What value below represents the best estimate of the distanc

What value below represents the best estimate of the distance over which a plane wave of frequency 100 MHz traveling in FR408 will lose one-half of its power to the medium

A. 2.5m

B.53 m

C. 18m

Here are the values I got using MATLAB, but I cannot find the answer -

Here is a hint Use the low loss dielectric approximation for ?, and solve exp(-2*?*l) = 1/2 for l.

Solution: Given a lossless transmission line, Z0 = 50 , f = 300 MHz, l = 2.5 m, and ZL = (40+ j20) . Since the line is air filled, up = c and therefore, from Eq. (2.48), = up = 2 ×300×106 3×108 = 2 rad/m. Since the line is lossless, Eq. (2.79) is valid: Zin = Z0 µ ZL + jZ0 tanl Z0 + jZL tanl ¶ = 50· (40+ j20)+ j50tan(2 rad/m×2.5 m) 50+ j(40+ j20)tan(2 rad/m×2.5 m) ¸ = 50[(40+ j20)+ j50×0]50+ j(40+ j20)×0 = (40+ j20) .

up = c r = 3×108 2.25 = 2×108 (m/s), = up f = 2up = 2 ×2×108 8 ×107 = 5 m, = up = 8 ×107 2×108 = 0.4 (rad/m), l = 0.4 ×6 = 2.4 (rad).

What value below represents the best estimate of the distance over which a plane wave of frequency 100 MHz traveling in FR408 will lose one-half of its power to

What value below represents the best estimate of the distanc

Solution

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