAR antennas. These are the so-called 'low-band' and 'high-band' antennas. The low-band antennas are aerials, covering the range 30 to 80 MHz. Each one stands approximately 1.8m tall, and has a 3 × 3-metre base. The high-band antennas are tiles and are designed to operate in the range 120 to 240 MHz. These tiles are only 0.5 metres tall, but have a larger 5 × 5-metre footprint.

Wednesday 30 June 2010

Kilpisjärvi Atmospheric Imaging Receiver Array

Welcome to KAIRA! This is the weblog of the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA). This is a project of the Sodankylä Geophysical Observatory, principally funded by the University of Oulu in Finland. KAIRA is a dual array of omni-directional VHF radio antennas. It makes extensive use of the proven LOFAR antenna and digital signal-processing hardware, and can act as either a stand-alone passive receiver, as a radar receiver for the VHF transmitter in Tromsø, or for use in conjunction with other Fenno-Scandinavian VHF experiments. It will be used for engineering experiments as well as conducting scientific observations of atmospheric and astrophysical phenomena. In additional to being a powerful observing instrument in its own right, KAIRA will act as a pathfinder for technologies to be used in the proposed EISCAT-3D system.