How are parabolic satellite dishes used to focus signals?

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Diagram showing a double cone intersected by planes at different angles, producing the conic sections: a horizontal plane creates a circle, a tilted plane creates an ellipse, a plane parallel to the cone's side forms a parabola, and a steep plane produces a hyperbola. Each section is labeled, with the axis and apex of the cone indicated. — analytic geometry The conic sections result from intersecting a plane with a double cone, as shown in the figure. There are three distinct families of conic sections: the ellipse (including the circle), the parabola (with one branch), and the hyperbola (with two branches).

Parabolic satellite dishes function by utilizing the geometric properties of a paraboloid. Because of their concave shape, these dishes are designed to collect incoming signals—such as microwaves—from a distant source and reflect them toward a single point known as the geometrical focus.1

By positioning a receiver at this focal point, the dish effectively concentrates the incoming waves, allowing for the capture and processing of signals that would otherwise be too weak to detect. This same principle is applied in reverse for transmission, where waves emanating from the focus are reflected off the surface to become parallel beams, enabling highly directional communication.1