4.9 (data and computer communication) 4.9. You are communicating between two sat

Question

4.9 (data and computer communication)

4.9. You are communicating between two satellites. The transmission obeys the free space law. The signal is too weak. Your vendor offers you two options. The vendor can use a higher frequency that is twice the current frequency or can double the effective area of both of the antennas. Which will offer you more received power or will both offer the same improvement, all other factors remaining equal? How much improvement in the received power do you obtain from the best option?

Explanation / Answer

Answer for given Qusestion:

If the link obeys the free space law, we know that the power received is:

Pr = (Pt*Gt*Ar)/4*pi*R^2

Now we can relate gain of the transmit antenna to it effective area by:

Gt = (4*pi*At)/Lambda^2

Using the above equation in the Pr expression we can express the power received in terms of wavelength ( frequency) and antenna area:

Pr = (Pt*At*Ar)/(R^2*Lambda^2)

Now we can easily see what effect on power received for the two cases mentioned.

Case 1: Double At and Ar

Case 2: Double the frequency, which reduces the wavelength by 1/2

Compute Pr for both case and you can see which one is the better change, and what the effect on received power is.

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