Electromagnetic Wave Propagation Quiz 1

33 Questions  Settings  For COMMUNICATIONS 3 students

• 1.
Ground-wave communications is most effective in what frequency range?
• A.

300 kHz to 3 MHz

• B.

3 to 30 MHz

• C.

30 to 300 MHz

• D.

above 300 MHz

• 2.
The ionization causes the signal to be
• A.

Diffused

• B.

Absorbed

• C.

refracted

• D.

Reflected

• 3.
The critical frequency at a particular time is 11.6 MHz. What is the MUF for a transmitting station if the required angle of incidence for propagation to a desired destination is 70°?
• A.

12.3 MHz

• B.

33.9 Hz

• C.

33.9 MHz

• D.

12.3 Hz

• 4.
The ionosphere has the greatest effect on signals in what frequency range?
• A.

300 kHz

• B.

3 to 30 MHz

• C.

30 to 300 MHz

• D.

Above 300 MHz

• 5.
The type of radio wave responsible for long-distance communications by multiple skips is the
• A.

ground wave

• B.

direct-wave

• C.

surface wave

• D.

Sky wave

• 6.
Microwave signals propagate by way of the
• A.

direct wave

• B.

Sky wave

• C.

surface wave

• D.

Standing wave

• 7.
Line-of-sight communications is not a factor in which frequency range?
• A.

VHF

• B.

UHF

• C.

HF

• D.

Microwave

• 8.
A microwave-transmitting antenna is 550 ft high. The receiving antenna is 200 ft high. The maximum transmission distance is
• A.

53.2 km

• B.

53.2 ft

• C.

53.2 mi

• D.

53.2 m

• 9.
To increase the transmission distance of a UHF signal, which of the following should be done?
• A.

Increase antenna gain

• B.

Increase antenna height

• C.

Increase transmitter power

• D.

• 10.
_________ is the amount of voltage induced in a wave by an electromagnetic wave.
• A.

• B.

Field strength

• C.

Magnetic induction

• D.

Power density

• 11.
An electromagnetic wave consists of ____________.
• A.

Both electric field and magnetic field

• B.

An electric field only

• C.

A magnetic field only

• D.

Non-magnetic field only

• 12.
If a radio receiver needs 1 nW/m2 of power density to function, how far away from a 1-W point source will it continue to work?
• A.

8.9 km

• B.

8.9 m

• C.

9.8 km

• D.

9.8 m

• 13.
What causes tropospheric ducting of radio waves?
• A.

A very low pressure area

• B.

An aurora to the north

• C.

Lightning between the transmitting and receiving antenna

• D.

A temperature inversion

• 14.
What is a wavefront?
• A.

A voltage pulse in a conductor

• B.

A current pulse in a conductor

• C.

A voltage pulse across a resistor

• D.

A fixed point in an electromagnetic wave

• 15.
• A.

595 nW

• B.

595 pW

• C.

56.9 nW

• D.

56.9 W

• 16.
What causes the ionosphere to absorb radio waves?
• A.

The weather below the ionosphere

• B.

The ionization of the D region

• C.

The presence of the ionized cloud in the E region

• D.

The splitting of the E region

• 17.
Which ionospheric region is closest to the Earth?
• A.

A region

• B.

E Region

• C.

D region

• D.

F region

• 18.
What causes the VHF radio waves to be propagated several hundred miles over oceans?
• A.

An overcast of cirriform clouds

• B.

A high pressure zone

• C.

A polar air mass

• D.

A widespread temperature inversion

• 19.
Microwave and UHF systems have which of the following in common?
• A.

Both provide fade-free communications

• B.

Both are cheaper than HF radio

• C.

They operate on the same frequency band.

• D.

They are both line-of-sight (LOS) systems.

• 20.
• A.

Uses molecules in the Earth’s troposphere to scatter some radio energy back to Earth

• B.

Has a limited capability for data transmission

• C.

Is not widely used commercially

• D.

All of the above

• 21.
Which of the following are electromagnetic?
• A.

• B.

Light

• C.

Gamma rays

• D.

All of the above

• 22.
Sky wave cannot be “heard”
• A.

Close to the transmitter

• B.

Far from the transmitter

• C.

In the silent zone

• D.

In the skip zone

• 23.
• A.

113 kW

• B.

113 W

• C.

131 W

• D.

131 kW

• 24.
Helical antennas are often used for satellite tracking at VHF because of
• A.

Troposcatter

• B.

Ionospheric refraction

• C.

Subrefraction

• D.

• 25.
Diffraction of electromagnetic waves
• A.

is caused by reflections from the ground wave

• B.

arrives only with spherical wavefronts

• C.

Will occur around edge of a sharp obstacle

• 26.
The absorption of radio waves by the atmosphere depends on
• A.

Their frequency

• B.

Their distance from the transmitter

• C.

The polarization of the wave

• D.

The polarization of the atmosphere

• 27.
The characteristic impedance of free space is
• A.

Not known

• B.

50Ω

• C.

infinite

• D.

377Ω

• 28.
The largest frequency that will be returned to the Earth when transmitted vertically under ionospheric conditions is called the
• A.

Critical frequency

• B.

Optimum Working Frequency (OWF)

• C.

Maximum Usable Frequency (MUF)

• D.

Skip zone

• 29.
As electromagnetic waves travel in free space, only one of the following can happen to them:
• A.

Absorption

• B.

Reflection

• C.

Attenuation

• D.

Refraction

• 30.
In a vacuum, the speed of light
• A.

Depends on its constant

• B.

Depends on its wavelength

• C.

Depends on its electric and magnetic field

• D.

Is a universal constant

• 31.
When the magnetic field is perpendicular to the surface of the Earth, what is the polarization of the TEM wave?
• A.

Circular

• B.

Elliptical

• C.

Vertical

• D.

Horizontal

• 32.
What is the period of the solar cycle in which great electrical disturbance will occur?
• A.

Every 11 years

• B.

Every 4 years

• C.

Every 5 years

• D.

Every 10 years

• 33.
Ducting occurs in which region of the atmosphere?
• A.

F2

• B.

Stratosphere

• C.

Troposphere

• D.

Ionosphere

Related Topics