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Chapter 7
1 Electromagnetic waves are created by:
a.* The alternating RF currents in an antenna.
b. Magnetic solenoids.
c. Audio loudspeakers.
d. DC voltages.
2 In electromagnetic radiation, which of the following is true?
a.* E and H are at 180° to each other.
b. E, H and the direction of propagation are all at right angles
to each other.
c. The angle between E and H is 0 °.
d. The velocity of propagation is at 180° to the E field but in
line with the H field.
3 In order to radiate, an electromagnetic wave must have:
a. E Field only.
b. H Field only.
c.* A and H Field
d. Air to travel in.
4 Polarization of an electromagnetic wave is fixed by:
a. The direction of the H field.
b. The direction of propagation.
c. By an anti-phase signal.
d.* The orientation of the transmitting antenna.
5 A field strength meter, when used to check an antenna's
radiation pattern, would best approximate a:
a. Dip oscillator.
b. Power meter.
c. Reflectometer.
d.* Diode receiver.
6 The wavelength of a signal of 100MHz in free space is:
a. 30 mm
b. 0.3 m
c.* 3.0 m
d. 30.00 m
7 hat is the transmission path of a wave that travels directly
from the transmitting antenna to the receiving antenna called?
a. * The ground wave.
b. The sky wave.
c. The linear wave.
d. The plane wave.
8 What effect does tropospheric bending have on 2 meter radio
waves?
a.* It increases the distance over which they can be transmitted.
b. It decreases the distance over which they can be transmitted.
c. It tends to garble 2-meter phone transmissions.
d. It reverses the sideband of 2-meter phone transmissions.
9 Two stations 5 Km apart are most likely to be communicating via:
a. Tropospheric waves.
b. Ionospheric waves.
c.* Ground waves.
d. Telephone.
10 The D layer occurs in the Ionosphere at :
a.* 80 km.
b. 150 km.
c. 200 km.
d. 300 km.
11 The F2 layer occurs at:
a. 80 km above the earth.
b. 150 km above the earth.
c. 100 to 200 km above the earth.
d.* 200 to 300 km above the earth.
12 The ionospheric layer that mostly affects long distance radio
communications is:
a. D layer.
b. E layer.
c. F1 layer.
d.* F2 layer.
13 Signals above the maximum usable frequency passing through the
F2 layer:
a. Are reflected to earth.
b.* Pass through and are lost in space.
c. Are amplified.
d. Are attenuated and refracted.
14 When the resonant length of an antenna matches the transmitted
frequency:
a. Maximum power will be reflected.
b.* A good SWR will be obtained.
c. The SWR will be poor.
d. An SWR reading will be meaningless.
15 What do the terms vertical and horizontal, as applied to wave
polarization, refer to?
a.* Orientation of the electric lines of force.
b. Orientation of the magnetic lines of force.
c. Orientation of the charge particles in the propagation medium.
d. Launching angle of the wave with respect to the earth's
surface.
16 What radiation pattern does an ideal half-wave dipole have if
it is installed parallel to the earth?
a.* It radiates well in both directions parallel to the earth and
perpendicular to the dipole;
b. It radiates poorly in directions parallel to the earth and
parallel to the dipole.
c. It radiates equally well in all directions parallel to the
earth.
d. It radiates poorly in all directions parallel to the earth, but
it radiates well in directions perpendicular to the earth.
17 How does proximity to the ground affect the radiation pattern
of a horizontal dipole antenna?
a. If the antenna is too far from the ground, the pattern becomes
unpredictable.
b.* If the antenna is less than one-half wavelength from the
ground, reflected radio waves from the ground distort the
radiation pattern of the antenna.
c. A dipole antenna's radiation pattern is unaffected by its
distance to the ground.
d. If the antenna is less than one-half wavelength from the
ground, radiation off the ends of the wire is reduced.
18 To achieve the furthest possible skip distance:
a. The angle of radiation of the antenna must be high.
b. Maximum power should be used.
c.* A low angle of radiation is recommended.
d. An antenna should be close to the earth.
19 Which kind of antenna would be least affected by signal
emanating from a particular direction, while enhancing the signals
from a desired direction?
a. A monopole antenna.
b. An isotropic antenna.
c. A vertical antenna.
d.* A beam antenna.
20 What is a directional antenna?
a. An antenna whose parasitic elements are all constructed to be
directors.
b. An antenna that radiates in direct line-of-sight propagation,
but not sky wave or skip propagation.
c. An antenna permanently mounted so as to radiate in only one
direction.
d.* An antenna that radiates more strongly in some directions than
others.
21 What is a balanced transmission line?
a.* A transmission line constructed of two equal-size parallel
conductors.
b. A transmission line constructed of two coaxial conductors.
c. A transmission line with voltage and current in phase at all
points.
d. A transmission line constructed of two parallel and concentric
conductors.
22 What is a balun?
a.* A device for matching an unbalanced line to supply power to a
balanced load, or vice-versa.
b. A device to match impedances between two coaxial lines.
c. A device used to connect a microphone to a balanced modulator.
d. A counterbalance used with an azimuth/elevation rotator system.
23 What is the purpose of an antenna matching circuit?
a. To measure the impedance of the antenna.
b. To compare the radiation patterns of two antennas.
c. To measure the SWR of an antenna.
d.* To match impedances within the antenna systems.
24 When will a power source deliver maximum output?
a.* When the impedance of the load is equal to the impedance of
the source.
b. When the SWR has reached a maximum value.
c. When the power supply fuse rating equals the primary winding
current.
d. When air wound transformers are used instead of iron core
transformers.
25 hat is a Yagi antenna?
a. Half-wavelength elements stacked vertically and exited in
phase.
b. Quarter-wavelength elements arranged horizontally and excited
out of phase.
c.* Half-wavelength linear driven element(s) with parasitically
excited parallel linear elements.
d. Quarter-wavelength, triangular loop elements.
26 Why is a Yagi antenna often used for amateur radio
communications on the 20 meter band?
a. It provides excellent omniderectional coverage in the
horizontal plane.
b. It is smaller, less expensive and easier to erect than a
dipole or vertical antenna.
c.* It discriminates against interference from other stations off
to the side or behind.
d. It provides the highest possible angle of radiation for the HF
bands.
27 Choose a physical description of the radiating elements of a
horizontally-polarized Yagi antenna.
a.* Two or more straight, parallel elements arranged in the same
horizontal plane.
b. Vertically stacked square or circular loops arranged in
parallel horizontal planes.
c. Two or more wire loops arranged in parallel vertical planes.
d. A vertical radiator arranged in the centre of an effective RF
ground plane.
28 What is the name of the parasitic beam antenna using two or
more straight metal-tubing elements arranged physically parallel
to each other?
a. A quad antenna.
b. A delta loop antenna.
c. A zepp antenna.
d.* A Yagi antenna.
29 How many driven elements does a Yagi antenna have?
a. None; they are all parasitic.
b.* One.
c. Two.
d. All elements are driven.
30 What kind of antenna array is composed of a square or
diamond-shaped full-wave closed loop driven element with parallel
parasitic element(s)?
a. Dual rhombic.
b.* Cubical quad.
c. Stacked yagi.
d. Delta loop.
31 What is the polarization of the signal from a half-wavelength
antenna which has elements perpendicular to the earth's surface?
a. Circularly polarized waves.
b. Horizontally polarized waves.
c. Parabolically polarized waves.
d.* Vertically polarized waves.
32 A two trap dipole will allow operation on:
a. One band.
b. All bands.
c.* Three bands.
d. Two bands.
33 A folded dipole has an approximate impedance of:
a. 50 Ohm.
b. 72 Ohm.
c. 150 Ohm.
d.* 300 Ohm.
34 A vertical antenna relies upon :
a.* A good earth and ground connection.
b. No earthing.
c. A sensitive receiver.
d. The D layer.
35 The term Zepp, Yagi, Quad and Log Periodic refer to:
a. Oscillators.
b. Transistors.
c.* Antennas.
d. Diodes.
36 A dipole antenna length is:
a.* Half a wavelength.
b. 5/8th of a wavelength.
c. A full wavelength.
d. A Quarter of a wavelength. |
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