Analysis and modeling of thermal effects on the parabolic reflector antenna performance.

Yasamin Fawzi Aziz
Dr. Asaad Mubdier Al-Hindawi
Dr. Abaas Al-Shalchi

Abstract: Large antennas, such as required for radio astronomy or interplanetary probes, or ground stations of satellites, are engineering structures subject to gravity, wind, and thermal strains. The conditions especially the temperature gradient can cause undesired shape deformation, twists, and strain concentration in the structure, which can adversely affect the performance of antenna systems for both pointing and accuracy. In this thesis the thermal effects on the electrical characteristics of the reflector parabolic antenna are studied. The expression of the reflector surface error occurring due to temperature changes were calculated by modeling the reflector surface by using ANSYS program and using Matlab programs for simulation. The expressions of the antenna gain and radiation pattern due to above reflector surface errors are also determined. Based on thermal sensors fixed on different points on the reflector surface, the data of temperature distribution for the antenna surface were recorded, and practically measured in both seasons winter and summer, for different antenna elevation angles (34°,40°,60°,80°)and for different antenna material colors (gray, black and white color). Then the antenna parameters (gain, radiation pattern, directivity, efficiency etc….) are calculated