Electromagnetic waves emitted by an omnidirectional broadcast antenna on Earth strike a 4.23-m^2 flat surface that forms part of an artificial satellite that is located 251 km from the antenna. The surface is oriented perpendicular to the propagation direction of the waves and acts as a perfect reflector. What power output in gigawatts would be required from the antenna in order to acheive a radiation force of 1.87N on the surface?

P = 0.42 GW

Explanation:

For this in exercise let's calculate the intensity of radiation on the antenna, for this we use the expression of the radiation pressure on a reflective surface

P = 2 I / c

The definition of pressure is

P = F / A

F / A = 2 I / c

I = F c / 2 A

Let's calculate

I = 1.87 3 10⁸ / (2 4.23)

I = 0.993 10⁸ W / m²

This is the intensity over the satellite antenna

The definition of intensity

I = P / A

The emitted power is

P = I A

P = 0.993 10⁸ 4.23

P = 4.2 10⁸ W

P = 0.42 GW