Table of Contents
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Low Noise Amplifier (LNA)
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The radiometer is connected to a feed which illuminates a 10 foot diameter dish with f/D ratio of 0.4. The feed is made by adding a l/4 probe to the C-band (4.2 GHz) feed. The outer diameter of the C-band (4.2 GHz) feed. The outer diameter of the C-band feed is about 8" which supports a TE11 circular waveguide mode with a/l » 0.5 which is close to optimum for a f/D » 0.4 [see Methods of Experiment Physics, Astrophysics edited by Marton, vol. 12B page 32.] The aperture efficiency should be close to 60% (or 50% when the feed and feed support blockage is taken into account.) so that
-TA = (FAη/2k) × 10-2026
where A = area of the reflector
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