Wednesday 29 June 2011

HBA configuration

KAIRA is made up of two arrays... the Low-Band Array (LBA) covers the frequency ranges 30-80 MHz and the High-Band Array (HBA) spans from 120-240 MHz. Firstly, I should start off by pointing out that only the HBA is being built this year. Because the summer is so short in the Arctic, we simply do not have time to get the LBA constructed as well... especially with the added complication of difficult terrain! Instead, we're concentrating on getting the HBA done.

You may recall a long time back, we ran a couple articles (Part-1, Part-2) on the configuration of the High-Band Array. That was before the details calculation of beam patterns, site area planning and the destructive testing after the winter trial period. As we said, the array layout might get revised to adapt to our improved understanding of the array geometry options.

Well, here is the final decided layout.

The actual KAIRA deployment is shown in the darker grey. The faint grey outlines show the location of a LOFAR international station. As we mentioned, we would like to expand the array in the future to have a 'full' international HBA, in addition to the LBA which is already scheduled. This means that our HBA deployment must be made to the same 'grid' as the international layout.

Also shown on the diagram are the tile antenna identifiers (H22, H23, etc.). Again, the scheme used is consistent with the 'international upgrade' idea.

The layout is split into three 'blocks' of 6×4, 6×2, 6×2. By splitting the array into a semi-sparse configuration, it will allow us to try different sub-array combinations for EISCAT_3D. The 'corridors' between them will also be used for snow clearing.

Although winter tests have been carried out, we are still being conservative with our snow strategy and wish to ensure that we have a way of clearing the snow for winter observations.

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