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How is Antenna Efficiency Defined and How Can One Use Measurements of the Sun to Calculate It?

-- | May 16, 2018

Question: I am an undergraduate Physics student carry out a research to determine the brightness temperature of the sun at 4 GHz and 12 GHz with offset dishes and prime focus dishes and would like to find out how can one determine the efficiency of a parabolic dish like a C band dish and offset dish like a Ku band dish (dstv dish). other articles mention that the efficiency of a dish lies between 0.6-0.75. Is there a mathematical formula for calculating the efficiency accurately for the individual dishes. the second question is does the sun emit non thermal or thermal radiation at 4 GHz and 12 GHz. if so what are the corresponding brightness temperature at that frequency. is there reference information about brightness temperature of the sun at those specified frequencies that i can refer to when doing my research. Your response will be highly appreciated. — Mukadi

Answer: For information on how radio telescope antenna efficiencies are calculated, let me point you to a resource page which provides a number of Radio Astronomy Tutorials, one of which is a tutorial on Temperature Scales and Telescope Efficiencies. For information on the brightness temperature of the Sun at 4 to 12 GHz, there are quite a few references. A relatively recent reference, which also includes some other useful background information on the properties of the radio emission from the Sun, can be found in a Jet Propulsion Laboratory research report from 2008. I think that with the tutorial and solar emission flux information you should be able to measure your antenna efficiencies.

Jeff Mangum

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