REM C LVL 2

Question 1

The characteristic impedance of a
parallel wire transmission line does not
depend on the:

A. radius of the conductors
B. dielectric
C. velocity of energy on the line
D. centre to centre distance between
conductors

Answer 1

C. velocity of energy on the line

Physical dimensions (radius and centre
to centre distance) and dielectric
influence Characteristic Impedance. The speed at which waves travel on the line (velocity) is another characteristic altogether.

Question 2

In an HF station, which component is temporarily connected in the tuning process?

A. SWR bridge
B. Low pass filter
C. Dummy load
D. Antenna tuner

Answer 2

C. Dummy load

The ‘Dummy Load’ (a resistor with a
high power rating) dissipates RF energy as heat without radiating the RF on the air. Permits tests or adjustments without causing interference to other stations. The tuning process’ refers to a
manual procedure necessary for
equipment with vacuum tube final
Power Amplifiers where variable
capacitors needed to be adjusted with
each frequency change.

Question 3

The skin effect causes the current to
flow

A. At the center of the conductor
B. near the surface of the conductor
C. uniformly through the conductor
D. Through the central core of the conductor

Answer 3

B. near the surface of the conductor

Question 4

For transmission-line load matching
over a range of frequencies, it is best to
use a ____

A. balun
B. double stub
C. broadband directional coupler
D. single stub of adjustable position

Answer 4

B. double stub

Double stub is used for frequencies
above microwave frequencies.
Single stub is used for frequencies
below microwave range.

Question 5

A transmission line differs from an
ordinary circuit or network in
communications or signaling devices in one very important way. That important aspect is:

A. capacitive reactance
B. propagation delay
C. inductive reactance
D. resistance

Answer 5

B. propagation delay

Radio signals propagate (travel) slower
in a transmission line than they do in
space.’Propagation Delay’ is specific to
transmission lines. Resistance and
reactance can be found in many other
components or circuits.

Question 6

What factors determine the
characteristic impedance of a parallel-
conductor antenna feed line?

A. The frequency of the signal and the length
of the line
B. The distance between the centres of the
conductors and the length of the line
C. The radius of the conductors and the
frequency of the signal
D. The distance between the centres of the conductors and the radius of the conductors

Answer 6

D. The distance between the centres of the conductors and the radius of the conductors

Physical dimensions (radius and centre
to centre distance) influence
Characteristic Impedance. It is
independent of line length or operating
frequency.

Question 7

Why should you use only good quality
coaxial cable and connectors for a UHF
antenna system?

A. To keep television interference high
B. To keep the power going to your antenna
system from getting too high
C. To keep the standing wave ratio of your
antenna system high
D. To keep RF loss low

Answer 7

D. To keep RF loss low

Losses in transmission lines increase with length and operating frequencies.At Ultra High Frequencies (UHF, 300
MHz to 3000 MHz), keeping losses low
is paramount.

Question 8

What factors determine the
characteristic impedance of a coaxial
antenna feed line?

A. The diameter of the braid and the
frequency of the signal
B. The diameter of the braid and the length of
the line
C. The ratio of the diameter of the inner
conductor to the diameter of the braid
D. The frequency of the signal and the length
of the line

Answer 8

C. The ratio of the diameter of the inner
conductor to the diameter of the braid

The Characteristic Impedance of coaxial
cable is determined by the ratio of the
outer conductor to the inner conductor.
It is independent of line length or
operating frequency.

Question 9

To reduce harmonic output from a
transmitter, you would put a
____ in the transmission line as
close to the transmitter as possible.

A. high pass filter
B. wave trap
C. band reject filter
D. low pass filter

Answer 9

D. low pass filter

HARMONIC. ‘Harmonic Radiation’ (integer multiples of the operating frequency). A ‘Low- Pass’ filter with a cutoff frequency of 30 MHz helps curb harmonics out of an HF transmitter. A ‘High-Pass’ filter is used on a TV receiver to prevent overload
from an HF transceiver.

Question 10

A flexible coaxial line contains:

A. four or more conductors running parallel
B. only one conductor
C. two parallel conductors separated by
spacers
D. braid and insulation around a central
conductor

Answer 10

D. braid and insulation around a central
conductor

Coaxial: two concentric conductors, an inner conductor, a dielectric (insulator)and an outer conductor (braided or solid). “Two parallel conductors separated by spacers” are also known as ‘open wire line’ or ‘ladder line’.

Question 11

If an antenna is correctly matched to a transmitter, the length of transmission line:

A. must be an odd number of quarter-wave
B. will have no effect on the matching
C. must be an even number of half-waves
D. must be a full wavelength long

Answer 11

B. will have no effect on the matching

IF a mismatch is present at the end of the transmission lines, certain lengths may introduce an ‘impedance transformation’ effect. With a correctly matched antenna, line length is
immaterial except for line losses if the line is unnecessarily long.

Question 12

Why does coaxial cable make a good
antenna feed line?

A. It can be used near metal objects, and its
impedance is higher than that of most
amateur antennas
B. It is weatherproof, and its impedance
matches most amateur antennas
C. You can make it at home, and its
impedance matches most amateur
antennas
D. It is weatherproof, and its impedance is
higher than that of most amateur antennas

Answer 12

B. It is weatherproof, and its impedance
matches most amateur antennas

Parallel lines generally have
Characteristic Impedances in the range of 300 to 600 ohms. Common coaxial cable have Characteristic Impedances
of 50 or 75 ohms. Such an impedance is
a direct match to transmitters and
common antennas.

Question 13

How does the bandwidth of a
transmitted signal affect selective
fading?

A. It is the same for both wide and narrow
bandwidths
B. It is more pronounced at wide
bandwidths
C. It is more pronounced at narrow
bandwidths
D. Only the receiver bandwidth determines
the selective fading effect

Answer 13

B. It is more pronounced at wide
bandwidths

Parts of a wave arriving with difference
in phases (Selective Fading) cause a
fluctuation in the perceived signal.
Signals with large bandwidths are more susceptible to Selective Fading. SSB is less affected.

Question 14

The optimum working frequency
provides the best long range HF
communication. Compared with the
maximum usable frequency (MUF), it is
usually:

A. half the MUF
B. slightly lower
C. double the MUF
D. slightly higher

Answer 14

B. slightly lower

As Maximum Usable Frequency (MUF) is the highest frequency usable for sky wave propagation between two points on the globe, using lower frequencies are also refracted back to Earth. In fact the Optimum Working Frequency is somewhat lower than the MUF [85%]. Note that frequencies below the MUF are more subject to absorption and noise so a lower limit does exist.Refraction of a given signal by the ionosphere is dependent on the frequency, the level of ionization and the angle of entry into a layer

Question 15

The source, detector, and medium are
all necessary for

A. Wave motion and Wave propagation
B. Wave motion
C. Wave propagation
D. Electromagnetic waves

Answer 15

A. Wave motion and Wave propagation

The source, detector, and medium are
all necessary for wave motion and wave propagation (except for electromagnetic waves which require no medium).

Question 16

That portion of the radiation kept close to the earth’s surface due to bending in the atmosphere is called the:

A. ionospheric wave
B. tropospheric wave
C. ground wave
D. inverted wave

Answer 16

B. tropospheric wave

BENDING. Tropospheric bending :
refraction occurs when a wave travels through masses of differing densities(humidity content) in the troposphere.The wave travels further rather than escape right away into space.

Question 17

What effect does the D region of the
ionosphere have on lower frequency HF
signals in the daytime?

A. It bends the radio waves out into space
B. It has little or no effect on 80-metre radio
waves
C. It refracts the radio waves back to earth
D. It absorbs the signals

Answer 17

D. It absorbs the signals

The D layer, closest of the layers, is
fairly dense. Once ionized during
daylight hours, it ABSORBS lower
frequencies (i.e., 160m and 80m).

Question 18

The attenuation that a surface wave
undergoes because of induced voltage depends on the electrical properties of the terrain over which the wave travels.The best type of surface is one that has good electrical conductivity. Which one of this surface type has good
conductivity?

A. Jungle
B. Sea water
C. Rocky terrain
D. Desert

Answer 18

B. Sea water

The attenuation that a surface wave
undergoes because of induced voltage depends on the electrical properties of the terrain over which the wave travels.The best type of surface is one that has good electrical conductivity. The better the conductivity, the less the
attenuation.

Question 19

An X band radar operates in which
frequency band?

A. 4 - 8GHz
B. 8 -12 GHz
C. 1- 2GHz
D. 2 - 4 GHz

Answer 19

B. 8 -12 GHz

Question 20

Transmission from the earth to the
satellite is called ____

A. up print
B. footlink
C. uplink
D. downlink

Answer 20

C. uplink

Question 21

What usually happens to radio waves with frequencies below the maximum usable frequency (MUF) when they are sent into the ionosphere?

A. They are changed to a frequency above the
MUF
B. They are bent back to the earth
C. They pass through the ionosphere
D. They are completely absorbed by the
ionosphere

Answer 21

B. They are bent back to the earth

As Maximum Usable Frequency (MUF) is the highest frequency usable for sky wave propagation between two points on the globe, using lower frequencies
are also refracted back to Earth. In fact,
the Optimum Working Frequency is
somewhat lower than the MUF [85%].Note that frequencies below the MUF are more subject to absorption and noise so a lower limit does exist. Refraction of a given signal by the ionosphere is dependent on the frequency, the level of ionization and the
angle of entry into a layer.

Question 22

During summer daytime, which bands
are the most difficult for
communications beyond ground wave?

A. 160 and 80 metres
B. 40 metres
C. 30 metres
D. 20 metres

Answer 22

A. 160 and 80 metres

During the summer, two problems can
affect 160m and 80m: static from
lightning (thunderstorms) and D-layer absorption. The D layer, closest of the layers, is fairly dense. Once ionized
during daylight hours, it ABSORBS lower
frequencies (i.e., 160m and 80m).

Question 23

At what point in the solar cycle does the
20-metre band usually support
worldwide propagation during daylight
hours?

A. Only at the maximum point of the solar
cycle
B. Only at the minimum point of the solar
cycle
C. At any point in the solar cycle
D. At the summer solstice

Answer 23

C. At any point in the solar cycle

During solar peaks and solar lows, the
20m band (14.0 MHz to 14.35 MHz)
usually support worldwide
communications during the day.

Question 24

The primary path of the space wave is

A. None of these choices
B. Direct path
C. Refracted path
D. Ground reflected path

Answer 24

B. Direct path

Question 25

Which ionospheric region most affects sky-wave propagation on the 6 metre band? A. The F1 region B. The E region C. The D region D. The F2 region

Answer 25

B. The E region At 50 to 54 MHz, the 6m band normally escapes into space. However, 'Sporadic E'(intense but temporary ionization of patches in the upper regions of the E layer ) can provide refraction paths for 6m.

Question 26

Where in the ionosphere does auroral activity occur? A. At F-region height B. In the equatorial band C. At E-region height D. At D-region height

Answer 26

C. At E-region height AURORA. The arrival of high-energy particles from the Sun (e.g., after a solar flare) disturb the Earth's magnetic field (a geomagnetic storm). The resulting unusual ionization of gases in the E layer above the poles produce the visual display known as 'aurora' ("Northern Lights"). Pointing antennas at the aurora front permit oblique paths to distant stations.

Question 27

At what frequencies does the surface wave is impractical for long distance transmissions? A. 2-3 MHz B. 2 MHz C. Below 2 MHz D. Above 2 MHz

Answer 27

D. Above 2 MHz Another major factor in the attenuation of surface waves is frequency. The higher the frequency of a radio wave, the shorter its wavelength will be. These high frequencies, with their shorter wavelengths, are not normally diffracted but are absorbed by the Earth at points relatively close to the transmitting site.You can assume, therefore that as the frequency of a surface wave is increased, the more rapidly the surface wave will be absorbed, or attenuated, by the Earth. Because of this loss by attenuation, the surface wave is impractical for long-distance transmissions at frequencies above 2 MHz

Question 28

When is the ionosphere most ionized? A. Midnight B. Midday C. Dusk D. Dawn

Answer 28

B. Midday MOST. At midday, with the Sun shining directly at the ionosphere, ionization is most intense. As the Sun sets and throughout the night, ions recombine (how quickly depending on the density of a given layer) so that ionization is minimum right before dawn (sunrise).

Question 29

How long is an average sunspot cycle? A. 7 years B. 5 years C. 11 years D. 17 years

Answer 29

C. 11 years AVERAGE. The duration of the solar cycles varies from 7 to 17 years but the AVERAGE is 11 YEARS

Question 30

What does horizontal wave polarization mean? A. The electric lines of force of a radio wave are perpendicular to the earth's surface B. The electric and magnetic lines of force of a radio wave are perpendicular to the earth's surface C. The electric lines of force of a radio wave are parallel to the earth's surface D. The magnetic lines of force of a radio wave are parallel to the earth's surface

Answer 30

C. The electric lines of force of a radio wave are parallel to the earth's surface An electromagnetic wave comprises an electrical field and a magnetic field. Wave Polarization describes the position of the ELECTRIC field with respect to the earth's surface. On a dipole antenna or on the 'driven' element of a Yagi, the electric field is developed between the tips of the radiating element.

Question 31

What causes selective fading? A. Time differences between the receiving and transmitting stations B. Large changes in the height of the ionosphere at the receiving station ordinarily occurring shortly before sunrise and sunset C. Small changes in beam heading at the receiving station D. Phase differences between radio wave components of the same transmission, as experienced at the receiving station

Answer 31

D. Phase differences between radio wave components of the same transmission, as experienced at the receiving station Parts of a wave arriving with difference in phases (Selective Fading) cause a fluctuation in the perceived signal. Signals with large bandwidths are more susceptible to Selective Fading. SSB is less affected.

Question 32

Which emission modes are best for auroral propagation? A. FM and CW B. CW and SSB C. SSB and FM D. RTTY and AM

Answer 32

B. CW and SSB The unstable front of the aurora and ensuing scattering of the radio wave make for distorted signals, only the smaller bandwidth signals are usable

Question 33

Why are HF scatter signals usually weak? A. Propagation through ground waves absorbs most of the signal energy B. Only a small part of the signal energy is scattered into the skip zone C. The F region of the ionosphere absorbs most of the signal energy D. Auroral activity absorbs most of the signal energy

Answer 33

B. Only a small part of the signal energy is scattered into the skip zone SCATTER, WEAK. Signals propagated via 'HF Scatter' have a characteristic weak and distorted (hollow, echo-like) sound. The distortion is caused by multi-path effects. Unlike simple refraction, where the entire signal changes direction, scattering splits the signal in many directions (thus explaining the weakness).

Question 34

This field is said to provide no part in the transmission of electromagnetic energy through free space. However, without the presence of this field, there would be no energy radiated. A. Induction field B. Magnetic field C. Electric field D. Radiation field

Answer 34

A. Induction field INDUCTION FIELD the electromagnetic field produced about an antenna when current and voltage are present on the same antenna. It exists close to the conductor carrying the current. The field associated with the energy stored in the antenna. This field is said to provide no part in the transmission of electromagnetic energy through free space. However, without the presence of this field, there would be no energy radiated.

Question 35

As a surface wave passes over the ground, the wave induces a voltage in the earth. The induced voltage takes energy away from the surface wave, thereby weakening, or attenuating, the wave as it moves away from the transmitting antenna. To reduce the attenuation, the amount of induced voltage must be reduced. This is done by using _____ waves that minimize the extent to which the electric field of the wave is in contact with the Earth. A. Circularly polarized B. Horizontally polarized C. Vertically polarized D. Parallel

Answer 35

C. Vertically polarized

Question 36

When is the ionosphere least ionized? A. Just after dusk B. Just after noon C. Shortly before dawn D. Shortly before midnight

Answer 36

C. Shortly before dawn LEAST. At midday, with the Sun shining directly at the ionosphere, ionization is most intense. As the Sun sets and throughout the night, ions recombine(how quickly depending on the density of a given layer) so that ionization is minimum right before dawn (sunrise).

Question 37

What makes HF scatter signals often sound distorted? A. Energy scattered into the skip zone through several radio-wave paths B. Propagation through ground waves that absorb much of the signal C. Auroral activity and changes in the earth's magnetic field D. The state of the E-region at the point of refraction

Answer 37

A. Energy scattered into the skip zone through several radio-wave paths SCATTER, DISTORTED. Signals propagated via 'HF Scatter' have a characteristic weak and distorted (hollow, echo-like) sound. The distortion is caused by multi-path effects. Unlike simple refraction, where the entire signal changes direction, scattering splits the signal in many directions (thus explaining the weakness).

Question 38

Rayleigh scatter is most severe A. in light with a short wavelength B. at sunset C. in low frequency light D. in blue light on Earth and black light on the moon

Answer 38

A. in light with a short wavelength Rayleigh scattering, named after the nineteenth-century British physicist Lord Rayleigh, is the predominantly elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.

Question 39

What kind of propagation would best be used by two stations within each other's skip zone on a certain frequency? A. Sky-wave B. Scatter-mode C. Ducting D. Ground-wave

Answer 39

B. Scatter-mode "Beyond Ground Wave and too close for normal Sky Wave" is the 'Skip Zone, a zone of silence. The only explanation for propagation into the Skip Zone is HF SCATTER.

Question 40

How does the range of sky-wave propagation compare to ground-wave propagation? A. It is about the same B. It depends on the weather C. It is much shorter D. It is much longer

Answer 40

D. It is much longer Ground Wave propagation present on long wavelengths (e.g., 160m and 80m) is of the order of 200 km. One hop via the E layer of the ionosphere can reach to 2000 km. One hop via the F2 layer can reach to 4000 km.

Question 41

What happens to signals higher in frequency than the critical frequency? A. They pass through the ionosphere B. They are absorbed by the ionosphere C. They are reflected back to their source D. Their frequency is changed by the ionosphere to be below the maximum usable frequency

Answer 41

A. They pass through the ionosphere The 'Critical Frequency' is a measurement of the highest frequency which will be refracted back to Earth when sent straight up at a given time Above the Critical Frequency, the wave escapes into space. How high the Critical Frequency is, relates to the ionization level.

Question 42

In the northern hemisphere, in which direction should a directional antenna be pointed to take maximum advantage of auroral propagation? A. East B. South C. West D. North

Answer 42

D. North AURORA. The arrival of high-energy particles from the Sun (e.g., after a solar flare) disturb the Earth's magnetic field (a geomagnetic storm). The resulting unusual ionization of gases in the E layer above the poles produce the visual display known as 'aurora' ("Northern Lights"). Pointing antennas at the aurora front permit oblique paths to distant stations.

Question 43

What does vertical wave polarization mean? A. The electric lines of force of a radio wave are parallel to the earth's surface B. The electric and magnetic lines of force of a radio wave are parallel to the earth's surface C. The magnetic lines of force of a radio wave are perpendicular to the earth's surface D. The electric lines of force of a radio wave are perpendicular to the earth's surface

Answer 43

D. The electric lines of force of a radio wave are perpendicular to the earth's surface An electromagnetic wave comprises an electrical field and a magnetic field. Wave Polarization describes the position of the ELECTRIC field with respect to the earth's surface. On a dipole antenna or on the 'driven' element of a Yagi, the electric field is developed between the tips of the radiating element.

Question 44

Which region of the ionosphere is the least useful for long distance radio- wave propagation? A. The E region B. The D region C. The F1 region D. The F2 region

Answer 44

B. The D region The D layer, closest of the layers, is fairly dense. Once ionized during daylight hours, it ABSORBS lower frequencies (i.e., 160m and 80m).

Question 45

If the incident angle of the radio wave energy is perpendicular to a DULL surface, more of the incident energy is A. Reflected B. Regenerated C. Transmitted D. Absorbed by the surface

Answer 45

D. Absorbed by the surface

Question 46

What is a sporadic-E condition? A. Partial tropospheric ducting at E-region height B. Patches of dense ionization at E-region height C. Variations in E-region height caused by sunspot variations D. A brief decrease in VHF signals caused by sunspot variations

Answer 46

B. Patches of dense ionization at E-region height At 50 to 54 MHz, the 6m band normally escapes into space. However, 'Sporadic E' (intense but temporary ionization of patches in the upper regions of the E layer ) can provide refraction paths for 6m.

Question 47

What influences all radiocommunication beyond ground-wave or line-of-sight ranges? A. The F2 region of the ionosphere B. The F1 region of the ionosphere C. Solar activity D. Lunar tidal effects

Answer 47

C. Solar activity Because the Sun affects the ionosphere and the troposphere (e.g., temperature inversions), it can be said that it has an influence on all radiocommunications.

Question 48

What type of solar radiation is most responsible for ionization in the outer atmosphere? A. Thermal B. lonized particle C. Ultraviolet D. Microwave

Answer 48

C. Ultraviolet Ultraviolet (UV) radiation and particles emanating from the Sun breaks down molecules in the ionosphere to form charged ions.

Question 49

What is a characteristic of HF scatter signals? A. Reversed sidebands B. Reversed modulation C. A wavering sound D. High intelligibility

Answer 49

C. A wavering sound SCATTER, WAVERING. Signals propagated via 'HF Scatter' have a characteristic weak and distorted (hollow, echo-like) sound. The distortion is caused by multi-path effects. Unlike simple refraction, where the entire signal changes direction, scattering splits the signal in many directions (thus explaining the weakness).

Question 50

Communication on the 80 metre band is generally most difficult during: A. daytime in winter B. evening in winter C. evening in summer D. daytime in summer

Answer 50

D. daytime in summer During the summer, two problems can affect 160m and 80m: static from lightning (thunderstorms) and D-layer absorption. The D layer, closest of the layers, is fairly dense. Once ionized during daylight hours, it ABSORBS lower frequencies (i.e., 160m and 80m).

Question 51

A low pass filter in an HF station is most effective when connected: A. as close as possible to the antenna B. as close as possible to the linear amplifier output C. as close as possible to the antenna tuner output D. as close as possible to the linear amplifier input

Answer 51

B. as close as possible to the linear amplifier output A 'Low-Pass' filter serves to reduce 'Harmonics' which can be generated in overdriven, improperly adjusted or malfunctioning AMPLIFIER stages, either the actual Power Amplifier in a transmitter or an external Linear Power Amplifier. Consequently, it should be inserted as close as possible to the transceiver or amplifier if one is used. The HF Station block diagram begins with: Transceiver, Linear Amplifier, Low- Pass Filter, SWR Bridge, Antenna Switch...

Question 52

Compared with a horizontal antenna, a vertical antenna will receive a vertically polarized radio wave: A. without any comparative difference B. at greater strength C. if the antenna changes the polarization D. at weaker strength

Answer 52

B. at greater strength On 'line of sight' propagation (common at Very High Frequencies) and with Ground Wave propagation (common at the low end of High Frequencies), a significant loss is incurred if the antennas on both extremities do NOT have the same polarization.

Question 53

At the ends of a half-wave antenna, what values of current and voltage exist compared to the remainder of the antenna? A. minimum voltage and minimum current B. minimum voltage and maximum current C. maximum voltage and minimum current D. equal voltage and current

Answer 53

C. maximum voltage and minimum current

Question 54

Approximately how much gain does a half-wave dipole have over an isotropic radiator? A. 2.1 dB B. 3.0 dB C. 6.0 dB D. 1.5 dB

Answer 54

A. 2.1 dB An 'isotropic radiator' radiates equally well in ALL directions (radiation pattern is a 'sphere). A dipole in free space has a radiation pattern similar to a donut (maximum radiation broadside from the antenna, none towards the ends). This concentration of radiation produce a gain of 2.1 dB over an isotropic antenna.

Question 55

Moving the feed point of a multi- element quad antenna from a side parallel to the ground to a side perpendicular to the ground will have what effect? A. It will significantly increase the antenna feed point impedance B. It will change the antenna polarization from horizontal to vertical C. It will change the antenna polarization from vertical to horizontal D. It will significantly decrease the antenna feed point impedance

Answer 55

B. It will change the antenna polarization from horizontal to vertical In your head, squish the quad from the top down, it now looks like a Folded Dipole. If the Folded dipole is horizontal, it is polarized horizontally. Flip it 90 degrees and it is now has a vertical polarization.

Question 56

A metal wrapped around the parabolic antenna aperture to eliminate sidelobes interfering nearby stations is called A. shroud B. bass drum C. shield D. radome

Answer 56

A. shroud

Question 57

Compared to a dipole antenna, what are the directional radiation characteristics of a cubical quad antenna? A. The quad has more directivity in the horizontal plane but less directivity in the vertical plane B. The quad has more directivity in both horizontal and vertical planes C. The quad has less directivity in the horizontal plane but more directivity in the vertical plane D. The quad has less directivity in both horizontal and vertical planes

Answer 57

B. The quad has more directivity in both horizontal and vertical planes A quad with its four-sided architecture focuses energy in the vertical (up and down) AND horizontal (left to right) planes.

Question 58

In a Yagi-Uda 3 element directional antenna, the ____ is primarily for mechanical purposes. A. driven element B. director C. boom D. reflector

Answer 58

C. boom The 'boom' supports the elements of the Yagi.

Question 59

Of the components in an HF station,which component would be used to match impedances between the transceiver and antenna? A. Antenna tuner B. Dummy load C. Antenna switch D. SWR bridge

Answer 59

A. Antenna tuner The 'Antenna Tuner' provides variable impedance transformation: it can adapt the impedance of the antenna system (which changes with antenna dimensions and operating frequency) to the design impedance of the transceiver. The 'Antenna Tuner' permits using an antenna on a frequency or band other than the one for which it was designed.

Question 60

Which of the following is an example of a traveling wave antenna? A. rhombic B. yagi-uda C. discone D. log-periodic

Answer 60

A. rhombic Log-periodic antenna is a special version of driven array which has a wide bandwidth. The lengths of the driven element vary from long to short and are related logarithmically.

Question 61

A dipole antenna will emit a vertically polarized wave if it is: A. too near to the ground B. parallel with the ground C. fed with the correct type of RF D. mounted vertically

Answer 61

D. mounted vertically An electromagnetic wave comprises an electrical field and a magnetic field. Wave Polarization describes the position of the ELECTRIC field with respect to the earth's surface. On a dipole antenna or on the 'driven' element of a Yagi, the electric field is developed between the tips of the radiating element.

Question 62

Using a small reflector to beam waves to the larger parabolic reflector is known as A. cassegrain feed B. horn feed C. focal feed D. coax feed

Answer 62

A. cassegrain feed Horn feed - the primary antenna is a small horn antenna rather than a simple dipole or dipole array. The horn is simply a flared piece of waveguide material that is placed at the focus and radiates a somewhat directional pattern toward the parabolic reflector. Focal feed - Using a focal point feed system the source of the radiation is placed at the focal point of the parabola and this is used to illuminate the reflector.

Question 63

If a slightly shorter parasitic element is placed 0.1 wavelength away from an HF dipole antenna, what effect will this have on the antenna's radiation pattern? A. A major lobe will develop in the horizontal plane, parallel to the two elements B. The radiation pattern will not be affected C. A major lobe will develop in the horizontal plane, toward the parasitic element D. A major lobe will develop in the vertical plane, away from the ground

Answer 63

C. A major lobe will develop in the horizontal plane, toward the parasitic element PARASITIC, SHORTER. A 'slightly shorter parasitic' element is the description of a Director'. A dipole and a 'director' in front of it make up a two-element Yagi.Radiation will be enhanced toward the director' at the expense of the back.

Question 64

One of the following consists of nonresonant antennas A. folded-dipole antenna B. end-fire antenna C. broadside antenna D. rhombic antenna

Answer 64

D. rhombic antenna

Question 65

If a magnetic-base whip antenna is placed on the roof of a car, in what direction does it send out radio energy? A. Most of it goes in one direction B. Most of it is aimed high into the sky C. It goes out equally well in all horizontal directions D. Most of it goes equally in two opposite directions

Answer 65

C. It goes out equally well in all horizontal directions An upright antenna element radiates equally well all around it in the horizontal plane.

Question 66

Indicate the antenna that is not wideband: A. folded dipole B. discone C. helical D. Marconi

Answer 66

D. Marconi

Question 67

How can the bandwidth of a parasitic beam antenna be increased? A. Use larger diameter elements B. Use tapered-diameter elements C. Use traps on the elements D. Use closer element spacing

Answer 67

A. Use larger diameter elements 'Antenna bandwidth' is the range of frequencies over which an antenna is usable. Larger-diameter elements means "ticker" elements. With "fatter" elements, resonance isn't as sharp. Antenna 'bandwidth' is increased.

Question 68

The most popular wideband driven array. A. yagi B. end fire C. log-periodic D. collinear

Answer 68

C. log-periodic

Question 69

Which is properly terminated antenna? A. hertz B. marconi C. dipole D. rhombic

Answer 69

D. rhombic Rhombic antenna is a non-resonant antenna that is capable of operating satisfactorily over a relatively wide bandwidth, making it ideally suited for HF transmission. The rhombic antenna is made of four non-resonant elements terminated in a resistor. Hertz antenna is also known as dipole antenna. A resonant antenna which is half-wavelength long. Marconi antenna is a quarter-wavelength long grounded antenna

Question 70

What is one effect of increasing the boom length and adding directors to a Yagi antenna? A. Wind load decreases B. Gain increases C. SWR increases D. Weight decreases

Answer 70

B. Gain increases More directors is the primary means of augmenting gain. [ Weight and 'wind load' certainly increase then. ]

Question 71

An example of a Marconi antenna is A. rhombic B. yagi C. quarter wave vertical tower D. collinear

Answer 71

C. quarter wave vertical tower Marconi antenna is a quarter-wavelength long grounded antenna Rhombic antenna is a non-resonant antenna that is capable of operating satisfactorily over a relatively wide bandwidth, making it ideally suited for HF transmission. The rhombic antenna is made of four non-resonant elements terminated in a resistor. Collinear array is an array of dipole antennas mounted in such a manner that every element of each antenna is in an extension, with respect to its long axis, of its counterparts in the other antennas in the array. Yagi-uda antenna is an array of consisting of driven elements and one or more parasitic elements.

Question 72

____ is the propagation method subject to the greatest distortion. A. Multimode Graded-index B. Multimode step-index C. Multiple single-index D. Single-mode

Answer 72

B. Multimode step-index

Question 73

In ____ propagation, the beam of propagated light is almost horizontal, and the low-density core has a small diameter compared to the cores of the other propagation modes. A. Multiple graded-index B. Multimode step-index C. Multimode single-index D. Single-mode

Answer 73

D. Single-mode

Question 74

Optical fibers, unlike wire media, are highly resistant to ____ A. Electromagnetic interference B. Refraction C. High-frequency transmission D. Low-frequency transmission

Answer 74

A. Electromagnetic interference

Question 75

In _____ propagation, the core is varying densities. A. Multimode single-index B. Multimode step-index C. Single-mode D. Multimode graded-index

Answer 75

D. Multimode graded-index

Question 76

The Philippine Electronics Code or the Code of Technical Standards of Practice for Professional Electronics Engineers, Electronics Engineers and Electronics Technicians defines distribution architectures in Cable TV system. Which type of Cable TV distribution arrangement fiber-fed termination units are shared by several dwellings? A. FTTH - Fiber to the home B. FTTP - Fiber to the premises C. FTTF - Fiber to the feeder D. FTTC - Fiber to the curb

Answer 76

D. FTTC - Fiber to the curb

Question 77

Level or Category of UTP cable which was developed for lEEE 802.5 token ring local area networks operating at a transmission rates of 4 Mbps A. Level 1 or Cat 1 B. Level 2 or Cat 2 C. Level 3 or Cat 3 D. Cat 4

Answer 77

B. Level 2 or Cat 2

Question 78

In laser transmission, which is a measure of the transmission time as a function of the orientation of the E-field of the light relative to the fiber? A. Optical modulation index B. Rise time C. Polarization mode dispersion D. Phase noise index

Answer 78

C. Polarization mode dispersion

Question 79

Which microwave oscillator has high gain, low-noise characteristics, and wide bandwidth? A. Traveling wave tube oscillator B. Gunn Oscillator C. Klystron oscillator D. Magnetron oscillator

Answer 79

A. Traveling wave tube oscillator

Question 80

The usual velocity factor of coaxial cable A. 0.8 to 0.9 B. 0.3 to 0.4 C. 0.4 to 0.5 D. 0.6 to 0.7

Answer 80

D. 0.6 to 0.7

Question 81

Which UTP category has the maximum data rate of 100 Mbps? A. Cat 1 B. Cat 3 C. Cat 6 D. Cat 5

Answer 81

D. Cat 5

Question 82

The maximum energy of electrons liberated photoelectrically is A. proportional to light intensity and independent of frequency of light B. proportional to both, light intensity and frequency of the light C. independent of light intensity and varies linearly with frequency of the light D. independent of light intensity and inversely proportional to frequency of the light

Answer 82

C. independent of light intensity and varies linearly with frequency of the light By conservation of energy, this reasoning led Einstein to the photoelectric equation Ek = hf - Φ, where Ek is the maximum kinetic energy of the ejected electron.

Question 83

When the temperature of a measuring device is lower than or equal to reference temperature then the temperature sensor treats the temperature value as ____ temperature. A. Low temperature B. Saturation temperature C. Room temperature D. High temperature

Answer 83

A. Low temperature When the temperature of a measuring device is lower than or equal to reference temperature then the temperature sensor treats the temperature value as low temperature.

Question 84

If at one end, the two wires made of different metals are joined together then a voltage will get produced between the two wires due to difference of temp between the two ends of wires. This effect is observed in A. RTD B. Ultrasonics C. Thermistors D. Thermocouples

Answer 84

D. Thermocouples In 1821, German physicist Thomas Seebeck discovered that when two wires made from dissimilar metals are joined at two ends to form a loop, and if the two junctions are maintained at different temperatures, a voltage develops in the circuit. Seebeck effect is therefore named after him. This effect is observed in thermocouples.

Question 85

To emit the light through surface, doping concentration of the substrate must be ____ A. Decreased B. Depends on the situation C. Randomly increase or decrease D. Increased

Answer 85

D. Increased To emit the light through surface, doping concentration of the substrate must be increased.

Question 86

The standard form of RTU is A. Reverse Terminal Unit B. None of these choices C. Remote Terminal Unit D. Reverse Unit

Answer 86

C. Remote Terminal Unit The standard form of RTU is Reverse Terminal Unit that is sometimes called as Remote Telemetry Unit or Remote Telecontol Unit.

Question 87

Which one is the oldest programming language? A. Structured text programming B. Ladder logic C. None of these choices D. Function block diagram

Answer 87

B. Ladder logic The ladder logic is one type of the oldest programming language.

Question 88

____ is connected to the PLC input. A. Indicating lamp B. None of these choices C. Alarm D. Field sensors

Answer 88

D. Field sensors Input devices can be Transducer, Sensors, Switches, Push Button which is connected with PLC.

Question 89

Consider the following statements regarding Programmable Logic Controller: 1. It was developed to replace the microprocessor. 2. Wiring between devices and relay contacts are done in its program. 3.Its 1/0 interface section connects it to external field devices. 4. It requires extensive wiring in the application. Which of the above statements are correct? A. 1 and 4 B. 1 and 3 C. 2 and 4 D. 2 and 3

Answer 89

D. 2 and 3 • A Programmable Logic Controller, or PLC for short, is simply a special computer device used for industrial control systems. • They are used in many industries such as oil refineries, manufacturing lines, conveyor systems and so on. Where ever there is a need to control devices the PLC provides a flexible way to "softwlre" the components together. • PLCs come in many shapes and sizes. They can be so small as to fit in your shirt pocket while more involved controls systems require large PLC racks. • 1/0 - The PLC's CPU stores and processes program data, but input and output modules connect the PLC to the rest of the machine; these I/0 modules are what provide information to the CPU and trigger specific results. • 1/0 can be either analog or digital;input devices might include sensors,switches, and meters, while outputs might include relay, light, valves and drives. Users can mix and match a PLC's I/0 in order to get the right configuration for their application. Option 1 and 4 are wrong because; • PLC does not replace microprocessor infact it is part of PLC. • It does not require extensive wiring by PLC.

Question 90

The purpose of using a three-wire power cord and plug on amateur radio equipment is to: A. prevent short circuits B. make it inconvenient to use C. prevent the plug from being reversed in the wall outlet D. prevent the chassis from becoming live in case of an internal short to the chassis

Answer 90

D. prevent the chassis from becoming live in case of an internal short to the chassis The 'green wire' in a three-wire AC line cord is a ground connection. Securing the 'green wire' to the chassis (and outside cabinet) keeps the chassis at ground potential if a fault ever caused the 'live' side (120 Volts) of the AC line to contact the chassis.

Question 91

Why should you ground all antenna and rotator cables when your amateur station is not in use? A. To make sure everything will stay in place B. To protect the station and building from lightning damage C. To lock the antenna system in one position D. To avoid radio frequency interference

Answer 91

B. To protect the station and building from lightning damage Grounding antenna and rotator cables help direct an eventual lightning strike as directly to ground as possible.

Question 92

In closed loop control system, with positive value of feedback gain the overall gain of the system will A. increase B. be unaffected C. decrease D. Any of these choices

Answer 92

C. decrease Closed loop control system, can be both positive and negative and with positive value of feedback gain where the overall gain of the system will increase and also the oscillations.

Question 93

Which of the following should be done to make an unstable system stable? A. The gain of the system should be increased B. The number of zeros to the loop transfer function should be increased C. The gain of the system should be decreased D. The number of poles to the loop transfer function should be increased

Answer 93

A. The gain of the system should be increased The gain of the system should be increased to make an unstable system stable and for positive feedback of the system the gain is more and for the negative feedback the gain is reduced for which the stable system can become unstable.

Question 94

Which statement about station grounding is true? A. RF hot spots can occur in a station located above the ground floor if the equipment is grounded by a long ground wire B. The chassis of each piece of station equipment should be tied together with high-impedance conductors C. A ground loop is an effective way to ground station equipment D. If the chassis of all station equipment is connected with a good conductor, there is no need to tie them to an earth ground

Answer 94

A. RF hot spots can occur in a station located above the ground floor if the equipment is grounded by a long ground wire RF 'hot spots' and RF 'burns' are symptoms of 'Stray RF'. To eliminate 'Stray RF', a low impedance path to ground must be provided. Only SHORT and WIDE ground conductors can provide low impedance.

Question 95

In an open loop control system A. None of these choices B. Output is dependent on control input C. Output is independent of control input D. Only system parameters have effect on the control output

Answer 95

C. Output is independent of control input An Open-loop system, also referred to as non-feedback system, is a type of continuous control system in which the output has no influence or effect on the control action of the input signal. In other words, in an open-loop control system the output is neither measured nor "fed back" for comparison with the input. Therefore, an open-loop system is expected to faithfully follow its input command or set point regardless of the final result.

Question 96

Which of the following is the common application of Air standard refrigeration system? A. Car air conditioning system B. Cold storage C. Domestic refrigerators D. Aircraft air conditioning

Answer 96

D. Aircraft air conditioning As a sufficient amount of air is obtained while aviation of air crafts, the only thing is to reduce its velocity, and then it can be used for air conditioning in air crafts.

Question 97

On mains operated power supplies, the ground wire should be connected to the metal chassis of the power supply. This ensures, in case there is a fault in the power supply, that the chassis: A. does not develop a high voltage with respect to the ground B. becomes conductive to prevent electric shock C. develops a high voltage compared to the ground D. does not become conductive to prevent electric shock

Answer 97

A. does not develop a high voltage with respect to the ground The 'green wire' in a three-wire AC line cord is a ground connection. Securing the 'green wire' to the chassis (and outside cabinet) keeps the chassis at ground potential if a fault ever caused the 'live' side (120 Volts) of the AC line to contact the chassis.

Question 98

For open control system which of the following statements is incorrect? A. Errors are caused by disturbances B. Construction is simple and maintenance easy C. Recalibration is not required for maintaining the required quality of the output D. Less expensive

Answer 98

C. Recalibration is not required for maintaining the required quality of the output Recalibration is not required for maintaining the required quality of the output for open control systems.

Question 99

Why should you make sure the antenna of a hand-held transceiver is not close to your head when transmitting? A. To keep static charges from building up B. To reduce your exposure to the radio- frequency energy C. To help the antenna radiate energy equally in all directions D. To use your body to reflect the signal in one direction

Answer 99

B. To reduce your exposure to the radio- frequency energy RF energy can heat body tissue. VHF and UHF frequencies present the greatest risk. 30 MHz to 300 MHz is the range of radio-frequencies over which Health-Canada's "Safety Code 6" recommends the lowest exposure level.