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Communications 4 > For quiz 3 > Flashcards

For quiz 3 Flashcards

1
Q

Radio Frequency Bands

A

ELF (3 - 30 Hz)
SLF (30 - 300Hz)
ULF (300 - 3000 Hz)
VLF (3 - 30 kHz)
LF (30 -300 kHz)
MF (300 - 3000 kHz)
HF (3 - 30 MHz)
VHF (30 -300 MHZ)
UHF ( 300 - 3000 MHz)
SHF (3 - 30 GHz)
EHF (30 -300 GHz)

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2
Q

the wave environment is free from everything except the wave itself.

A

Free space

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3
Q

The orientation of the E-field component of the TEM wave is called its ____

A

Polarization

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4
Q

If the direction remains constant with time at a fixed point in space, the field is said to be ______.

A

Linearly Polarized

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5
Q

Composed of magnetic field(H) and electric field(E)

A

Transverse Electrmomagnetic Wave (TEM)

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6
Q

The ____ of the TEM wave depends on the medium where it travels.

A

Velocity

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7
Q

Number of cycles per second

A

Frequency

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8
Q

The distance that the radio wave travels in one cycle

A

Wavelength

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9
Q

refers to the physical orientation of the electric field on space

A

Polarization

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10
Q

Types of Polarization

A
  1. Linear
  2. Circular
  3. Elliptical
  4. Random
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11
Q

E field has a particular direction in space may it be horizontal or vertical

A

Linear Polarization

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12
Q

E field is rotating about the axis of the direction of propagation

A

Circular polarization

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13
Q

Similar to circular polarization but E and H are not equal

A

Elliptical polarization

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14
Q

Polarization with no fixed pattern

A

Random Polarization

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15
Q

Line drawn along the direction of propagation of the wave

A

Ray

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16
Q

Surface of constant phase of the wave

A

Wavefront

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16
Q

ratio between electric field intensity and magnetic field intensity.

A

Intrinsic Characteristic Impedance

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17
Q

rate at which energy flows through a unit area of surface in space

A

Power Density

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17
Q

states that power density is inversely proportional to the square of the distance from the source

A

Inverse Square Law

18
Q

The amount of voltage that will be induced by an electromagnetic wave at a specific location

A

Electric Field Intensity or Field Strength

19
Q

The ratio of the speed of radio wave in free space to the speed of radio wave in specific medium

A

Index of Refraction

20
Q

Bending of radio wave as it passes at a medium

A

Refraction

21
Q

An incident wave strikes the boundary of two media and some or all of the incident power does not enter the second material

A

Reflection

22
Q

Types of reflection

A
  1. Diffuse Reflection
  2. Specular Reflection
  3. Rayleigh Criterion
23
Q

Redistribution of energy within a wavefront

A

Diffraction

24
Q

When two waves that left one source and travelled by different paths arrive at a point

A

Interference

25
Q

Modes of Wave Propagation

A
  1. Ground/Surface wave propagation
  2. Sky wave propagation
  3. Space wave/ LOS propagation
26
Q

travels over the surface of the earth

A

Ground wave Propagation

27
Q
  • Aka ionospheric propagation
  • sky waves strike the ionosphere and is reflected back to the ground
A

Sky wave propagation

28
Q

layers of the atmosphere

A

1.Troposphere
2. Stratosphere
3. Ionosphere

29
Q

Lowest layer and is 8-10 miles above sea level

A

Troposphere

30
Q

Also called as isothermal region because of its constant temperature

A

Stratosphere

31
Q

Ionized layer and low-density gas are found

A

ionosphere

32
Q

Layers of the Ionosphere

A
  1. D - Layer
  2. E - Layer
  3. F - Layer
33
Q

-Lowest layer of the ionosphere
- 30 -55 miles above the earth
- ionization begins at sunrise, peaks at local noon and ends at sundown

A

D-Layer

34
Q
  • 55-90 miles above the earth
    -Aids MF
    -ionization peaks at noon
    -aka Kennelly-Heaviside layer
A

E-layer

35
Q
  • 90-240 miles above the Earth
  • divided into two layers during daytime (F1 and F2)
A

F-Layer

36
Q

Highest frequency that will be returned down to earth when beamed vertically upward

A

Critical frequency

37
Q

Highest frequency that will returned down to earth at a given distance at a specific angle

A

Maximum Usable Frequency (MUF)

38
Q

Frequency that gives the most consistent communication

A

Optimum Working Frequency (OWF)

39
Q

apparent height of the ionized layer

A

Virtual Height

40
Q

area that is between the outer limit of the ground wave range and the inner edge of the energy of return from the ionosphere

A

Skip zone

41
Q

Distance between the originating site and the beginning of the atmospheric return

A

Skip distance

42
Q
  • Aka Line of Sight propagation
A

Space Wave propagation

43
Q

refers to the boundary line beyond which direct rays of the radio waves cannot be propagated over the earth’s surface

A

Radio horizon

Communications 4 (4 decks)

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