Chapter 13, WAVE PROPAGATION Video Solutions, Electronic Communications: A Systems Approach

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Problem 1

Explain why an antenna can be thought of as a transducer.

Victor Salazar

Numerade Educator

02:23

Problem 2

List the similarities and dissimilarities between light waves and radio waves.

Averell Hause

Carnegie Mellon University

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Problem 4

What is horizontal and vertical polarization of a radio wave?

James Kiss

Numerade Educator

02:08

Problem 5

What kinds of fields emanate from a transmitting antenna, and what relationships do they have to each other?

Manish Jain

Numerade Educator

01:20

Problem 6

Define wavefront.

Ajay Singhal

Numerade Educator

04:31

Problem 7

Calculate the power density in watts per square meter (on Earth) from a 10-W satellite source that is $22,000 \mathrm{mi}$ from Earth. $\left(6.35 \times 10^{-16} \mathrm{~W} / \mathrm{m}^2\right)$

Khoobchandra Agrawal

Numerade Educator

Calculate the power received from a $20-\mathrm{W}$ transmitter, $22,000 \mathrm{mi}$ from Earth, if the receiving antenna has an effective area of $1600 \mathrm{mi}^2 .\left(2.03 \times 10^{-12} \mathrm{~W}\right)$

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01:33

Problem 9

Calculate the electric field intensity, in volts per meter, $20 \mathrm{~km}$ from a $1-\mathrm{kW}$ source. How many decibels down will that field intensity be if the distance is an additional $30 \mathrm{~km}$ from the source? $(8.66 \mathrm{mV} / \mathrm{m}, 7.96 \mathrm{~dB})$

Ajay Singhal

Numerade Educator

Problem 10

Calculate the characteristic impedance of free space using two different methods.

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03:44

Problem 11

How does the field strength of a standard broadcast station vary with distance from the antenna?

Alex Moore

Numerade Educator

01:57

Problem 14

With the aid of Snell's law, fully explain the process of refraction for an electromagnetic wave.

Charles Machakwa

Numerade Educator

01:37

Problem 15

What is diffraction of electromagnetic waves? Explain the significance of the shadow zone and how it is created.

Ajay Singhal

Numerade Educator

02:57

Problem 16

Write the equation for the coefficient of reflection. $\left(\rho=\varepsilon_r / \varepsilon_i\right.$ )

Mirza Aslam Beig

Numerade Educator

Problem 17

Define refraction.

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01:44

Problem 18

Define shadow zone.

Prabhu Ramji

Numerade Educator

01:42

Problem 19

List the three basic modes whereby an electromagnetic wave propagates from a transmitting to a receiving antenna.

Khoobchandra Agrawal

Numerade Educator

01:03

Problem 20

Describe ground-wave propagation in detail.

Hast Aggarwal

Numerade Educator

01:07

Problem 21

Explain why ground-wave propagation is more effective over seawater than desert terrain.

Averell Hause

Carnegie Mellon University

03:31

Problem 22

What is the relationship between operating frequency and ground-wave coverage?

Coleman Green

Numerade Educator

00:43

Problem 23

What are the lowest frequencies useful in radio communications?

Kyle Godbey

Numerade Educator

01:58

Problem 24

Fully explain space-wave propagation. Explain the difference between a direct and reflected wave.

Salamat Ali

Numerade Educator

01:16

Problem 25

List the course of events in the process of sky-wave propagation.

Mayukh Banik

Numerade Educator

02:06

Problem 26

Provide a detailed discussion of the ionosphere-its makeup, its layers, its variations, and its effect on radio waves.

Wan Deng

Numerade Educator

02:40

Problem 27

What effects do sunspots and the aurora borealis have on radio communications?

Rodger Claar

Numerade Educator

00:30

Problem 28

Define and describe critical frequency, critical angle, and maximum usable frequency (MUF). Explain their importance to sky-wave communications.

Hast Aggarwal

Numerade Educator

Problem 29

What is the optimum working frequency, and what is its relationship to the MUF?

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03:14

Problem 30

What frequencies have substantially straight-line propagation characteristics analogous to those of light waves and are unaffected by the ionosphere?

John Biddulph

Numerade Educator

01:02

Problem 31

What radio frequencies are useful for long-distance communications requiring continuous operation?

Narayan Hari

Numerade Educator

01:05

Problem 32

In radio transmissions, what bearings do the angle of radiation, density of the ionosphere, and frequency of emission have on the length of the skip zone?

Ankur S

Numerade Educator

00:33

Problem 33

Why is it possible for a sky wave to "meet" a ground wave $180^{\circ}$ out of phase?

Mayukh Banik

Numerade Educator

02:10

Problem 34

What is the process of tropospheric scatter? Explain under what conditions it might be used.

Amita Prajapat

Numerade Educator

01:31

Problem 35

What is the purpose of a diversity antenna receiving system?

Mayukh Banik

Numerade Educator

Problem 36

List and explain three types of diversity reception schemes.

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Problem 37

What is skipping?

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Problem 38

Define fading.

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02:10

Problem 39

What happens when a signal is above the critical frequency?

Amita Prajapat

Numerade Educator

01:07

Problem 40

What is satellite communications? List reasons for their increasing popularity.

Narayan Hari

Numerade Educator

Problem 41

Explain the differences between GEO and LEO satellite systems. Describe the advantages and disadvantages of each system.

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Problem 42

Describe a typical VSAT installation. How does it differ from an MSAT system?

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Problem 43

Explain the methods of multiplexing in SATCOM systems, and provide the advantages of TDMA over FDMA.

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02:20

Problem 44

Use the satellite footprint of the Telstar 5 provided in Figure 13-16 to determine the expected EIRP for the signal in your area.

Kyle Godbey

Numerade Educator

Problem 45

An Earth station is located at $98^{\circ} \mathrm{W}$ longitude and $35.1^{\circ} \mathrm{N}$ latitude. Determine the azimuth and elevation angles for the Earth station if the antenna is to be pointed at a satellite parked at $92^{\circ} \mathrm{W}$ longitude.

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01:42

Problem 46

What two signals does a GPS satellite transmit? How are they used, and what frequencies are being used?

Khoobchandra Agrawal

Numerade Educator

03:57

Problem 47

What is the distance to a satellite parked at $69^{\circ} \mathrm{W}$ longitude from an Earth station located at $29^{\circ} \mathrm{N}$ latitude and $110^{\circ} 36^{\prime} 20^{\circ} \mathrm{W}$ longitude? Calculate the round-trip time delay for a signal traveling from the Earth station to the satellite and back.

Jonathon Brumley

Numerade Educator

03:23

Problem 48

Define apogee and perigee.

Shoukat Ali

Other Schools

04:56

Problem 49

What is the altitude and orbital period of the Iridium LEO satellites? How many satellites are there, and what type of orbital pattern is used?

Nishant Kumar

Numerade Educator

Problem 50

Calculate the noise factor (NF) in dB for a $100^{\circ} \mathrm{LNA}$.

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Problem 51

Determine the figure of merit for a satellite Earth station with the following specifications:
Antenna Gain- $48 \mathrm{dBi}$
Reflector noise temperature- $28 \mathrm{~K}$
LNA noise temp- $55 \mathrm{~K}$
Noise temp. (various components)- $3 \mathrm{~K}$

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Problem 52

Calculate the free-space path loss for a link between a satellite parked at $89^{\circ} \mathrm{W}$ longitude and an Earth station at $29^{\circ} \mathrm{N}$ latitude and $11036^{\prime} 20^{\circ} \mathrm{W}$ longitude. The downlink frequency is $11.974 \mathrm{GHz}$.

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Problem 53

Prepare a satellite link budget for an Earth station located at $35^{\circ} 10^{\prime} \mathrm{N}$ latitude and $99^{\circ} 15^{\prime} \mathrm{W}$ longitude that will be linked to a satellite parked at $91^{\circ} \mathrm{W}$ longitude. A data rate of $6 \mathrm{Mbps}$ using 8-PSK modulation is being used, which requires a bandwidth of $2 \mathrm{MHz}$ ( $63 \mathrm{~dB}$ ). The required $\mathrm{C} / \mathrm{N}$ at the satellite is $8 \mathrm{~dB}$, and the required $\mathrm{C} / \mathrm{N}$ at the Earth station is $15 \mathrm{~dB}$. Comment on the results obtained from the satellite link budget in regard to whether the received $\mathrm{C}$ / $\mathrm{N}$ is or is not acceptable.
$$
\begin{array}{ll}
\text { Earth Station } & \\
\text { Uplink frequency } & 14.135 \mathrm{GHz} \\
\text { Antenna Diameter } & 5.0 \text { meters } \\
\text { Antenna Efficiency } & 0.65 \\
\text { Earth Station G/T } & 31.2 \mathrm{dBK} \\
\text { Transmit EIRP } & 62 \mathrm{dBW}(4.5 \mathrm{~W}) \\
\text { Satellite } & \\
\text { Downlink Frequency } & 11.752 \mathrm{GHz} \\
\text { Satellite EIRP } & 38.2 \mathrm{dBW} \\
\text { Satellite G/T } & 0.9 \mathrm{dBK}
\end{array}
$$

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Problem 54

A user complains about "interference." How can you determine whether this is electromagnetic interference (EMI) or radio-frequency interference (RFI)?

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01:48

Problem 55

Calculate the radio horizon for a 500 - $\mathrm{ft}$ transmitting antenna and a receiving antenna of $20 \mathrm{ft}$. Calculate the required height increase for the receiving antenna if a 10 percent increase in radio horizon were required. $(37.9 \mathrm{mi}, 31.2 \mathrm{ft}$ )

Suzanne W.

Numerade Educator

00:38

Problem 56

In the strictest sense, define skip distance and skip zone.

Vicki Stebbins

Numerade Educator

00:57

Problem 57

You will be receiving sky waves. In what ways can you anticipate fading to occur?

Keshav Singh

Numerade Educator

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