Question

Give (brief) reasons for the following :

(i) We use the 'sky wave' mode of propagation, of electromagnetic waves, only for frequencies up to 30 to 40 MHz.

(ii) The LOS communication via space waves base (fairly) limited range.

(iii) A mobile phone user gets an 'uninterrupted link to talK' while walking.

Answer 1

(i) The ionosphere can act as a 'reflector' only for e.m. waves of frequency e.m.  pentrate the atmosphere an escape. 

(ii) The range is (fairly) limited because the e.m. . waves loose energy (fairly rapidly) When they glide over the of the earth

(iii)This is because of the presence of a network of base stations '/ cells' which keep on pissing the signals from one base stations /cell to the other.