The expression for the maximum line of right distance dm between two transmitting and receiving antenna is given by, dm=√2RhT+√2RhR Let the height of receiving antenna hR=x Substitute the values in the above expression. 40‌‌=√2×6400×45×10−3+√2×6400×x×10−3 40‌‌=24+√2×6.4×x x‌‌=‌