Let the receiver is at point $\mathrm{A}$ and source is at $\mathrm{B}$ and the distance between $\mathrm{AO}=\mathrm{OB}=\mathrm{d}$
$$
\mathrm{CA}=\mathrm{CB}=\mathrm{x}
$$


Velocity of waves $=3 \times 10^8 \mathrm{~m} / \mathrm{s}$
Method time to reach a receiver $4.04 \mathrm{~ms}$
$$
=4.04 \times 10^{-3} \mathrm{sec}
$$
So, by echo the height of satellite is given
$$
\left(h_s=600 \mathrm{~km}\right) \text {. }
$$
Radius of earth $=6400 \mathrm{~km}$
Size of transmitting antenna $=\mathrm{h}_{\mathrm{I}}$
We know that,
Distance travelled by wave $=$ velocity of waves Time
or $\frac{2 x}{t}=V$
$$
\frac{2 \mathrm{x}}{4.04 \times 10^{-3}}=3 \times 10^8
$$
or $\quad x=\frac{3 \times 10^8 \times 4.04 \times 10^{-3}}{2}$
$$
=6.06 \times 10^5=606 \mathrm{~km}
$$
Using Phythagoras theorem,
$$
\begin{aligned}
&\mathrm{d}^2=\mathrm{x}^2-\mathrm{h}_{\mathrm{s}}^2=(606)^2-(600)^2=7236 \\
&\mathrm{~d}^2=7236 \mathrm{~km} \\
&\Rightarrow \mathrm{d}=85.06 \mathrm{~km}
\end{aligned}
$$
The distance between source and receiver $=2 \mathrm{~d}$
$$
=2 \times 85.06=170 \mathrm{~km}
$$
For the maximum distance covered by signal from satellite on ground from the transmitter
$$
\mathrm{d}=\sqrt{2 \mathrm{Rh}_{\mathrm{T}}}
$$
or $\quad \frac{d^2}{2 R}=h_T$
or size of antenna $\mathrm{h}_{\mathrm{T}}=\frac{7236}{2 \times 6400} \mathrm{~km}$
$$
=0.565 \mathrm{~km}=565 \mathrm{~m}
$$
We can not obtain signals of $\left(h_T=565 \mathrm{~m}\right)$ at $d=85.06$
$$
\mathrm{km} \text {, So hight or size of required antenna }=566 \mathrm{~m} \text {. }
$$