Question

Calculate the skip distance for the flat earth when a wave is reflected in an ionosphere at a height of 100km at a take-off angle 10°.

(a) 172km

(b) 35.26km

(c) 17.25km

(d) 35.26m

This question was posed to me in an interview.

My doubt is from Multi Hop Propagation in section Virtual Height, Critical Frequency and Muf of Antennas

Answer 1

The correct answer is (b) 35.26km

The best explanation: Take-off angle for the flat earth surface is β = 90 – θi

θi=90-β=90-10=80

skip distance \(d=2h\sqrt{[(secθ_i)^2-1]}=2h\sqrt{[(sec10)^2-1]}=35.26km \)