What is Receiver G/T in Satellite Communication? | Explained by equations

The ratio of gain of receiver antenna to system noise temperature is called receiver G/T.

Carrier power $$C$$ is given by:

$C = P_r = \frac{P_tG_tG_r}{(4\pi d/\lambda)^2}$

where $$P_t$$ denotes output power of transmitting antenna, $$P_r$$ denotes the power at the receiving antenna, $$G_t$$ denotes the gain of transmitting antenna, and $$G_r$$ denotes the gain of receiving antenna.

Note that only free space path loss is considered here ($$\lambda$$ is wavelength and $$d$$ is the distance between the antennas).

Noise power $$N$$ is described as:

$N = kT_sB$

where $$k$$ is Boltzman constant, $$T_s$$ is system noise temperature, and $$B$$ is bandwidth.

Thus, carrier-to-noise ratio can be obtained:

$\frac{C}{N} = \frac{P_tG_tG_r}{kT_sB}\left(\frac{\lambda}{4\pi d}\right)^2$

This equation can be rewritten as:

$\frac{C}{N} = \frac{P_tG_t}{kB}\left(\frac{\lambda}{4\pi d}\right)^2\left(\frac{G_r}{T_s}\right)$

It turns out that the portion of $$\frac{\displaystyle G_r}{\displaystyle T_s}$$ denotes the performance of receiver equipments.

$\mathrm{C/N_0} = \mathrm{EIRP}-L_{fsp}+G/T+228.6$