Question

# A space mission is launched and the spacecraft has been sent with a half-wave dipole antenna...

A space mission is launched and the spacecraft has been sent with a half-wave dipole antenna operating at a frequency f. The ground station has an identical antenna to communicate to the spacecraft. After a period of time it is noticed that communication from the space craft is lost when it is at a certain distance, R, from the ground based antenna. As a solution to this, the ground station antenna is replaced with an antenna of 120dB gain, transmitting the same amount of power. Calculate the distance, D at which communication from the space craft will be lost again? Assume both antennas are ideal.

Given data :

Ground station antenna is replaced by antenna of 12p dB gain.

We know that Intensity of a signal is the ratio of power and area as,

When we measure in decibal, then

where

I = Intensity at a distance D

= Intensity at a distance R

We know that, 120 dB gaingain antenna is installed then, putting in above data we can say that

so

So

Note that , Log is on base 10, so

So

the distance, D at which communication from the space craft will be lost again is

Thanks

Have a nice day

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