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Thermal analysis of a SKA AA MID antenna in the desert

Submitter: Hiddo Hanenburg
Description: The mechanical design group of the ASTRON R&D department is designing housings for the AA antennas of the SKA MID frequency range. Since SKA will be located in a desert, the harsh environment has to be taken into account. Computational Fluid Dynamics analysis is performed to determine the influence of the Solar radiation on the temperature of the housing surfaces, and on the electronics inside. The maximum temperature affects the lifetime of these components. At night there is a strong radiative loss of heat to the clear sky. The large diurnal temperature variations have their influence on the electronics. For optimal signal stability and long calibration intervals, the temperature changes over time should be small.

The picture shows a model of a "naked" tile in the Sun, i.e. without any cover, and at the hottest time of the day. The model consists of a ground-plane and simplified vivaldi antennas. The tile is placed on legs on the desert soil. In the analysis, the temperatures and air velocities are calculated over several days and nights in time steps of 6 minutes.

The colors represent the temperatures of the surfaces of the antenna and the ground. The temperature of the legs is not shown, so these are gray. The temperature of the air is 34 degrees C. This is not shown in the picture. The direction and velocity of the air flow is shown as small arrows.

Clearly visible are the hot surface of the soil and the cool shadow below the tile. The cooling effect of the air results in cool antennas, and cools the ground-plane with electronics to 40 C.

The calculation time is about 22 hours and generates a data file of 183 GB.
Copyright: Hiddo Hanenburg
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