Satellite Dishes
Geometry & Trigonometry
Fit a parabola to a real satellite dish's profile and check whether the receiver sits at the predicted focus.
Where this idea comes from
Start here — this is the source that inspired this exploration.
Introduction
A parabolic satellite dish reflects every incoming signal, no matter where it hits the dish, to a single focal point where the receiver sits. The largest single-dish radio telescope in the world is the Five-hundred-meter Aperture Spherical Telescope (FAST) in China, and the largest fully steerable dish is the 100 m Green Bank Telescope in the US. This exploration asks you to measure a real dish's profile, fit a parabola to it, and check whether the receiver actually sits at the predicted focus.
Guiding Questions
- Why does a satellite dish reflect every incoming signal to one point?
- Measure a real dish and fit a parabola (or paraboloid) to its profile. Where should the receiver sit?
- Check the prediction against where the receiver arm actually is.
- Offset dishes look asymmetric. How does the geometry still work? Model one.