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A satellite in geostationary orbit is used to transmit data via electromagnetic radiation. The satellite is at a height of 35,000 km above the surface of the earth, and we assume it has an isotropic power output of 1 kW (although, in practice, satellite antennas transmit signals that are less powerful but more directional).Imagine that the satellite described in the problem introduction is used to transmit television signals. You have a satellite TV reciever consisting of a circular dish of radius R which focuses the electromagnetic energy incident from the satellite onto a receiver which has a surface area of 5 cm^2.How large does the radius R of the dish have to be to achieve an electric field vector amplitude of 0.1 mV/m at the receiver?

Respuesta :

Answer:

Explanation:

We have the following relation between power, P and intensity, I

[tex] I = P/(4*pi*r^2) [/tex]

= [tex] 10^3/(4*pi*(35000*10^3)) [/tex]

= [tex] 6.5*10^-14 W/M^2 [/tex]

We also have the following relationship between electric field and electromagnetic radiation thus

[tex]  I = (ceE^2)/2 [/tex]

Hence [tex] E = \sqrt{2I/ce} [/tex]

substituting the values of I, c and e, we have

[tex] 7*10^-6 V/m [/tex]

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