1. Netherlands Institute for Radio Astronomy AA MID technical progress meeting Environmental prototypes and thermal models Marco Drost Hiddo Hanenburg 1 ASTRON is part of the Netherlands Organisation for Scientific Research (NWO)

2. 2 Content presentation Environmental prototypes  Purpose  Fuzzy design drivers  Prototypes Thermal modelling  Purpose  Passive cooling  Thermal model

3.  Dust collection  Soil variations, erosion due to wind and water  Vegetation, maintenance  Bugs  Rodents  Large wildlife and birds  Water transport, flow over ground, puddles en floods  etc 3 Environmental prototypes Fuzzy design drivers It is possible to indentify environmental design drivers but in many cases it is not possible to predict the frequency of occurance and effect they will have on the system. Some examples:

4. Environmental prototypes Prototypes 4 Open prototype Closed prototype Insulated prototype Each prototype should have the following features: Antenna (ground plane) not functional Electronics not functional Dissipation between 50 to 100 W/m2 Most sensitive component or circuit RF shielding Connectors Conformal coatings and no coating Cabling inside tile as also outside tile In the soil On top of soil Antenna en cable connection between tiles and stations

5. Thermal modelling 5 Passive cooling Thermal modelling

6. Thermal prototypes passive cooling 6

7. Thermal modelling Emissivity and absorbtion factor 7

8. Thermal modelling Dynamic behavior ground soil 8 Material Density ρ kg/m³ Thermal Conductivity k W/m*K Specific Heat c p J/kg*K Solar Absorptivity α s Emissivity ε Clay, dry15500.930 Clay, wet14951.675 Sand15150.2 - 1.08000.9 Sand, dry, Off-white0.520.82 Sand, dry, Dull red0.730.86 Soil, dry15001.01900 0.93 - 0.96 Soil,wet19002.02200

9. Thermal modelling Transient matlab model 9

10. Thermal modelling Transient model 10

11. Thermal modelling FEM transient modelling 11

12. Questions 12  Questions