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Questions and Answers

Which action is explicitly allowed concerning the slides?

  • Transmitting them over wireless channels
  • Using them solely in their current form
  • Adding to them for tailored instruction (correct)
  • Reproducing them for commercial purposes

What format are the slides available in for faculty?

  • HTML
  • PDF
  • Word Document
  • PowerPoint (correct)

What can be done with the slides in terms of content?

  • Only add new slides without changes to existing ones
  • Only delete them without any modifications
  • Modify, add, and delete slides as needed (correct)
  • Only use them as they are provided

Who is the primary audience for these slides?

<p>Faculty members using them for instruction (C)</p> Signup and view all the answers

What does the statement imply about the work of the authors?

<p>The authors have put in significant effort. (C)</p> Signup and view all the answers

Which of the following can be inferred about the request made to the authors?

<p>It is a formal request for contributions. (D)</p> Signup and view all the answers

What is likely the primary focus of the authors' work mentioned?

<p>Wireless communication. (B)</p> Signup and view all the answers

Which of the following best describes the nature of the work referenced in the content?

<p>It is substantial and noteworthy. (D)</p> Signup and view all the answers

What might be a reason for requesting something from the authors?

<p>To acknowledge their substantial efforts. (C)</p> Signup and view all the answers

What is the primary focus of the material authored by Cory Beard and William Stallings?

<p>Information security (A)</p> Signup and view all the answers

Which of the following years is associated with the publication of the material by Cory Beard and William Stallings?

<p>2016 (C)</p> Signup and view all the answers

What type of educational material is produced by Pearson Education, Ltd. in conjunction with Cory Beard and William Stallings?

<p>Textbooks (B)</p> Signup and view all the answers

Which aspect of information security is MOST likely covered in the work of Cory Beard and William Stallings?

<p>Threat assessment and management (B)</p> Signup and view all the answers

In the context of educational materials, what does the copyright year of 2016 suggest about the content?

<p>It may include information relevant to technology from that period (D)</p> Signup and view all the answers

What is the primary function of an antenna in communication?

<p>To radiate and collect electromagnetic energy (D)</p> Signup and view all the answers

Which type of antenna radiates power equally in all directions?

<p>Isotropic antenna (B)</p> Signup and view all the answers

What determines the length of a half-wave dipole antenna?

<p>It should be one half of the wavelength of the radio signal (D)</p> Signup and view all the answers

In which scenario can the same antenna be used for both functions?

<p>In two-way communication (A)</p> Signup and view all the answers

What is the required length of a quarter-wave vertical antenna?

<p>One quarter of the radio signal wavelength (A)</p> Signup and view all the answers

What is the primary function of a parabolic reflective antenna?

<p>To reflect and focus incoming radio waves into a narrow beam (C)</p> Signup and view all the answers

Where is the receiver typically positioned in a parabolic reflective antenna design?

<p>Above the center of the antenna (C)</p> Signup and view all the answers

Which statement correctly describes the shape of a parabolic reflective antenna?

<p>It is a bowl-shaped antenna (C)</p> Signup and view all the answers

What is the expected outcome of using a parabolic reflective antenna?

<p>It focuses radio waves into a narrow beam for more precise reception (D)</p> Signup and view all the answers

Which of the following best describes the incoming radio waves in relation to the parabolic reflective antenna?

<p>They are incoming signals that are directed towards the receiver (A)</p> Signup and view all the answers

What is the primary purpose of adjusting signal amplitudes and phases in a directional antenna array?

<p>To establish a specific directional pattern (D)</p> Signup and view all the answers

What defines antenna gain?

<p>Ratio of power directed in a specific direction compared to an isotropic antenna (B)</p> Signup and view all the answers

Which propagation mode involves signals being reflected from the ionized layer of the atmosphere?

<p>Sky-wave propagation (D)</p> Signup and view all the answers

What is the maximum distance formula for LOS propagation based on antenna heights h1 and h2?

<p>d = 3.57K(h1 + h2) (B)</p> Signup and view all the answers

Which factor primarily influences the effective line-of-sight distance?

<p>Refraction of microwaves (B)</p> Signup and view all the answers

What characterizes ground-wave propagation?

<p>It tends to follow the contour of the earth. (B)</p> Signup and view all the answers

When calculating line-of-sight distance, what is the rule of thumb adjustment factor K typically set to?

<p>4/3 (B)</p> Signup and view all the answers

In line-of-sight communication, what is a major limitation that affects signal transmission?

<p>Obstruction by physical structures (D)</p> Signup and view all the answers

Which type of antenna is best known for its high directivity and gain?

<p>Parabolic reflective antenna (C)</p> Signup and view all the answers

Which of the following describes a necessary condition for line-of-sight propagation?

<p>Transmitting and receiving antennas must be in direct line of sight. (D)</p> Signup and view all the answers

Flashcards

Wireless Channel

The medium through which wireless signals travel.

Channel Impairments

The fading and distortion that wireless signals experience as they travel through the environment.

Path Loss

The weakening of a signal as it travels further from the source.

Multipath Propagation

The reflection and scattering of radio waves by objects in the environment.

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Fading

Variations in the strength and phase of a received signal caused by multipath propagation.

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Substantial work

Authors put significant effort and time into their work.

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Request

A formal request for something.

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Following

The things requested from the authors.

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Wireless communication

Communication that relies on radio waves to transmit data.

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String

A string of characters, like a sentence or a word, that can be manipulated and processed.

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Copyright

Copyright describes the legal rights of creators to control the copying, distribution, and other uses of their original works.

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Copyright Year

The year in which a piece of work or creative content was protected by copyright.

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Copyright Rights

The legal rights granted to creators to control the copying, distribution, and other uses of their original works.

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Copyright Symbol

Copyright © symbol, indicating that a piece of work is protected by copyright and its use is restricted by law.

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Antenna

A conductor or system of conductors that radiates electromagnetic energy for transmission or collects it for reception.

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Isotropic Antenna

An antenna that radiates power equally in all directions. This is an idealized model.

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Half-wave Dipole Antenna

A type of antenna with a length equal to half the wavelength of the radio wave.

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Quarter-wave Vertical Antenna (Marconi Antenna)

A type of antenna with a length equal to one quarter of the wavelength of the radio wave.

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Two-Way Communication Antenna

An antenna can be used for transmitting and receiving radio waves simultaneously.

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Parabolic Antenna

A type of antenna shaped like a bowl that gathers and focuses radio waves into a concentrated beam.

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How does a parabolic antenna work?

The radio waves are bounced off the dish's curved surface and directed towards a receiver.

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Receiver Location in a parabolic antenna

The receiver is usually positioned above the center of the dish, where all the reflected waves converge.

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Antenna Beam and Gain

The narrower the beam, the more focused the signal and the greater the antenna's gain.

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Applications of parabolic antennas

Parabolic antennas are commonly used in satellite communication, radar systems, and radio telescopes.

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Antenna Array

A configuration of multiple antennas where the signal amplitude and phase are adjusted to focus the signal in a specific direction.

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Antenna Gain

The power output of an antenna in a specific direction compared to a theoretical omnidirectional antenna.

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Effective Area

The area that an antenna effectively captures radio waves, related to its physical size and shape.

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Ground Wave Propagation

Radio waves traveling along the curvature of the earth, used for AM radio and low frequencies.

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Sky Wave Propagation

Radio waves reflected off the ionosphere back to Earth, used for long-distance communications.

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Line-of-Sight Propagation

Radio waves traveling directly between antennas, requiring a clear line of sight.

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Radio Line of Sight

The distance between an antenna and the horizon, accounting for atmospheric refraction.

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Maximum LOS Distance

The maximum distance between two antennas for line-of-sight propagation, influenced by antenna heights.

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Refraction

The bending of electromagnetic waves as they travel through different mediums, altering their direction.

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Refraction Adjustment Factor (K)

The adjustment factor used in radio line of sight calculations to account for signal bending due to atmospheric refraction.

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Study Notes

Chapter 6: The Wireless Channel

  • Wireless communication networks and systems are discussed in this chapter.
  • Slides are available for faculty in PowerPoint format and can be freely added, modified, and removed to meet student needs.
  • The slides represent substantial work from the authors; therefore, if used in a class setting or posted online, proper attribution to the textbook and copyright notice is requested.

Antennas

  • An antenna is an electrical conductor or system of conductors.
  • Transmission: Radiates electromagnetic energy into space.
  • Reception: Collects electromagnetic energy from space.
  • Two-way communication utilizes the same antenna for transmission and reception.

Types of Antennas

  • Isotropic antenna: Idealized; radiates power equally in all directions.
  • Dipole antennas:
    • Half-wave dipole (Hertz antenna): Antenna length is half the wavelength.
    • Quarter-wave vertical antenna (Marconi antenna): Antenna length is one-quarter of the wavelength.
  • Parabolic reflective antenna: Bowl-shaped antenna that focuses radio waves into a narrow beam.
  • Directional antennas: Arrays of antennas with adjusted signal amplitudes and phases to create a directional pattern.

6.2 Simple Antennas

  • Basic antenna structures

6.4 Parabolic Reflective Antennas

  • Diagram illustrating the parabolic reflective antenna with its vertex and focus.

Antenna Gain

  • Antenna gain: Power output in a particular direction compared to a perfect omnidirectional antenna (isotropic antenna).
  • Effective area: Related to the physical size and shape of the antenna.
  • Relationship between antenna gain and effective area:
    • G = 4πAe / λ²
    • Where: G = antenna gain, Ae = effective area, λ = carrier wavelength

Table 6.2 Antenna Gains and Effective Areas

  • Tabular data showing antenna type, effective area, and power gain relative to isotropic.

Example 6.1

  • Calculating the effective area and antenna gain of a parabolic reflective antenna with a 2-meter diameter operating at 12 GHz.

Propagation Modes

  • Ground-wave propagation: Follows the Earth's contour, propagates over considerable distances, frequencies up to 3 MHz (e.g., AM radio).
  • Sky-wave propagation: Signal is reflected by the ionosphere.
  • Line-of-sight propagation: Transmitting and receiving antennas must be in line of sight; Satellite communication, signal above 30 MHz not reflected by ionosphere; Ground communication, antennas within effective line of sight due to refraction.

6.5 Wireless Propagation Modes

  • Diagrams illustrating different propagation modes (ground wave, sky wave).

Ground Wave Propagation

  • Detailed description of ground wave propagation

Sky Wave Propagation

  • Detailed description of sky wave propagation

Line-of-Sight Propagation

  • Transmitting and receiving antennas must be within line of sight.
  • Satellite communication, signal above 30 MHz not reflected by ionosphere.
  • Refraction: bending of microwaves by the atmosphere.
  • Velocity of electromagnetic wave varies with medium density
  • Wave bends at the boundary between different media

Line-of-Sight Equations

  • Optical line of sight: d = 3.57√h
  • Effective, or radio, line of sight: d = 3.57√Kh
    • Where: d = distance between antenna and horizon (km), h = antenna height (m), K = adjustment factor for refraction.

6.7 Optical and Radio Horizons

  • Diagram distinguishing optical horizon and radio horizon.

Line-of-Sight Equations (continued)

  • Maximum distance between two antennas: 3.57√(Kh₁ + Kh₂)
    • h₁ = height of the first antenna, h₂ = height of the second antenna
    • Example problem illustrating calculation

Exercise

  • Problems related to calculating antenna distances and heights given certain parameters.

Example 6.2

  • Problem solving example determining height in relation to distance. Demonstrates how raising antennas above ground level can be more efficient.

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Wireless Communication Networks and Systems: Chapter 6

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This quiz focuses on the purpose and use of presentation slides created by Cory Beard and William Stallings. It addresses the format available for faculty and implications regarding the authors' work. Test your understanding of the content and intended audience for these educational materials.

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