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Can Radio Waves be Focused Like Visible Light?

-- | February 14, 2016

Question: A visit to your Very Large Array prompted the question, “Can we focus radio waves much as we can focus visible light and lasers?” The question is important if aliens try to send us a radio message. If their transmission attenuates as a cube of their distance, as do regular radio station transmitting antennas, they would need tremendous power to reach us compared to a focused transmission. — Peter

Answer: Yes, radio waves can be focused just like visible light, and all wavelengths of electromagnetic radiation. Also, as you say, the strength of electromagnetic signals decreases as the square of the distance. We overcome this decrease in the signal strength by building telescopes like the VLA with lots of large antennas that can collect a lot of these weak signals.

Jeff Mangum

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