Sunday 3 July 2011

Power poles

The main power line to the KAIRA site has now been completed and has been energised. This brings the mains across to the south edge of the HBA field. It is done using tall timber poles to avoid too much disruption to the native ground cover and to make maintenance and deployment easier.

At this point there is the final power pole, and a connection down to a termination box. From there the cable needs to go underground for the rest of the way to the central site power point (which is located in the RF-container). The underground cable has been buried in, but it has not yet been connected, as the termination at the RF-container end has not yet been installed.

Because of the sensitivity of the array, it is essential that the electrical power line be kept out of the way on the final approach to the site. This is not just because it carries power, but because it is a long metal object. This reflects radio waves, which can cause confusion in the final images.

The same applies to other metal objects. They have to be kept away from the array as much as possible to minimise these reflections.

Even the reflections of astronomical radio sources (such as Cas A, Cyg A, etc.) can cause spurious images ('ghosting') to appear in the data.

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