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Core 1 20B > Radar Theory > Flashcards

Radar Theory Flashcards

1
Q

Radar Polarization

A

The orientation of the electrical field

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2
Q

Frequency

A

The number of cycles that the RF energy completes per second

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3
Q

Electro Magnetic Radiation

A

Synchronized oscillations (sinusoidal waves) or electric and magnetic fields that propagate through a vacuum at the speed of light

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4
Q

Wavelength

A

The physical distance of one complete wave

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5
Q

Radar Beamwidth

A

The angular size of the main beam, normally expressed in degrees.

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6
Q

Phase Differences

A

The degree to which individual cycles of a wave coincide with those of a reference wave of the same frequency.

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7
Q

List the 7 types of electro magnetic radiation in order of decreasing wavelengths

A

1: Extremely low-frequency waves
2: Radio waves
3: Microwaves
4: Infrared radiation
5: Visible light
6: Ultraviolet radiation
7: X-rays & gamma rays

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8
Q

How is frequency measured?

A

Hz

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9
Q

A radars operating frequency impacts what performance parameters of the radar’s performance?

A

Atmospheric attenuation
physical size
transmitted power
doppler considerations

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10
Q

List characteristics of the lower frequency radar

A
  • Long wavelength
  • Large antenna
  • Components able to generate high transmit power
  • Low atmospheric attenuation
  • Good long-range detection capability but poor precision
  • Best for long-range EW radars
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11
Q

List characteristics of the higher frequency radar

A
  • Shorter wavelengths
  • Smaller antenna
  • Smaller components for less power
  • Shorter detection range
  • High precision
  • Atmospheric attenuation more of a problem
  • Used for fire-control radars for fighters, SAMs and ADA
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12
Q

The strength of a radar signal hitting a target is approximately proportional to what parameter?

A

1/(range to the target)squared

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13
Q

For a fixed antenna size a radar operating at a higher frequency than another will the beamwidth be narrower or wider?

A

narrower

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14
Q

For a fixed operating frequency which radar will have a narrower beamwidth; a large antenna or a small antenna?

A

a large antenna

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15
Q

T or F: Angular (azimuth and elevation) resolution is a function of beamwidth and range to the targets.

A

True

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16
Q

An electronically scanned array atenna differs in what two fundamental ways form a mechanically scanned array radar?

  • The antenna is mounted in a fixed position
  • The antenna is NOT mounted in a fixed position
  • The radar beam is steered by individually controlling the phase of the radio waves transmitted and received by each radiating element.
A
  • The antenna is mounted in a fixed position
  • The radar beam is steered by individually controlling the phase of the radio waves transmitted and received by each radiating element.
17
Q

What are the advantages of passive and active electronically scanned array radars?

A
  • High reliability.
  • Extreme beam agility.
  • Facilitate radar cross-section reduction.
18
Q

Define radar range resolution

A

A radars ability to resolve multiple targets in range

19
Q

Range resolution is based on what parameter?

A

Pulse width (t)

20
Q

Define radar resolution cell

A

The smallest amount of three-dimensional air space in which a radar cannot distinguish between multiple targets

21
Q

Pulse repetition frequency is?

A

The rate at which pulses are transmitted

22
Q

Pulsed Radar (advantage or disadvantage):

Only one antenna required

23
Q

Pulsed Radar (advantage or disadvantage):

Lower average output power limits detection range

A

Disadvantage

24
Q

Pulsed Radar (advantage or disadvantage):

Cannot filter out ground clutter without increased processing

A

Disadvantage

25
Q

Pulsed Radar (advantage or disadvantage):

Good range accuracy

26
Q

Pulsed Radar (advantage or disadvantage):

Not very accurate in velocity measurement

A

Disadvantage

27
Q

Pulsed Radar (advantage or disadvantage):

Simple electronics

28
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Simple

29
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

No range information

A

Disadvantage

30
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Good against high aspect angle targets

31
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Poor against beam and stern targets

A

Disadvantage

32
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Very accurate velocity measurement

33
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Two antennas required

A

Disadvantage

34
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

High average output power increases detection range

35
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Can filter out ground clutter

36
Q

Continuous wave/ Doppler Radar
(advantage or disadvantage)

Susceptible to doppler notch

A

Disadvantage

Core 1 20B (5 decks)

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