1. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris 2-PAD Infrastructure Georgina Harris SKADS System Design and Team Leader

2. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris 2-PAD Overview

3. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris 2-PAD 3 Sets of Antennas / Front Ends for Initial Trial –Vivaldi –Bunny Ear –Cross Logarithmic Sparse Use of CAT7 cabling for data transport to bunker Representative RFI Shielded Bunker Representative Signal Processing Mechanical Supporting Structure representative of that proposed for SKA Upgrade path built in for addition of alternative new technologies such as antennas and data processing technologies

4. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Element Support Grid, Foundations, and Civil Engineering Although the installation in the Cheshire countryside will not be identical to the desert sites, it will enable us to troubleshoot the basic structural design and test the mechanics of assembling the array. It will also allow us to improve the design for easy modular deployment in the desert.

5. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Antennas are mounted on a framework and groundplane and all front end electronics are enclosed underneath these in a thermally insulated space. This allows the temperature of the front end electronics and cables to be stabilised and or cooled.

6. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Polythene Tarpaulin for Water and Weatherproofing Once the array is thermally insulated, the antenna assembly will be waterproofed and protected from the effects of direct sunlight using a white (reflecting) polythene tarpaulin. Desert condition testing will be needed to verify that the combination of insulation, weather protection and temperature control does not lead to problems with –Pests –Material Degradation –Moisture Accumulation Problems

7. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Cable Routing and Support One of the biggest logistical problems will be the deployment of the CAT7 cable because it will be extremely difficult to prepare the terminations on site (either for 2-PAD or the full SKA). 2-PAD will use pre- terminated cables. For the full SKA we envisage pre-bundled cables, cut to the correct lengths that can be fitted to one tile.

8. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Processing Bunker Currently working with a RFI consultancy to develop a custom shielded cable sock. This is to minimise the RFI emitted from the bunker via the cables plugged into the bunker wall. We are intending to use a processing bunker manufactured to the basic pattern of a standard transport container. This also permits the processing bunker to be assembled before it is shipped (i.e. computers in-place).

9. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Processing Bunker

10. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Potential SKA Station Layout

11. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris Conclusions 2-PAD aims to demonstrate the technologies that could be used to produce the phased array. We aim to use this demonstrator as a tool with which we can assess –Signal processing –Front-end designs –Temperature stabilisation / cooling strategies –Manufacturing and assembly techniques

12. Georgina Harris 11 th October 2007 2 nd SKADS Workshop – Observatoire de Paris On-site materials testing should be carried out to verify that the array configuration that the materials we are using in our designs will suffer no unexpected problems once it is in desert conditions.