A radio transmitting station operating at a frequency of 170 MHz has two identic
ID: 1401161 • Letter: A
Question
A radio transmitting station operating at a frequency of 170 MHz has two identical antennas that radiate in phase. Antenna B is 7.20 m to the right of antenna A. Consider point P between the antennas and along the line connecting them, a horizontal distance x to the right of antenna A. For what values of x will constructive interference occur at point P? (Enter your answers from smallest to largest starting with the first answer blank. Enter NONE in any remaining answer blanks.)
m m m m m m m m mExplanation / Answer
f = 170 MHz
lambda = c/f = 3 x 10^8 / 170 x 10^6 Hz = 1.76 m
for constructive
r1 - r2 = m*lambda
r1 + r2 = 7.2
r2 = 7.2 - r1
2r1 - 7.2 = m(1.76)
here m = 0 , +-1 , +-2 , +-3 ,.......
for m = 0
r1 = 3.6 m
if m = 1
r1 = 4.48
if m = 2
r1 = 5.36
if m = 3
r1 = 6.24
if m = 4
r1 = 7.12
m = 5 is not possible
now m = -1
r1 = 2.72 m
if m = -2
r1 = 1.84 m
if m = -3
r1 = 0.96 m
if m = -4
r1 = 0.08 m
if m = -5
no =t possible for this range