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Wireless Technologies > RF Theory > Flashcards

RF Theory Flashcards

1
Q

Gain

A

Is the amplification of a signal which can compensate for losses. It is possible to adjust the gain settings in both the transmitter and receiver to produce the correct output signal strength

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2
Q

What are the three components of Radio Frequency Waves?

A

Amplitude, Frequency, Phase

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3
Q

Phase

A

Where the phase is at any given moment.

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4
Q

Wavelength

A

The distance between a given point on one cycle and the same point on the next cycle.

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5
Q

Impedance

A

Describes the resistance a circuit presents to alternating current and is measured in ohms.

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6
Q

Refraction

A

Is the changing or bending of waves where the boundary of one medium meets another.

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7
Q

Attenuation

A

Is defined in physics as the decrease in a property, as energy, per unit of a wave of a beam of particles, which increases as a result of absorption, scattering, spreading in three dimensions, etc.

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8
Q

FM Frequency modulation

A

If this input signal is added to the pure carrier wave, it will thereby change the frequency of the carrier wave. In that way, users can use changes of frequency to carry speech information.

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9
Q

Velocity

A

Signals speed in a particular direction.

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10
Q

Inter-Modulation Interference

A

Is produced by mixing together several different signals, generally from different radio systems.

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11
Q

What are the four main types of Interference?

A

Co-Channel Interference, Adjacent Channel Interference, Inter-modulation interference, Unintended Electromagnetic Radiation

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12
Q

Unintended Electromagnetic Radiation

A

This is produced from non-radio systems like power lines, transformers, solar flares, etc.

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13
Q

Carrier Wave

A

Is a high frequency signal which has a specific amplitude, frequency, and phase levels, but it does not hold any data.

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14
Q

Reflection

A

Occurs when a wave encounters an obstruction and is not absorbed

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15
Q

Frequency (RF)

A

The number of waves passing through in a given second

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16
Q

Amplitude

A

The height of the wave (or power given to make the signal)

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17
Q

What are the three components of Radio Frequency Waves?

A

Amplitude, Frequency, Phase

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18
Q

AM Amplification modulation

A

The fluctuations in power (amplitude) of the wave carries the data.

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19
Q

Modulating Signal

A

This signal is what holds the message or traffic. Signals are sent through what is called a modulator to attach onto a signal and is then sent out across the airwaves to a destination.

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20
Q

Active Gain

A

Uses an RF amplifier to increase the signal strength. The amplifier is placed in path between the AP and antenna or between the radio and antenna.

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21
Q

Diffraction

A

Is when radio signals encounter an obstacle they tend to travel around the obstacle. This means that even if the direct path of a signal is blocked, the “new” wave will continue to spread out in 3 dimensions, even though there is not Line-Of-Sight (LOS).

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22
Q

Voltage Standing Wave Ratio (VSWR)

A

describes the ratio of mismatch. If this is high enough, the standing wave can cause signal distortion and damage the transmitter.

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23
Q

Passive Gain

A

Uses no extra amplification and relies fully on the directionality of the antenna for increased RF energy in a desired direction.

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24
Q

What are the 3 components to Electromagnetic Waves?

A

Frequency, Wavelength, Velocity

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25
Q

Adjacent Channel Frequency

A

Occurs when channels are on a different set of frequencies but are too close together

26
Q

Absorption

A

Occurs when a radio wave hits an object, and some of its energy is absorbed rather than redirected.

27
Q

Multi-Path

A

Occurs when a coherent signal takes multiple paths to a destination, and arrives out of phase.
Multi-path fading is generally destructive to an RF signal

28
Q

Attenuation is generally caused by what three things?

A

Frequency/Noise, Physical Surroundings, Distance

29
Q

Co-Channel Interference

A

Signals are on the same Frequency

30
Q

Frequency (EM)

A

The number of times that a particular point on the wave moves up and down in a given time (normally measured in seconds).

31
Q

Modulation

A

Is process by which voice, music, and other “intelligence” is added to the radio waves produced by a transmitter.

32
Q

Is the amplification of a signal which can compensate for losses. It is possible to adjust the gain settings in both the transmitter and receiver to produce the correct output signal strength

A

Gain

33
Q

Amplitude, Frequency, Phase

A

What are the three components of Radio Frequency Waves?

34
Q

Where the phase is at any given moment.

A

Phase

35
Q

The distance between a given point on one cycle and the same point on the next cycle.

A

Wavelength

36
Q

Describes the resistance a circuit presents to alternating current and is measured in ohms.

A

Impedance

37
Q

Is the changing or bending of waves where the boundary of one medium meets another.

A

Refraction

38
Q

Is defined in physics as the decrease in a property, as energy, per unit of a wave of a beam of particles, which increases as a result of absorption, scattering, spreading in three dimensions, etc.

A

Attenuation

39
Q

If this input signal is added to the pure carrier wave, it will thereby change the frequency of the carrier wave. In that way, users can use changes of frequency to carry speech information.

A

FM Frequency modulation

40
Q

Signals speed in a particular direction.

A

Velocity

41
Q

Is produced by mixing together several different signals, generally from different radio systems.

A

Inter-Modulation Interference

42
Q

Co-Channel Interference, Adjacent Channel Interference, Inter-modulation interference, Unintended Electromagnetic Radiation

A

What are the four main types of Interference?

43
Q

This is produced from non-radio systems like power lines, transformers, solar flares, etc.

A

Unintended Electromagnetic Radiation

44
Q

Is a high frequency signal which has a specific amplitude, frequency, and phase levels, but it does not hold any data.

A

Carrier Wave

45
Q

Occurs when a wave encounters an obstruction and is not absorbed

A

Reflection

46
Q

The number of waves passing through in a given second

A

Frequency (RF)

47
Q

The height of the wave (or power given to make the signal)

A

Amplitude

48
Q

Amplitude, Frequency, Phase

A

What are the three components of Radio Frequency Waves?

49
Q

The fluctuations in power (amplitude) of the wave carries the data.

A

AM Amplification modulation

50
Q

This signal is what holds the message or traffic. Signals are sent through what is called a modulator to attach onto a signal and is then sent out across the airwaves to a destination.

A

Modulating Signal

51
Q

Uses an RF amplifier to increase the signal strength. The amplifier is placed in path between the AP and antenna or between the radio and antenna.

A

Active Gain

52
Q

Is when radio signals encounter an obstacle they tend to travel around the obstacle. This means that even if the direct path of a signal is blocked, the “new” wave will continue to spread out in 3 dimensions, even though there is not Line-Of-Sight (LOS).

A

Diffraction

53
Q

describes the ratio of mismatch. If this is high enough, the standing wave can cause signal distortion and damage the transmitter.

A

Voltage Standing Wave Ratio (VSWR)

54
Q

Uses no extra amplification and relies fully on the directionality of the antenna for increased RF energy in a desired direction.

A

Passive Gain

55
Q

Frequency, Wavelength, Velocity

A

What are the 3 components to Electromagnetic Waves?

56
Q

Occurs when channels are on a different set of frequencies but are too close together

A

Adjacent Channel Frequency

57
Q

Occurs when a radio wave hits an object, and some of its energy is absorbed rather than redirected.

A

Absorption

58
Q

Occurs when a coherent signal takes multiple paths to a destination, and arrives out of phase.
Multi-path fading is generally destructive to an RF signal

A

Multi-Path

59
Q

Frequency/Noise, Physical Surroundings, Distance

A

Attenuation is generally caused by what three things?

60
Q

Signals are on the same Frequency

A

Co-Channel Interference

61
Q

The number of times that a particular point on the wave moves up and down in a given time (normally measured in seconds).

A

Frequency (EM)

62
Q

Is process by which voice, music, and other “intelligence” is added to the radio waves produced by a transmitter.

A

Modulation

Wireless Technologies (16 decks)

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