Antenna and Wave Propagation Quiz
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Questions and Answers

What is the course code for Antenna and Wave Propagation?

EGEC4210

Who is the lecturer for the Antenna and Wave Propagation course?

Sindhu S Nair

What are the two main sets of fields produced by antennas?

  • Reactive field and Fresnel field
  • Electric field and magnetic field
  • Near field and far field (correct)
  • Radiating field and non-radiating field

    • The near field is characterized by the electric and magnetic fields being separate and not forming a propagating wave.

    <p>True</p> Signup and view all the answers

    What is another name for the near field?

    <p>Fresnel zone</p> Signup and view all the answers

    What is the distance from the antenna where the far field begins?

    <p>10 wavelengths</p> Signup and view all the answers

    What are the two types of radiation patterns that antennas can produce?

    <p>Field patterns and power patterns</p> Signup and view all the answers

    What is the three-dimensional representation of the radiation pattern called?

    <p>Spherical coordinates</p> Signup and view all the answers

    What is the name of the angle measured off the z-axis in a spherical coordinate system?

    <p>Theta (θ)</p> Signup and view all the answers

    What is the name of the angle measured counterclockwise off the x-axis in a spherical coordinate system?

    <p>Phi (φ)</p> Signup and view all the answers

    What is the zone or direction in which radiated power is maximum?

    <p>Major lobe</p> Signup and view all the answers

    What is the lobe adjacent to the major lobe?

    <p>Side lobe</p> Signup and view all the answers

    What is the name of the lobe that is the opposite of the major lobe?

    <p>Back lobe</p> Signup and view all the answers

    What two planes are typically used to measure antenna radiation patterns?

    <p>E-field and H-field</p> Signup and view all the answers

    What does HPBW stand for?

    <p>Half-power beam width</p> Signup and view all the answers

    What is another name for the main lobe?

    <p>Boresight</p> Signup and view all the answers

    What is the mathematical expression for the half-power beam width?

    <p>Half power Beam width = 70λ/D</p> Signup and view all the answers

    What is the mathematical expression connecting HPBW and FNBW?

    <p>FNBW = 2 * HPBW</p> Signup and view all the answers

    The unit of HPBW can be either radians or degrees.

    <p>True</p> Signup and view all the answers

    Which type of radiation pattern has a doughnut shape in 3D and a figure-of-eight shape in 2D?

    <p>Omni-directional</p> Signup and view all the answers

    What type of radiation pattern has a sharp directional, pencil-shaped pattern?

    <p>Pencil-beam pattern</p> Signup and view all the answers

    What type of radiation pattern has a fan-shaped pattern?

    <p>Fan-beam pattern</p> Signup and view all the answers

    What type of radiation pattern is non-uniform and pattern-less and is known as a shaped beam?

    <p>Shaped beam pattern</p> Signup and view all the answers

    The isotropic radiation pattern is a practical and widely used pattern in real-world antennas.

    <p>False</p> Signup and view all the answers

    What is the reference point for all types of radiation patterns?

    <p>Isotropic radiation</p> Signup and view all the answers

    What is the formula for calculating the directivity of an antenna?

    <p>Directivity (D) = (Maximum radiation intensity (U_max)) / (Average radiation intensity (U_0))</p> Signup and view all the answers

    What is the formula for calculating the directivity of an antenna in terms of effective aperture area?

    <p>Directivity (D) = (4 * π * Effective aperture area (A_eff)) / (Wavelength (λ) ^ 2)</p> Signup and view all the answers

    What is the formula for calculating the gain of an antenna?

    <p>Gain (G) = Efficiency (η) * Directivity (D)</p> Signup and view all the answers

    What is the name for the output power of a signal when it is concentrated into a smaller area by the antenna?

    <p>Effective Isotropic Radiated Power (EIRP)</p> Signup and view all the answers

    What is the formula for calculating EIRP?

    <p>EIRP = Transmit power (P_T) - Cable loss (L_C) + Antenna gain (G_a)</p> Signup and view all the answers

    What is the name for the angular width of the main lobe at half the peak power level?

    <p>Half-power beam width (HPBW)</p> Signup and view all the answers

    What is the name for the angular distance between the first nulls on either side of the main lobe?

    <p>First null beam width (FNBW)</p> Signup and view all the answers

    What is the name for the wasted radiated power in the transmit mode?

    <p>Sidelobe level</p> Signup and view all the answers

    What is the name for the difference between the main lobe power and the back lobe power, measured in dB?

    <p>Front-to-back ratio</p> Signup and view all the answers

    A well-designed antenna should have CROSSPOL components at least 20 dB below the COPOL in the main-beam region.

    <p>True</p> Signup and view all the answers

    A well-designed antenna should have CROSSPOL components at least 5 to 10 dB below the COPOL in the side lobe regions.

    <p>True</p> Signup and view all the answers

    The polarization of electromagnetic waves never changes during transmission over long distances.

    <p>False</p> Signup and view all the answers

    A horizontally polarized antenna can receive circularly polarized signals, but the signal strength will be reduced.

    <p>True</p> Signup and view all the answers

    If both the transmitter and receiver use circular polarization, the signal can be received regardless of whether they use left-hand or right-hand polarization.

    <p>False</p> Signup and view all the answers

    What is the approximate range for the front-to-back ratio (F/B) for a well-designed antenna?

    <p>20 to 30 dB</p> Signup and view all the answers

    What kind of antenna is used as a reference for antenna gain and has no gain in any direction?

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

    The gain of the idealized isotropic antenna is 0 dB.

    <p>True</p> Signup and view all the answers

    What is the name of the phenomenon where the polarization of electromagnetic waves changes slightly during transmission over long distances?

    <p>Propagation effects</p> Signup and view all the answers

    A transmitting station at 90° relative to an antenna with a 40° beam-width will have no interference with the antenna.

    <p>True</p> Signup and view all the answers

    The gain of a parabolic reflector antenna is independent of the operating frequency.

    <p>False</p> Signup and view all the answers

    The effective radiated power (ERP) of a radio station is always less than its transmit power.

    <p>False</p> Signup and view all the answers

    What is the name for the power gain measured in dB?

    <p>Decibel power gain</p> Signup and view all the answers

    If a radio station has an EIRP of 25 kW and a transmit power of 1.73 kW, what is the antenna gain?

    <p>14.45</p> Signup and view all the answers

    What is the basic STS in SONET?

    <p>STS-1</p> Signup and view all the answers

    What is the data rate of an STS-3 signal?

    <p>155.52 Mbps</p> Signup and view all the answers

    How many DS1 channels can be multiplexed within an STS-3 frame?

    <p>100</p> Signup and view all the answers

    What are the two main types of SONET ring topologies?

    <p>Unidirectional Path-Switched Ring (UPSR) and Bidirectional Line-Switched Ring (BLSR)</p> Signup and view all the answers

    What is the difference between SONET and SDH?

    <p>SONET is a digital hierarchy interface for optical transmission, while SDH is a network node interface, user-network interface, and U reference-point interface to assist BISDN.</p> Signup and view all the answers

    What is the purpose of an STS multiplexer?

    <p>An STS multiplexer multiplexes signals from multiple electrical sources and creates the corresponding optical signal.</p> Signup and view all the answers

    What is the purpose of an add/drop multiplexer?

    <p>Add/drop multiplexers allow insertion and extraction of signals in an STS.</p> Signup and view all the answers

    What is the responsibility of the path layer in SONET?

    <p>The path layer is responsible for the movement of a signal from its source to its destination.</p> Signup and view all the answers

    What is the responsibility of the section layer in SONET?

    <p>The section layer is responsible for the movement of a signal across a physical section.</p> Signup and view all the answers

    What is the responsibility of the photonic layer in SONET?

    <p>The photonic layer corresponds to the physical layer of the OSI model, and includes physical specifications for the optical fiber channel.</p> Signup and view all the answers

    What encoding scheme does SONET use?

    <p>NRZ encoding</p> Signup and view all the answers

    How many wavelengths away should you be to be in the far field?

    <p>10 wavelengths</p> Signup and view all the answers

    What is the relationship between the electric and magnetic fields in the far field?

    <p>They are orthogonal to each other and to the direction of propagation.</p> Signup and view all the answers

    What is the purpose of scattering parameters?

    <p>Scattering parameters describe the input-output relationships between ports in an electrical system.</p> Signup and view all the answers

    What does S11 represent in a two-port network?

    <p>The input port voltage reflection coefficient</p> Signup and view all the answers

    What is the purpose of the S-parameter matrix?

    <p>The S-parameter matrix can be used to determine reflection coefficients and transmission gains from both sides of a two-port network.</p> Signup and view all the answers

    What are the two common types of radiation patterns?

    <p>Field patterns and power patterns</p> Signup and view all the answers

    What type of antenna radiates power equally in all directions?

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

    What is the purpose of the half-power beam width (HPBW)?

    <p>The HPBW is the angular separation in which the magnitude of the radiation pattern decreases by 50% (or -3dB) from the peak of the main beam.</p> Signup and view all the answers

    What is the purpose of the first null beam width (FNBW)?

    <p>The FNBW is the angular span between the first pattern nulls adjacent to the main lobe.</p> Signup and view all the answers

    What is the purpose of the front-to-back ratio (F/B)?

    <p>The F/B is a measure of how much power is radiated in the back direction compared to the front direction.</p> Signup and view all the answers

    What is the purpose of the side-lobe level (SLL)?

    <p>The SLL is a measure of how much power is radiated in the side lobes compared to the main lobe.</p> Signup and view all the answers

    What is the purpose of the effective radiated power (ERP)?

    <p>The ERP is a measure of the total power that is radiated by an antenna, taking into account the power loss from the transmission line and the antenna's gain.</p> Signup and view all the answers

    What is the formula for calculating directivity?

    <p>D = 4πAeff/λ²</p> Signup and view all the answers

    What is the purpose of polarization?

    <p>Polarization refers to the orientation of the electric and magnetic fields with respect to the earth.</p> Signup and view all the answers

    What is the purpose of cross-polarization?

    <p>Cross-polarization is the undesired orthogonal polarization.</p> Signup and view all the answers

    Which of these is NOT a circuit quantity of an antenna?

    <p>Current distribution</p> Signup and view all the answers

    The effective length of an antenna is the ratio of the voltage across the open terminals to the field strength of the incident wave.

    <p>True</p> Signup and view all the answers

    What is the term for the area of the receiving antenna that captures most of the power from the incoming wave front?

    <p>Effective area</p> Signup and view all the answers

    The S-parameter S12 represents the power transferred from port 2 to port 1.

    <p>True</p> Signup and view all the answers

    The ______ is approximately 10 wavelengths from the antenna and represents the radio wave with the combined electric and magnetic fields.

    <p>Far field</p> Signup and view all the answers

    Which of the following is NOT a common parameter used to describe antenna radiation patterns?

    <p>Polarization</p> Signup and view all the answers

    Match these parameters with their corresponding descriptions

    <p>Main lobe = The zone or direction where the radiated power is at its maximum Nulls = The zone or direction where the radiated power is at its minimum Side lobe = The lobe adjacent to the major lobe. Back lobe = The lobe opposite to the major lobe.</p> Signup and view all the answers

    The radiation pattern of an antenna is typically measured in two planes: the E-field plane and the H-field plane.

    <p>True</p> Signup and view all the answers

    What is the term for the angle between the first pattern nulls adjacent to the main lobe?

    <p>First null beam width</p> Signup and view all the answers

    Which of these is a type of radiation pattern?

    <p>All of the above</p> Signup and view all the answers

    The power gain of an antenna is the ratio of the maximum power density in a given direction to the average power density over all directions.

    <p>False</p> Signup and view all the answers

    The half-power beam width is determined by the angle at which the power density is half of the maximum power density.

    <p>True</p> Signup and view all the answers

    What is the formula for calculating the EIRP (Effective Isotropic Radiated Power) of an antenna?

    <p>EIRP = PT - LC + GA</p> Signup and view all the answers

    The directivity of an antenna is directly proportional to the effective aperture area.

    <p>True</p> Signup and view all the answers

    The gain of an antenna is equal to its directivity multiplied by the antenna's efficiency.

    <p>True</p> Signup and view all the answers

    Co-polarization refers to the desired polarization of an antenna, while cross-polarization refers to the undesired orthogonal polarization.

    <p>True</p> Signup and view all the answers

    What does horizontally polarized mean in terms of antenna orientation?

    <p>The electric field is parallel to the ground.</p> Signup and view all the answers

    Circular polarization refers to the situation where the electric and magnetic fields rotate as they leave the antenna.

    <p>True</p> Signup and view all the answers

    What are the two types of fields that antennas produce?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is NOT a common parameter of antenna radiation patterns?

    <p>Polarization</p> Signup and view all the answers

    The far field is the region where the electric and magnetic fields are in phase with each other.

    <p>True</p> Signup and view all the answers

    What is the approximate distance for the far-field region?

    <p>10 wavelengths from the antenna</p> Signup and view all the answers

    The term Effective Radiated Power (ERP) is used when calculating the radiated power using a half-wave dipole as the reference.

    <p>True</p> Signup and view all the answers

    What is the mathematical relationship between the First Null Beam Width (FNBW) and the Half Power Beam Width (HPBW)?

    <p>FNBW = 2HPBW</p> Signup and view all the answers

    What is the main purpose of using S-parameters in antenna analysis?

    <p>To describe the power transfer between ports or terminals in an electrical system</p> Signup and view all the answers

    What is the purpose of the "Add/Drop Multiplexer" in SONET?

    <p>It allows adding or removing signals from a specific path within the SONET network.</p> Signup and view all the answers

    What does the term "beamwidth" refer to in antenna system?

    <p>The angular width of an antenna's main lobe</p> Signup and view all the answers

    Which of the following is NOT a type of radiation pattern?

    <p>Hemispherical</p> Signup and view all the answers

    The isotropic antenna is a practical and realistic antenna type used in real-world applications.

    <p>False</p> Signup and view all the answers

    What is the term for a side lobe that has the highest strength among all side lobes?

    <p>Largest side lobe</p> Signup and view all the answers

    What is the difference between "co-polarization" and "cross-polarization" in terms of antenna radiation?

    <p>Co-polarization refers to the desired polarization of the antenna, while cross-polarization represents the undesired orthogonal polarization.</p> Signup and view all the answers

    Which of the following is NOT a benefit of using a higher side lobe level in an antenna?

    <p>Reduced interference</p> Signup and view all the answers

    Study Notes

    Course Information

    • Course Code: EGEC4210
    • Lecturer: Sindhu S Nair
    • Course Title: Antenna and Wave Propagation

    Course Outline

    • Outcome #4: Evaluate fundamental antenna parameters for effective radiation.
    • Outcome #5: Analyze antenna arrays for isotropic point sources and dipoles.
    • Outcome #6: Determine and analyze radiation patterns of different antenna types.

    Antenna Parameters

    • Circuit Quantities: Antenna impedance (Za), Radiation resistance (Rr), Antenna temperature (Ta)
    • Physical Quantities: Size, Weight, Current distribution
    • Space Quantities: Field patterns, Polarization (LP, CP, EP), Power patterns, Beam area, Directivity (D), Gain (G), Effective aperture (Ae), Radar cross-section (σ)

    Effective Length

    • Used to determine polarization efficiency.
    • Definition: The ratio of voltage at open terminals of a receiving antenna to field strength of the incident wave front (in the same polarization direction).

    Effective Area

    • The area of the receiving antenna that absorbs most power from the incoming wave front.
    • Related to the maximum power obtained and the actual antenna area.

    Scattering Parameters

    • Describe the input-output relationship between ports/terminals in an electrical system.
    • S12: Power transferred from port 2 to port 1.
    • S21: Power transferred from port 1 to port 2.
    • Snm: Power transferred from port m to port n in a general network.

    Near Field and Far Field

    • Antennas produce near and far fields.
    • Near Field: Region directly around the antenna where electric and magnetic fields are separate; contains transmitted information, weakens with distance (approximately by the quadruple of the distance). Also referred to as the Fresnel zone.
    • Far Field: Region approximately 10 wavelengths from the antenna; is the radio wave; contains electric and magnetic fields.
    • Reactive near field ≤ 0.62 × (D3/λ)1/2
    • Radiating near field (Fresnel region) ≤ 2D2/λ
    • Far field ≥ 2D2/λ

    Radiation Pattern

    • Graphically shows the radiation power pattern as a function of angular position and distance from the antenna.
    • Three-dimensional quantity, variation of field/power proportional to field squared.
    • Represented mathematically using spherical coordinates (E(θ, φ) and H(θ, φ)), where θ is the angle measured off the z-axis and φ is the angle measured counter-clockwise from the x-axis.

    Different Types of Radiation Patterns

    • Isotropic: Uniform radiation in all directions.
    • Omni-directional: Doughnut shape in 3D; figure-of-eight in 2D.
    • Directional: Pencil- or fan-shaped radiated power.

    Lobe Formation

    • Major lobe: Area of maximum radiated power and indicates directivity.
    • Side lobes: Areas with weaker radiation, adjacent to the major lobe.
    • Back lobe: Lobe opposite to the main lobe; often significant energy loss.

    Half Power Beam Width (HPBW)

    • Angular separation where the radiation pattern magnitude decreases by 50% (or -3dB) from the main beam peak.

    First Null Beam Width (FNBW)

    • Angular span between the first nulls adjacent to the main lobe.

    Directivity

    • Ratio of maximum radiation intensity to the average radiation intensity over all directions.
    • equation for large antenna- D = 32400 / θeθh
    • equation for small antenna- D= 41253 / θeθh where θe, θh are in degrees.

    Effective Radiated Power (ERP)

    • Radiated power calculated by reference to a half-wave dipole rather than an isotropic antenna.
    • ERP (dBW) = EIRP (dBW) – 2.15 dBi

    Co-Polarization and Cross-Polarization

    • Co-polar (COPOL): Desired polarization.
    • Cross-polar (CROSSPOL): Undesired orthogonal polarization (should be low to minimize interference).

    Antenna Gain

    • Given in ratio (e.g., 800) or decibels (e.g., 29 dB).
    • Gain formula for parabolic reflector: G = η(πr2/λ2) where:
      • η = Efficiency
      • r = Radius of the reflector
      • λ = Wavelength

    Additional Information

    • dB Calculations (Example): EIRP = Pt × G (Where G = gain in linear scale and Pt = transmitter power)

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    Antenna and Wave Propagation PDF
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    Description

    This quiz focuses on fundamental antenna parameters, analyzing arrays, and evaluating radiation patterns. Test your knowledge of key concepts such as antenna impedance, radiation resistance, and effective length in various polarization types.

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