- Antenna -

-

Which antenna does not use the ground?

a. Marconi

b. Yagi

c. Hertz

d. Rhombic

ans: b

-

What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?

a. It is increased

b. It is decreased

c. No change occurs

d. It becomes fast

ans: a

-

What is the polarization of a discone antenna?

a. Vertical

b. Horizontal

c. Circular

d. Spiral

ans: a

-

If the antenna increases 3.3 times, how much does the radiated power increase?

a. 3.3 times

b. 10.89 times

c. 9.9 times

d. 6.6 times

ans: b

-

When speaking of antennas, ___________ is a section which would be a complete antenna by itself.

a. image

b. top loading

c. bay

d. quarterwave

ans: c

-

In what range of frequencies are most omnidirectional horizontally polarized antennas used?

a. VHF, UHF

b. VLF, LF

c. SH, EHF

d. MF, HF

ans: a

-

If the current ratios of the two or more elements must be held 5% and the phase angle to 3 degrees,

the antenna is called a

a. end fire array

b. critical phased array

c. broadband array

d. wideband array

ans: b

-

A device that converts high frequency current into electromagnetic wave.

a. Antenna

b. Loudspeaker

c. Microphone

d. Transducer

ans: a

-

Which is a non-resonant antenna?

a. Rhombic antenna

b. Folded dipole

c. End-fire array

d. Yagi-Uda antenna

ans: a

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Gain of a half-wave dipole antenna over isotropic.

a. 2.15 dB

b. 1.76 dB

c. 1 dB

d. 0 dB

ans: a

-

Very low signal strength in antenna.

a. Minor lobes

b. Null

c. Antenna patterns

d. Major lobes

ans: b

-

What is the gain of the Hertzian dipole over isotropic antenna?

a. 1.64 dB

b. 2.15 dB

c. 1.76 dB

d. 1.55 dB

ans: c

-

____________ is the measurement of a unilateral antenna properties of directivity.

a. Phase angle

b. Antenna gain

c. Beamwidth

d. Bandwidth

ans: c

-

In testing transmitter to prevent interfering with other stations, which type of antenna must be used?

a. Void antenna

b. Dummy antenna

c. Hertzian antenna

d. Isotropic antenna

ans: b

-

The best solution of fading is ____________.

a. space diversity

b. frequency diversity

c. polarization diversity

d. wavelength diversity

ans: a

-

_____________ is the amount of uncertainty in a system of symbols.

a. Bandwidth

b. Enthalpy

c. Entropy

d. Quantum

ans: c

-

If an antenna has a gain of 30 dB, it increases the output of the transmitter by

a. 10,000 times

b. 1000 times

c. 100 times

d. 1 million times

ans: b

-

Top loading is used in an antenna in order to increase its _______________.

a. practical height

b. beamwidth

c. effective height

d. input capacitance

ans: c

-

A horizontal antenna is ______________.

a. vertically polarized

b. horizontally polarized

c. centrally polarized

d. circularly polarized

ans: b

-

All elements in a beam ____________ antennas are in line.

a. collinear

b. yagi

c. broadside array

d. log-periodic

ans: a

-

Which does not use vertical polarization antenna?

a. AM Broadcasting

b. FM Broadcasting

c. Mobile Communications

d. Satellite Communications

ans: b

-

Lightning rods must be mounted a top structure not less than ____________ above the highest point.

a. 10 cm

b. 20 cm

c. 30 cm

d. 40 cm

ans: c

-

_________________ is the antenna with a number of half-wave antenna on it.

a. Antenna array

b. Tower

c. Omni-directional

d. Rhombic

ans: a

-

Which antenna radiates an omnidirectional pattern in the horizontal plane with vertical polarization?

a. Marconi antenna

b. Discone antenna

c. Horn antenna

d. Helical antenna

ans: a

-

An antenna with very high gain and very narrow beamwidth.

a. Helical antenna

b. Discone antenna

c. Horn antenna

d. Parabolic dish antenna

ans: d

-

What determines antenna polarization?

a. The frequency of the radiated wave

b. The direction of the radiated wave

c. The direction of the magnetic field vector

d. The direction of the electric field vector

ans: d

-

______________ is the horizontal pointing angle of an antenna.

a. Azimuth

b. Angle of elevation

c. Right angle

d. Beamwidth

ans: a

-

A dipole antenna requires to be fed with 20 kW of power to produce a given signal strength to a

particular distant pt. If the addition of a reflector makes the same field strength available with an input

power of 11 kW. What is the gain in dB, obtained by the use of the reflector. (Gain referred to this

particular dipole).

a. 4.75

b. 2.6

c. 1.81

d. 4.24

ans: b

-

What is the estimated medium wind loading in the Philippines for antenna tower design?

a. 300 kph

b. 100 kph

c. 200 kph

d. 250 kph

ans: c

-

Discone radiation pattern is _____________.

a. omnidirectional

b. unidirectional

c. bidirectional

d. figure of eight

ans: a

-

______________ is an open-ended slot antenna.

a. Helical antenna

b. Rhombic antenna

c. Notch antenna

d. Cassegrain antenna

ans: c

-

Which antenna is a properly terminated?

a. Marconi

b. Rhombic

c. Dipole

d. Yagi-Uda

ans: b

-

What is the radiation characteristic of a dipole antenna?

a. Omnidirectional

b. Bidirectional

c. Unidirectional

d. Hemispherical

ans: b

-

What is the theoretical gain of a Hertzian dipole?

a. 1.76 dB

b. 2.15 dB

c. 3 dB

d. 0 dB

ans: a

-

An antenna with unity gain.

a. Rhombic

b. Half-wave dipole

c. Isotropic

d. Whip

ans: c

-

How will you increase the gain of an antenna?

a. By adding several antennas in parallel

b. By focusing the radiated energy in one desired direction

c. By making antenna rods thicker

d. By making the antenna size larger

ans: b

-

An antenna which is one-tenth wavelength long.

a. Hertzian dipole

b. Loop antenna

c. Marconi antenna

d. Elementary doublet

ans: d

-

What is the minimum number of turns a helix antenna must have?

a. 3

b. 5

c. 4

d. 6

ans: a

-

What is the gain of isotropic antenna?

a. 10

b. 1

c. 10

d. 100

ans: b

-

Which of the following improves antenna directivity?

a. Driven element

b. Reflector element

c. Director element

d. Parasitic element

ans: d

-

The antenna radiates __________ polarized waves when the transmitter antenna is horizontally

installed.

a. Vertically

b. negatively

c. horizontally

d. circularly

ans: c

-

The length of a Marconi antenna to operate with 985 kHz is ___________.

a. 200 ft

b. 500 ft

c. 250 ft

d. 999 ft

ans: c

-

What is the front-to-back ratio of an antenna which radiates 500 watts in a northernly direction and 50

watts in a southernly direction?

a. 25000 dB

b. 10 dB

c. 100 dB

d. 20 dB

ans: b

-

If 4 kW in antenna produces 50 uV/m in a receiving antenna, a 16 kW will produce __________.

a. 200 uV/m

b. 10 uV/m

c. 100 uV/m

d. 20 uV/m

ans: c

-

If the radiated power increase 10.89 times, the antenna current increases by ____________.

a. 3.3 times

b. 6.6 times

c. 1.82 times

d. 10.89 times

ans: a

-

The frequency of operation of a dipole antenna cut to a length of 3.4 m.

a. 88 MHz

b. 44 MHz

c. 22 MHz

d. 11 MHz

ans: b

-

Comparing the signal strength arriving at the driven element from the desired direction to the signal

strength reaching the driver from the opposite direction.

a. Directivity

b. Sensitivity

c. Beamwidth

d. Front-to-back ratio

ans: d

-

What is the capture area of a dipole operated at 75 MHz?

a. 44 mm^2

b. 2 m^2

c. 2.088 m^2

d. 4.088 m^2

ans: c

-

________________ of an antenna is a measure of how the antenna concentrates its radiated power in

a given direction.

a. Efficiency

b. Power

c. Gain

d. Polarization

ans: c

-

Shortening effect of an antenna that makes it appear as if it were 5% longer.

a. End effect

b. Flywheel effect

c. Skin effect

d. Capture effect

ans: a

-

Harmonic suppressor connected to an antenna.

a. Low-pass filter

b. High-pass filter

c. M-derived filter

d. Constant-K

ans: a

-

A simple half-wavelength antenna radiates the strongest signal

a. at 45 degrees to its axis

b. parallel to its axis

c. at right angles to its axis

d. at 60 degrees to its axis

ans: c

-

The current maximum in a Marconi antenna is found at

a. the base of the antenna

b. the center of the antenna

c. some point between the base and the center of the antenna

d. the top of the antenna

ans: a

-

If an antenna is too short for the wavelength being used, the effective length can be increased by

adding:

a. capacitance in series

b. inductance in series

c. resistance in parallel

d. resistance in series

ans: b

-

Which of the following antennas is used for testing and adjusting a transmitter for proper modulation,

amplifier operation and frequency accuracy?

a. Elementary

b. Real

c. Isotropic

d. Dummy

ans: d

-

The power fed to a two-bay turnstile antenna is 100 watts. If the antenna has a 2dB power gain, what is

the effective radiated power?

a. 317 watts

b. 158 watts

c. 200 watts

d. 400 watts

ans: b

-

What is the gain, in dB of a helical antenna with diameter of lambda/3, 10 turns at pitch of lambda/4,

used at 100 MHz?

a. 16

b. 41.1

c. 31.4

d. 1.25

ans: a

-

How is it possible to lower the resonant frequency of Hertz dipole antenna?

a. By reducing the frequency at the transmitter

b. By connecting a capacitor in series with the antenna

c. By connecting a resistor in series with the antenna

d. By connecting an inductor in series with the antenna

ans: d

-

Which of the following antennas receive signals in the horizontal plane equally well from all directions?

a. Horizontal Hertz antenna

b. Vertical loop antenna

c. Vertical Yagi antenna

d. A vertical antenna which is a quarter-wavelength long

ans: d

-

If the length of a Hertz dipole is decreased

a. its resonant frequency will be lowered its distributed inductance will be increased.

b. its distributed inductance will be decreased

c. its resonant frequency will be increased

d. its distributed capacitance between the antenna and ground will be increased

ans: c

-

A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is

1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a

feed impedance of 70 ohms, what is the antenna current at the feed-point?

a. 4.0 A

b. 2.2 A

c. 1.25 A

d. 2.0 A

ans: d

-

A one-quarter wavelength shunt-fed vertical Marconi antenna

a. has maximum radiation in a vertical direction

b. must have a horizontal receiving antenna for the best reception

c. must use a receiving antenna for the best reception

d. must have a vertical receiving antenna for the best reception

ans: d

-

A shunt-fed quarter-wavelength Marconi antenna

a. has maximum RF impedance to ground at its feedpoint

b. has a current null at its feedpoint

c. has zero DC resistance to ground

d. has zero RF resistance to ground

ans: c

-

The parasitic element of an antenna system will

a. decrease its directivity

b. increase its directivity

c. give the antenna unidirectional properties

d. both B and C

ans: d

-

If the length of an antenna is changed from 2.5 meters to 2.8 meters, its resonant frequency will

a. increase

b. depend on the velocity factor so the resonant frequency can either be increased or decreased

c. will be unchanged

d. decrease

ans: d

-

What is the effect of adding a capacitor in series with an antenna?

a. The antenna's resonant frequency will increase

b. The antenna's resonant frequency will decrease

c. The antenna will be physically 5% longer than its electrical length

d. A capacitor is never added in series with an antenna

ans: a

-

How does the electric field strength of a standard broadcast station vary with the distance from the

antenna?

a. The field strength of a standard broadcast station vary with the distance from the antenna

b. The field strength is directly proportional to the distance from the antenna

c. The field strength remains constant regardless of the distance from the antenna

d. The field strength varies inversely as the distance from the antenna

ans: d

-

Stacking elements in a transmitting antenna system

a. increases the field strength at the receiving antenna

b. increases the directivity of the transmitter antenna

c. decrease the size of the lobe in the radiation pattern

d. both A and B

ans: d

-

A vertical loop antenna has a

a. unidirectional radiation pattern in the horizontal plane

b. unidirectional radiation pattern in the vertical plane

c. omnidirectional radiation pattern in the horizontal plane

d. a bidirectional radiation pattern in the horizontal plane

ans: d

-

In order to get maximum radiation to all surrounding points in the horizontal plane, the antenna used is

a

a. vertical loop

b. vertical quarter-wavelength rod

c. array which includes parasitic elements

d. a horizontal Hertz dipole

ans: b

-

What is the electrical wavelength of a 500 MHz signal?

a. 60 centimeters

b. 6 meters

c. 0.06 meter

d. 60 meters

ans: a

-

If the antenna current is doubled, the field strength at a particular position is

a. doubled

b. halved

c. multiplied by a factor of four

d. divided by a factor of four

ans: a

-

The rhombic antenna is primarily used for

a. ground wave propagation

b. space wave propagation

c. ionospheric scatter propagation

d. sky wave propagation

ans: d

-

What antenna radiates equally in all directions?

a. Vertical antenna

b. Isotropic antenna

c. Horizontal antenna

d. Dipole antenna

ans: b

-

Actual height of antenna should be at least

a. one wavelength

b. half wavelength

c. quarter wavelength

d. three-fourth wavelength

ans: c

-

Which antenna is not properly terminated?

a. Resonant

b. Non-resonant

c. Isotropic

d. Whip

ans: a

-

_______________ is an antenna array which is highly directional at right angles to the plane of the

array?

a. Broadside array

b. End-fire array

c. Turnstile array

d. Log-periodic array

ans: a

-

The directivity pattern of an isotropic radiator is

a. a figure-8

b. a sphere

c. a unidirectional cardioid

d. a parabola

ans: b

-

An isotropic radiator is

a. in the northern hemisphere

b. an antenna high enough in the air

c. an antenna whose directive pattern is substantially incredible

d. a hypothetical, omnidirectional antenna

ans: d

-

The purpose of stacking elements on an antenna.

a. Sharper directional pattern

b. Increased gain

c. Improved bandpass

d. All of these

ans: d

-

The advantage of using top loading in a shortened HF vertical antenna is

a. lower quality factor

b. greater structural strength

c. higher losses

d. improved radiation efficiency

ans: d

-

Where are the voltage nodes in a half-wave antenna?

a. At the ends

b. Three-quarters of the way from the feed point toward the end

c. One-half of the way from the feed point toward the end

d. At the feed point

ans: d

-

A theoretical reference antenna that provides a comparison for antenna measurements.

a. Marconi antenna

b. Isotropic radiator

c. Yagi-Uda array

d. Whip antenna

ans: b

-

A Hertz antenna is operating on a frequency of 2182 kHz and consists of a horizontal wire that is

hanged between two towers. What is the frequency of its third harmonic?

a. 727 kHz

b. 6546 kHz

c. 436 kHz

d. 6.546 kHz

ans: b

-

In horizontal-dipole antenna, the polarization is

a. in the vertical direction

b. in the horizontal direction

c. circular

d. measured at the center of the antenna

ans: b

-

Increasing the electrical length of an antenna means

a. add an inductor in parallel

b. add a capacitor in series

c. add an inductor in series

d. add a resistor in series

ans: c

-

Stacking antennas at various angles results in

a. a more omnidirectional reception

b. a more unidirectional reception

c. a less omnidirectional reception

d. an overall reception signal increase

ans: a

-

What is driven element?

a. Almost the rearmost element

b. Always the forward most element

c. The element fed by the transmission line

d. The element connected to the rotator

ans: c

-

What is antenna bandwidth?

a. Antenna length divided by the number of elements

b. The angle between the half-power radiation points

c. The angle formed between two imaginary lines drawn through

d. The frequency range over which an antenna can be expected to operate satisfactorily

ans: d

-

To lengthen an antenna electrically, add a

a. resistor

b. battery

c. conduit

d. coil

ans: d

-

What is the gain of an antenna over a half-wavelength dipole when it has 6 dB gain over an isotropic

radiator?

a. 6.0 dB

b. 8.1 dB

c. 3.9 dB

d. 10.0 dB

ans: c

-

What is the usual electrical length of a driven element in an HF beam antenna?

a. 1/4 wavelength

b. 3/4 wavelength

c. 1/2 wavelength

d. 1 wavelength

ans: c

-

To electrically decrease the length of an antenna,

a. add an inductor in the series

b. add an inductor in the parallel

c. add a resistor in the series

d. add a capacitor in the series

ans: d

-

Strong interference from one particular station can be eliminated by the use of

a. noise limiters

b. squelch circuits

c. negative feedback

d. wave traps in the antenna circuitry

ans: d

-

It is useful to refer to an isotropic radiator

a. when comparing the gains of directional antennas

b. when testing a transmission line for standing wave ratio

c. when (in the northern hemisphere) directing the transmission

d. when using a dummy load to tune a transmitter

ans: a

-

A disadvantage of using a trap antenna.

a. It will radiate harmonics

b. It can only be used for single-band operation

c. It is too sharply directional at lower frequencies

d. It must be neutralized

ans: a

-

The input terminal impedance at the center of a folded dipole antenna is

a. 72 ohms(s)

b. 300 ohms(s)

c. 50 ohms(s)

d. 73 ohms(s)

ans: b

-

When a capacitor is connected in series with a Marconi antenna?

a. Antenna open circuit stops transmission

b. An inductor of equal value must be added

c. No change occurs to antenna

d. Antenna resonant frequency increases

ans: d

-

Where are the current nodes in a half-wave antenna?

a. At the ends

b. At the center

c. Three-quarters of the way from the feed point toward the end

d. One-half of the way from the feed point toward the end

ans: a

-

For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce

the most effective performance?

a. As low as possible on the vertical radiator

b. Near the center of the vertical radiator

c. As close to the transmitter as possible

d. At a voltage node

ans: b

-

The effect of adding parasitic elements of a Hertz dipole is to

a. make the antenna more omnidirectional

b. reduce its resonant frequency

c. increase the antenna's power gain

d. all of these

ans: c

-

Stacking antenna elements

a. increases sensitivity to weak signals

b. will suppress odd harmonics

c. decrease signal to noise ratio

d. increase selectivity

ans: a

-

In the case of Marconi antenna, the actual length of the radiating element is

a. one-half wavelength

b. one-quarter wavelength

c. one wavelength

d. one-eight wavelength

ans: b

-

The antenna efficiency of an HF grounded vertical antenna can be made comparable to that of a half -

wave antenna.

a. By installing a good ground radial system

b. By isolating the coax shield from ground

c. By shortening the vertical

d. By lengthening the vertical

ans: a

-

An antenna "efficiency" is computed by using one of the following equations.

a. Efficiency = (radiation resistance / transmission resistance)

b. Efficiency = (total resistance / radiation resistance) x 100%

c. Efficiency = (effective radiated power / transmitter output) x 100%

d. Efficiency = (radiation resistance / total resistance) x 100%

ans: d

-

Increasing the resonant frequency of an end-fed Marconi antenna can be done by

a. adding a capacitor in series and reducing the physical length

b. adding an inductor in series

c. adding an inductor in parallel

d. all of these

ans: a

-

Factors that determine the radiation resistance of an antenna.

a. Transmission line length and height of antenna.

b. The location of the antenna with respect to nearby objects

c. It is a constant for all antennas since it is physical

d. Sunspot activity and the time of day

ans: b

-

______________ is the angle between the half-power radiation points.

a. Critical angle

b. Beamwidth

c. Angle of elevation

d. Azimuth

ans: b

-

What is the ratio of the maximum radiation intensity to the average radiation intensity?

a. Aperture gain

b. Directivity gain

c. Transmission gain

d. Power gain

ans: b

-

Good grounding is important for

a. horizontal antennas

b. broadside array antennas

c. vertical antennas

d. Yagi-Uda antennas

ans: c

-

An ungrounded antenna near the ground

a. acts as a single antenna of twice the height

b. is unlikely to need an earth mat

c. acts as antenna array

d. must be horizontally polarized

ans: c

-

One of the following is very useful as a multiband HF receiving antenna.

a. Parabolic antenna

b. Elementary doublet

c. Log-periodic

d. Square loop

ans: c

-

Which of the following antennas is best excited from a waveguide?

a. Biconical

b. Horn

c. Helical

d. Discone

ans: b

-

Indicate which of the following reasons for using metal counterpoise with antennas is false.

a. Impossibility of a good ground connection

b. Protection of personnel working underneath

c. Provision of an earth for the antenna

d. Rockiness of the ground itself

ans: b

-

Not a reason for the use of an antenna coupler.

a. To make the antenna look resistive

b. To provide the output amplifier with the correct load impedance

c. To discriminate against harmonics

d. To prevent reradiation of the local oscillator

ans: d

-

Which antenna is not a wideband?

a. Discone

b. Folded dipole

c. Helical

d. Marconi

ans: d

-

One of the following is not a reason for the use of an earth mat.

a. impossibility of a good ground connection

b. provision of an earth for the antenna

c. protection of personnel working underneath

d. improvement of the radiation pattern of the antenna

ans: c

-

One of the following makes an antenna physically long but electrically short.

a. Adding L in series

b. Adding C in series

c. Top loading

d. Both A and C

ans: b

-

When antennas are closed to the ground, ______________ polarization is ideal.

a. horizontally polarized

b. vertically polarized

c. circularly polarized

d. both A and B

ans: b

-

_____________ is an antenna made up of a number of full wavelengths.

a. Elementary doublet

b. Log-periodic

c. Long wire

d. Whip

ans: c

-

An energy which radiates in the form of radio waves, infrared waves, light waves, x -rays, etc.

a. Radiant energy

b. Electromagnetic

c. Heat

d. Ultraviolet

ans: b

-

Which one is an antenna coupling unit?

a. Coupler

b. Diplexer

c. Lecher wire

d. Duplexer

ans: b

-

_______________ polarization is employed in AM broadcasting.

a. Horizontal

b. Vertical

c. Circular

d. Omnidirectional

ans: b

-

_______________ polarization is employed in FM broadcasting.

a. Horizontal

b. Vertical

c. Circular

d. Bidirectional

ans: a

-

Which antenna is not grounded at one end?

a. Hertz

b. Marconi

c. Dipole

d. Whip

ans: c