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Prob Set 1

This document contains multiple problems involving calculations of electric field intensity, power density, voltage intensity, distance to radio horizon, maximum usable frequency, and characteristic impedance for transmission lines. The problems utilize various equations involving factors like radiated power, distance from source, dielectric constants, antenna heights, critical frequencies, and conductor diameters.

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Henry Dave Demorito
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2K views3 pages

Prob Set 1

This document contains multiple problems involving calculations of electric field intensity, power density, voltage intensity, distance to radio horizon, maximum usable frequency, and characteristic impedance for transmission lines. The problems utilize various equations involving factors like radiated power, distance from source, dielectric constants, antenna heights, critical frequencies, and conductor diameters.

Uploaded by

Henry Dave Demorito
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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Henry Dave D.

Demorito

Problem Set 1

14-6

Determine the electric field intensity for the same point in problem 14.1.

P rad 1000 W
P= P= 2
P=0.2 µ 2 E= √30 Prad E= √30 ( 1000 ) E=8.66 mV
4π R 2
4 π ( 20 km ) m R 20000 m

14-8

For a radiated power Prad = 10kW, determine the voltage intensity of a distance 20 km from the
source.

√30 Prad E= √30 ( 10000 ) E=27.39 mV H= 1 1 AT


E= H= H=7.96
R 20000 m 2 πd 2 π ( 20000 ) m

14-10

If the distance from the source is reduced to one-half its value, what effect does this have on the
power density?

Prad Prad
P rad P= P=
R 2 Therefore, power density increases by a factor of 4.
2
P= R
4π R 2
4 π
2 ( )
4π
4 ( )
14-12

For a dielectric ratio √ € r 2/ € r 1 = 0.8 and an angle of incidence θi =260, determine the angle of
refraction, θr.

sin θ i € r 2 sin 26 =0.8


sin θr
=
√
€ r 1 sinθ r
θr =33.23 ᵒ

14-14

Determine the distance to the radio horizon for an antenna that is 40 ft above the top of a 4000-ft
mountain peak.

h=h1 +h2h=40+ 4000h=4040 ft d= √ 2 hd= √2 ( 4040 )d=89.89 mi

14-16

Determine the power density for a radiated power of 1200 W at distance of 50 km from and
isotropic antenna.
P rad 1200 W
P= 2
P= 2
P=0.038 µ 2
4π R 4 π ( 50 km ) m

14-18

Describe the effects on power density if the distance from a transmit antenna is reduced by a factor
of 3.

Decrease by a factor of 9.

14-20

Determine the maximum usable frequency for a critical frequency of 20 MHz and angle incidence of
350.

fc 20 MHz
MUF= MUF= MUF=24.42 MHz
cos θi cos 35

14-22

Determine the voltage intensity for the same point in problem 14-17.

E=
√30 Prad E= √30 ( 1200 ) E=1.9 mV
R 100000 m

Increase by a factor of 64.

14-24

Determine the change in power density when the distance from the source increase by a factor of 8.

P rad Prad Prad


P= 2 P= 64 P=
4 π (8 R) 4 π (64)( R¿¿ 2)¿ 4 π R2

Increase by a factor of 64
. Determine the characteristic impedance
for an air-filled concentric transmission
line with D/d ratio of 4.

Solution:

Zo = 138/ (√E
r
) log D/d
= 138/ √2.23 log 4

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