(Q).Calculate the attenuation at a frequency of 600MHz when the distance between transmiting and receiving antenna is 40km and gains are 20 dB

G_T = G_R =20 dB

d = 40 km

f = 600 MHz

then , (P_r /P_t ) = G_T (dB)+G_R (dB)-L_s (dB) ———————(a)

where, L_s (dB) = 32.45+20log(f)+20log(d) (where f in MHz and d in km)

=32.45+20log(600)+20log(40)

L_s (dB) = 120.056 dB —————(b)

Hence, from eq(a) and eq(b)

(P_r /P_t ) = 20+20-120.056

= – 80.056 dB

Here Negative sign indicates attenuation