Question

there are three screens 20 m apart from other and 30 40 and 25 m high the first screen is 30 m from the TX the last screen is 100 m from the RX the TX is 1.5 m high the rx is 30 m high compute the attenuation diffraction at 900 MHz by the deygout method.

Answer 1

Step-by-step explanation:

To compute the attenuation due to diffraction at 900 MHz using the Deygout method, we need to calculate the diffraction loss for each screen and then sum them up.

The Deygout method provides the following formula to calculate the diffraction loss:

Ld = 17.3 + 40log10(d) + 20log10(h) - 9log10(D)

Where:

Ld is the diffraction loss in decibels (dB)

d is the distance between the TX (transmitter) and the screen in meters

h is the height of the screen in meters

D is the distance between the TX and the RX (receiver) in meters

Let's calculate the diffraction loss for each screen:

For the first screen (30 m from TX, 30 m high):

Ld1 = 17.3 + 40log10(30) + 20log10(30) - 9log10(100)

≈ 17.3 + 40(1.477) + 20(1.477) - 9(2)

≈ 17.3 + 59.08 + 29.54 - 18

≈ 87.92 dB

For the second screen (50 m from TX, 40 m high):

Ld2 = 17.3 + 40log10(50) + 20log10(40) - 9log10(100)

≈ 17.3 + 40(1.699) + 20(1.602) - 9(2)

≈ 17.3 + 67.96 + 32.04 - 18

≈ 99.3 dB

For the third screen (80 m from TX, 25 m high):

Ld3 = 17.3 + 40log10(80) + 20log10(25) - 9log10(100)

≈ 17.3 + 40(1.903) + 20(1.397) - 9(2)

≈ 17.3 + 76.12 + 27.94 - 18

≈ 103.36 dB

Finally, we sum up the diffraction losses:

Total diffraction loss = Ld1 + Ld2 + Ld3

= 87.92 + 99.3 + 103.36

≈ 290.58 dB