Excel Review Center ECE Refresher/Coaching Course EST TH 1

A low pass filter in an HF station is most antenna In a single sideband and CW receiver, the
effective when connected: _______ is connected to the radio frequency
as close as possible to the transceiver output In a frequency modulation receiver, the amplifier and the high frequency oscillator.
* _______ is in between the antenna and the mixer
A low pass filter in an HF station is most mixer.
effective when connected: radio frequency amplifier * In a single sideband and CW receiver, the
as close as possible to the linear amplifier output of the _______ is connected to the
output * In a frequency modulation receiver, the output mixer.
of the high frequency oscillator is fed to the: high frequency oscillator *
In designing an HF station, which component mixer
would you use to reduce the effects of In a single sideband and CW receiver, the
harmonic radiation? In a frequency modulation receiver, the output _______ is in between the mixer and
Low pass filter of the _______ is connected to the mixer. intermediate frequency amplifier.
high frequency oscillator * filter
Which component in an HF station is the most
useful for determining the effectiveness of the In a frequency modulation receiver, the In a single sideband and CW receiver, the
antenna system? _______ is in between the mixer and the _______ is in between the filter and product
SWR bridge intermediate frequency amplifier. detector.
filter intermediate frequency amplifier *
Of the components in an HF station, which
component would normally be connected In a frequency modulation receiver, the In a single sideband and CW receiver, the
closest to the antenna, antenna tuner and _______ is located between the filter and the _______ output is connected to the audio
dummy load? limiter. frequency amplifier.
Antenna switch * intermediate frequency amplifier * product detector *

Of the components in an HF station, which In a frequency modulation receiver, the In a single sideband and CW receiver, the
component would be used to match _______ is in between the intermediate output of the _______ is connected to the
impedances between the transceiver and frequency amplifier and the frequency product detector.
antenna? discriminator. beat frequency oscillator *
Antenna tuner * limiter
In a single sideband and CW receiver, the
In an HF station, which component is In a frequency modulation receiver, the _______ is connected to the output of the
temporarily connected in the tuning process? _______ is located between the limiter and the product detector.
Dummy load * audio frequency amplifier. audio frequency amplifier *
frequency discriminator *
In an HF station, the antenna tuner is usually In a single sideband and CW receiver, the
used for matching the transceiver with: In a frequency modulation receiver, the _______ is connected to the output of the
most antennas when operating below 14 MHz _______ is located between the speaker and/or audio frequency amplifier.
* headphones and the frequency discriminator. speaker and/or headphones *
In an HF Station, the antenna tuner is audio frequency amplifier *
commonly used: In a single sideband transmitter, the output of
with most antennas when operating below 14 In a frequency modulation receiver, the the _______ is connected to the balanced
MHz * _______ connects to the audio frequency modulator.
amplifier output. radio frequency oscillator *
In a frequency modulation transmitter, the speaker and/or headphones *
input to the speech amplifier is connected to In a single sideband transmitter, the output of
the: In a CW transmitter, the output from the the _______ is connected to the filter.
Microphone _______ is connected to the driver/buffer. balanced modulator *
master oscillator *
In a frequency modulation transmitter, the In a single sideband transmitter, the _______
microphone is connected to the: In a typical CW transmitter, the _______ is the is in between the balanced modulator and the
speech amplifier * primary source of direct current. mixer.
power supply * filter
In a frequency modulation transmitter, the
_______ is in between the speech amplifier In a CW transmitter, the _______ is between In a single sideband transmitter, the _______
and the oscillator. the master oscillator and the power amplifier. is connected to the speech amplifier.
Modulator driver/buffer * microphone

In a frequency modulation transmitter, the In a CW transmitter, the _______ controls In a single sideband transmitter, the output of
_______ is located between the modulator and when RF energy is applied to the antenna. the _______ is connected to the balanced
the frequency multiplier. telegraph key * modulator.
oscillator speech amplifier *
In a CW transmitter, the _______ is in
In a frequency modulation transmitter, the between the driver/buffer stage and the In a single sideband transmitter, the output of
_______ is located between the oscillator and antenna. the variable frequency oscillator is connected
the power amplifier. power amplifier * to the _______.
frequency multiplier * mixer
In a CW transmitter, the output of the _______
In a frequency modulation transmitter, the is transferred to the antenna. In a single sideband transmitter, the output of
_______ is located between the frequency power amplifier * the _______ is connected to the mixer.
multiplier and the antenna. variable frequency oscillator *
power amplifier * In a single sideband and CW receiver, the
antenna is connected to the _______. In an single sideband transmitter, the _______
In a frequency modulation transmitter, the radio frequency amplifier * is in between the mixer and the antenna.
power amplifier output is connected to the: linear amplifier *
antenna * In a single sideband and CW receiver, the
output of the _______ is connected to the In a single sideband transmitter, the output of
In a frequency modulation receiver, the mixer. the linear amplifier is connected to the
_______ is connected to the input of the radio radio frequency amplifier * _______.
frequency amplifier. antenna

1
Excel Review Center ECE Refresher/Coaching Course EST TH 1
In a digital system, the _______ is controlled the suppressed carrier must be replaced for drift in frequency *
by the computer. detection *
input/output The input power to the final stage of your
A receiver receives an incoming signal of 3.54 transmitter is 200 watts and the output is 125
In a digital system, the modem is connected to MHz, and the local oscillator produces a signal watts. What has happened to the remaining
the _______. of 3.995 MHz. To which frequency should the power?
computer IF be tuned? It has been dissipated as heat loss
455 kHz
In a digital system, the transceiver is The difference between DC input power and
connected to the _______. What kind of filter would you use to attenuate RF output power of a transmitter RF amplifier:
Modem an interfering carrier signal while receiving an appears as heat dissipation *
SSB transmission?
In a digital system, the modem is connected to A notch filter What may happen if an SSB transmitter is
the _______. operated with the microphone gain set too
transceiver The three main parameters against which the high?
quality of a receiver is measured are: It may cause splatter interference to other
In a regulated power supply, the transformer sensitivity, selectivity and stability * stations operating near its frequency
connects to an external source which is
referred to as _______. A communications receiver has four filters What may happen if an SSB transmitter is
input installed in it, one at 250 Hz, one at 500 Hz, operated with too much speech processing?
one at 2.4 kHz, and one at 6 kHz. If you were It may cause splatter interference to other
In a regulated power supply, the _______ is listening to single sideband, which filter would stations operating near its frequency
between the input and the rectifier. you utilize?
transformer * 2.4 kHz What is the term for the average power
supplied to an antenna transmission line during
In a regulated power supply, the _______ is A communications receiver has four filters one RF cycle, at the crest of the modulation
between the transformer and the filter. installed in it, one at 250 Hz, one at 500 Hz, envelope?
rectifier one at 2.4 kHz and one at 6 kHz. You are Peak envelope power
copying a CW transmission and there is a great
In a regulated power supply, the output of the deal of interference. Which one of the filters What is the usual bandwidth of a single
rectifier is connected to the _______. would you choose? sideband amateur signal?
filter * 250 Hz Between 2 and 3 kHz

In a regulated power supply, the output of the Selectivity can be placed in the audio stages of In a typical single-sideband phone transmitter,
filter connects to the _______. a receiver by the utilization of RC active or what circuit processes signals from the
regulator * passive audio filters. If you were to copy CW, balanced modulator and sends signals to the
which of the following bandpasses would you mixer?
In a regulated power supply, the _______ is choose? Filter
connected to the regulator. 750 - 850 Hz
output What is one advantage of carrier suppression
What does chirp mean? in a double-sideband phone transmission?
In a Yagi-Uda 3 element directional antenna, A small change in a transmitter's frequency More power can be put into the sidebands
the _______ is primarily for mechanical each time it is keyed*
purposes. What happens to the signal of an
boom What can be done to keep a CW transmitter overmodulated single-sideband or double-
from chirping? sideband phone transmitter?
In a Yagi-Uda 3 element directional antenna, Keep the power supply voltages very steady It becomes distorted and occupies more
the _______ is the longest radiating element. bandwidth
reflector What circuit has a variable-frequency
oscillator connected to a driver and a power How should the microphone gain control be
In a Yagi-Uda 3 element directional antenna, amplifier? adjusted on a single-sideband phone
the _______ is the shortest radiating element. A VFO-controlled transmitter transmitter?
director For slight movement of the ALC meter on
What type of modulation system changes the modulation peaks *
In a Yagi-Uda 3 element directional antenna, amplitude of an RF wave for the purpose of
the _______ is not the longest nor the shortest conveying information? The purpose of a balanced modulator in an
radiating element. Amplitude modulation SSB transmitter is to:
driven element * suppress the carrier and pass on the two
In what emission type does the instantaneous sidebands *
Which list of emission types is in order from amplitude (envelope) of the RF signal vary in
the narrowest bandwidth to the widest accordance with the modulating audio? In a SSB transmission, the carrier is:
bandwidth? Amplitude modulation reinserted at the receiver *
CW, RTTY, SSB voice, FM voice
Morse code is usually transmitted by radio as: The automatic level control (ALC) in a SSB
The figure in a receiver's specifications which an interrupted carrier * transmitter:
indicates its sensitivity is the: controls the peak audio input so that the final
signal plus noise to noise ratio * A mismatched antenna or feedline may present amplifier is not overdriven *
an incorrect load to the transmitter. The result
If two receivers of different sensitivity are may be: What may happen if an FM transmitter is
compared, the less sensitive receiver will excessive heat produced in the final operated with the microphone gain or
produce: transmitter stage * deviation control set too high?
less signal or more noise * It may cause interference to other stations
One result of a slight mismatch between the operating near its frequency *
Which of the following modes of transmission power amplifier of a transmitter and the
is usually detected with a product detector? antenna would be: What may your FM hand-held or mobile
Single sideband suppressed carrier reduced antenna radiation * transceiver do if you shout into its
microphone?
A receiver designed for SSB reception must An RF oscillator should be electrically and It may cause interference to other stations
have a BFO (beat frequency oscillator) mechanically stable. This is to ensure that the operating near its frequency
because: oscillator does not:

2
Excel Review Center ECE Refresher/Coaching Course EST TH 1
What can you do if you are told your FM If a single-sideband phone transmitter is 100% How could you best keep unauthorized
hand-held or mobile transceiver is modulated, what will a speech processor do to persons from using your amateur station at
overdeviating? the transmitter's power? home?
Talk farther away from the microphone It will add nothing to the output PEP Use a key-operated on/off switch in the main
power line
What kind of emission would your FM When switching from receive to transmit:
transmitter produce if its microphone failed to the receiver should be muted * How could you best keep unauthorized
work? persons from using a mobile amateur station in
An unmodulated carrier A switching system to enable the use of one your car?
antenna for a transmitter and receiver should Disconnect the microphone when you are not
Why is FM voice best for local VHF/UHF also: using it
radio communications? disable the unit not being used *
It has high-fidelity audio which can be Why would you use a key- operated on/off
understood even when the signal is somewhat An antenna changeover switch in a switch in the main power line of your station?
weak transmitter-receiver combination is necessary: To keep unauthorized persons from using
so that one antenna can be used for your station
What is the usual bandwidth of a frequency- transmitter and receiver*
modulated amateur signal? Why would there be a switch in a high voltage
Between 10 and 20 kHz Which of the following components could be power supply to turn off the power if its
used as a dynamic microphone? cabinet is opened?
What is the result of overdeviation in an FM loudspeaker To keep anyone opening the cabinet from
transmitter? getting shocked by dangerous high voltages
Out-of-channel emissions What does "connected" mean in a packet-radio
link? How little electrical current flowing through
What emission is produced by a reactance A transmitting station is sending data to only the human body can be fatal?
modulator connected to an RF power one receiving station; it replies that the data As little as 1/10 of an ampere
amplifier? is being received correctly
Phase modulation Which body organ can be fatally affected by a
What does "monitoring" mean on a packet- very small amount of electrical current?
Why isn't frequency modulated (FM) phone radio frequency? The heart
used below 29.5 MHz? A receiving station is displaying messages
The bandwidth would exceed limits in the that may not be sent to it, and is not replying What is the minimum voltage which is usually
Regulations to any message dangerous to humans?
30 volts
You are transmitting FM on the 2 metre band. What is a digipeater?
Several stations advise you that your A packet-radio station that retransmits only What should you do if you discover someone
transmission is distorted. A quick check with a data that is marked to be retransmitted who is being burned by high voltage?
frequency counter tells you that the transmitter Turn off the power, call for emergency help
is on the proper frequency. Which of the What does "network" mean in packet radio? and give CPR if needed
following is the most probable cause of the A way of connecting packet-radio stations so
distortion? data can be sent over long distances What is the safest method to remove an
The frequency deviation of your transmitter unconscious person from contact with a high
is set too high * In packet-radio operation, what equipment voltage source?
connects to a terminal-node controller? Turn off the high voltage switch before
FM receivers perform in an unusual manner A transceiver and a terminal or computer removing the person from contact with the
when two or more stations are present. The system source
loudest signal, even though it is only two or
three times as loud as the other signals, will be How would you modulate a 2 meter FM Before checking a fault in a mains operated
the only transmission demodulated. This is transceiver to produce packet-radio emissions? power supply unit, it would be safest to First:
called: Connect a terminal-node controller to the turn off the power and remove power plug *
capture effect * transceiver's microphone input
Fault finding in a power supply of an amateur
What do many amateurs use to help form good When selecting a RTTY transmitting transmitter while the supply is operating is not
Morse code characters? frequency, what minimum frequency a recommended technique because of the risk
An electronic keyer separation from a contact in progress should of:
you allow (center to center) to minimize electric shock *
Where would you connect a microphone for interference?
voice operation? 250 to 500 Hz For best protection from electrical shock, what
To a transceiver should be grounded in an amateur station?
Digital transmissions use signals called All station equipment
What would you connect to a transceiver for _______ to transmit the states 1 and 0.
voice operation? mark and space * If a separate ground system is not possible for
A microphone your amateur station, an alternative indoor
Which of the following terms does not apply grounding point could be:
Why might a dummy antenna get warm when to packet? a metallic cold water pipe *
in use? Baudot
Because it changes RF energy into heat To protect you against electrical shock, the
When using AMTOR transmissions, there are chassis of each piece of your station equipment
What is the circuit called which causes a two modes that may be utilized. Mode A uses should be connected to:
transmitter to automatically transmit when an Automatic Repeat Request (ARQ) protocol a good ground connection *
operator speaks into its microphone? and is normally used:
VOX for communications after contact has been Which of these materials is best for a ground
established * rod driven into the earth?
What is the reason for using a properly Copper-clad steel
adjusted speech processor with a single What is the most common data rate used for
sideband phone transmitter? VHF packet communications? Where should the green wire in a three wire
It improves signal intelligibility at the 1200 baud AC line cord be connected in a power supply?
receiver To the chassis

3
Excel Review Center ECE Refresher/Coaching Course EST TH 1
What is one good way to avoid stray RF What safety precautions should you take The characteristic impedance of a 20 metre
energy in your amateur station? before beginning repairs on an antenna? piece of transmission line is 52 ohms. If 10
Keep the station's ground wire as short as Be sure to turn off the transmitter and metres were cut off, the impedance would be:
possible disconnect the feed line * 52 ohms

If your third-floor amateur station has a ground What precaution should you take when The impedance of a coaxial line:
wire running 10.05 metres (33 feet) down to a installing a ground-mounted antenna? can be the same for different diameter line *
ground rod, why might you get an RF burn if It should be installed so no one can come in
you touch the front panel of your HF contact with it* What commonly available antenna feed line
transceiver? can be buried directly in the ground for some
Because the ground wire is a resonant length What should you do for safety when operating distance without adverse effects?
on several HF bands and acts more like an at 1270 MHz? coaxial cable *
antenna than an RF ground connection * Keep antenna away from your eyes when RF
is applied The characteristic impedance of a transmission
Which statement about station grounding is line is:
true? What should you do for safety if you put up a equal to the pure resistance which, if
RF hot spots can occur in a station located UHF transmitting antenna? connected to the end of the line, will absorb
above the ground floor if the equipment is Make sure the antenna will be in a place all the power arriving along it *
grounded by a long ground wire where no one can get near it when you are
transmitting A transmission line differs from an ordinary
On mains operated power supplies, the ground circuit or network in communications or
wire should be connected to the metal chassis What should you do for safety, before signaling devices in one very important way.
of the power supply. This ensures, in case removing the shielding on a UHF power That important aspect is:
there is a fault in the power supply, that the amplifier? propagation delay *
chassis: Make sure the amplifier cannot accidentally
does not develop a high voltage with respect be turned on The characteristic impedance of a parallel wire
to the ground* transmission line does not depend on the:
Why should you make sure the antenna of a velocity of energy on the line *
The purpose of using a three- wire power cord hand-held transceiver is not close to your head
and plug on amateur radio equipment is to: when transmitting? Any length of transmission line may be made
prevent the chassis from becoming live in To reduce your exposure to the to appear as an infinitely long line by:
case of an internal short to the chassis * radiofrequency energy terminating the line in its characteristic
impedance *
Why should you ground all antenna and rotator How should you position the antenna of a
cables when your amateur station is not in use? hand-held transceiver while you are What factors determine the characteristic
To protect the station and building from transmitting? impedance of a parallel-conductor antenna
lightning damage * Away from your head and away from others feed line?
* The distance between the centres of the
How can an antenna system be protected from How can exposure to a large amount of RF conductors and the radius of the conductors *
lightning damage? energy affect body tissue?
Ground all antennas when they are not in use It heats the tissue What factors determine the characteristic
impedance of a coaxial antenna feed line?
How can amateur station equipment best be Which body organ is the most likely to be The ratio f the diameter of the inner
protected from lightning damage? damaged from the heating effects of RF conductor to the diameter of the braid
Disconnect all equipment from the power radiation?
lines and antenna cables Eyes What is a coaxial cable?
A center wire inside an insulating material
What equipment should be worn for working Depending on the wavelength of the signal, the which is covered by a metal sleeve or shield
on an antenna tower? energy density of the RF field, and other
Approved equipment in accordance with factors, in what way can RF energy affect What is parallel-conductor feed line?
provincial safety standards concerning body tissue? Two wires side-by-side held apart by
climbing It heats the tissue insulating rods *

Why should you wear a safety belt if you are If you operate your amateur station with What kind of antenna feed line is made of two
working on an antenna tower? indoor antennas, what precautions should you conductors held apart by insulated rods?
To prevent you from accidentally falling take when you install them? Open-conductor ladder line
Locate the antennas as far away as possible
For safety, how high should you place a from living spaces that will be occupied while What does the term "balun" mean?
horizontal wire antenna? you are operating * Balanced to unbalanced
High enough so that no one can touch any
part of it from the ground Why should directional high- gain antennas be Where would you install a balun to feed a
mounted higher than nearby structures? dipole antenna with 50-ohm coaxial cable?
Why should you wear a hard hat if you are on So they will not direct RF energy toward Between the coaxial cable and the antenna
the ground helping someone work on an people in nearby structures
antenna tower? What is an unbalanced line?
To protect your head from something For best RF safety, where should the ends and Feed line with one conductor connected to
dropped from the tower center of a dipole antenna be located? ground
As high as possible to prevent people from
Why should your outside antennas be high coming in contact with the antenna What device can be installed to feed a
enough so that no one can touch them while balanced antenna with an unbalanced feed
you are transmitting? What connects your transceiver to your line?
Touching the antenna might cause RF burns antenna? A balun
* A feed line
Why should you make sure that no one can A flexible coaxial line contains:
touch an open-wire feed line while you are The characteristic impedance of a transmission braid and insulation around a central
transmitting with it? line is determined by the: conductor *
Because high-voltage radio energy might physical dimensions and relative positions of
burn the person the conductors * A balanced transmission line:
is made of two parallel wires *

4
Excel Review Center ECE Refresher/Coaching Course EST TH 1
A 75 ohm transmission line could be matched As the frequency of a signal is changed, what It matches a transceiver to a mismatched
to the 300 ohm feedpoint of an antenna: happens to signal loss in a feed line? antenna system*
by using a 4 to 1 balun * Signal loss increases with increasing
frequency What would you use to connect a coaxial cable
What kind of antenna feed line can be of 50 ohms impedance to an antenna of 35
constructed using two conductors which are Losses occurring on a transmission line ohms impedance?
maintained a uniform distance apart using between transmitter and antenna results in: An impedance-matching device
insulated spreaders? less RF power being radiated *
600 ohm open-wire When will a power source deliver maximum
The lowest loss feed line on HF is: output to the load?
Why does coaxial cable make a good antenna open-wire When the impedance of the load is equal to
feed line? the impedance of the source
It is weatherproof, and its impedance matches In what values are RF feed line losses
most amateur antennas expressed? What happens when the impedance of an
dB per unit length * electrical load is equal to the internal
What is the best antenna feed line to use, if it impedance of the power source?
must be put near grounded metal objects? If the length of coaxial feed line is increased The source delivers maximum power to the
Coaxial cable from 20 metres (65.6 ft) to 40 metres (131.2 load
ft), how would this affect the line loss?
What are some reasons not to use parallel- It would be increased by 100% Why is impedance matching important?
conductor feed line? So the source can deliver maximum power to
It does not work well when tied down to metal If the frequency is increased, how would this the load *
objects, and you must use an impedance- affect the loss on a transmission line?
matching device with your transceiver It would increase To obtain efficient power transmission from a
transmitter to an antenna requires:
What common connector usually joins RG-213 What does an SWR reading of 1:1 mean? matching of impedances *
coaxial cable to an HF transceiver? The best impedance match has been attained
A PL-259 connector To obtain efficient transfer of power from a
What does an SWR reading of less than 1.5:1 transmitter to an antenna, it is important that
What common connector usually joins a hand- mean? there is a:
held transceiver to its antenna? A fairly good impedance match matching of impedance *
A BNC connector
What kind of SWR reading may mean poor If an antenna is correctly matched to a
Which of these common connectors has the electrical contact between parts of an antenna transmitter, the length of transmission line:
lowest loss at UHF? system? will have no effect on the matching *
A type-N connector A jumpy reading
The reason that an RF transmission line should
If you install a 6 metre Yagi antenna on a What does a very high SWR reading mean? be matched at the transmitter end is to:
tower 50 metres from your transmitter, which The antenna is the wrong length, or there transfer the maximum amount of power to
of the following feed lines is best? may be an open or shorted connection the antenna *
RG-213 somewhere in the feed line *
If the centre impedance of a folded dipole is
Why should you regularly clean, tighten and What does standing-wave ratio mean? approximately 300 ohms, and you are using
re-solder all antenna connectors? The ratio of maximum to minimum voltages RG8U (50 ohms) coaxial lines, what is the
To help keep their resistance at a minimum on a feed line* ratio required to have the line and the antenna
matched?
What commonly available antenna feed line If your antenna feed line gets hot when you are 6:1 *
can be buried directly in the ground for some transmitting, what might this mean?
distance without adverse effects? The SWR may be too high, or the feed line What does horizontal wave polarization mean?
Coaxial cable loss may be high The electric lines of force of a radio wave are
parallel to the earth's surface
When antenna feed lines must be placed near If the characteristic impedance of the feedline
grounded metal objects, which of the does not match the antenna input impedance What does vertical wave polarization mean?
following feed lines should be used? then: The electric lines of force of a radio wave are
Coaxial cable standing waves are produced in the feedline perpendicular to the earth's surface
*
TV twin-lead feed line can be used for a feed The result of the presence of standing waves What electromagnetic wave polarization does
line in an amateur station. The impedance of on a transmission line is: a Yagi antenna have when its elements are
this line is approximately: reduced transfer of RF energy to the antenna parallel to the earth's surface?
300 ohms * Horizontal
An SWR meter measures the degree of match
Why should you use only good quality coaxial between transmission line and antenna by: What electromagnetic wave polarization does
cable and connectors for a UHF antenna comparing forward and reflected voltage * a half-wavelength antenna have when it is
system? perpendicular to the earth's surface?
To keep RF loss low A resonant antenna having a feed point Vertical
impedance of 200 ohms is connected to a feed
What are some reasons to use parallel line and transmitter which have an impedance Polarization of an antenna is determined by:
conductor feed line? of 50 ohms. What will the standing wave ratio the electric field *
It will operate with a high SWR, and has less of this system be?
loss than coaxial cable 4:1 An isotropic antenna is a:
hypothetical point source *
If your transmitter and antenna are 15 metres The type of feed line best suited to operating at
apart, but are connected by 65 metres of RG- a high standing wave ratio is: What is the antenna radiation pattern for an
58 coaxial cable, what should be done to 600 ohm open-wire isotropic radiator?
reduce feed line loss? A sphere
Shorten the excess cable What device might allow use of an antenna on
a band it was not designed for? VHF signals from a mobile station using a
As the length of a feed line is changed, what An antenna tuner vertical whip antenna will normally be best
happens to signal loss? received using a:
Signal loss increases as length increases What does an antenna matching unit do? vertical ground-plane antenna *

5
Excel Review Center ECE Refresher/Coaching Course EST TH 1
A dipole antenna will emit a vertically The property of an antenna, which defines the Why is a loading coil often used with an HF
polarized wave if it is: range of frequencies to which it will respond, mobile vertical antenna?
mounted vertically * is called its: To tune out capacitive reactance
Bandwidth
If an electromagnetic wave leaves an antenna What is the main reason why so many VHF
vertically polarized, it will arrive at the Approximately how much gain does a half- base and mobile antennas are 5/8 of a
receiving antenna, by ground wave: wave dipole have over an isotropic radiator? wavelength?
vertically polarized * 2.1 dB The angle of radiation is low

Compared with a horizontal antenna, a vertical What is meant by antenna gain? How many directly driven elements do most
antenna will receive a vertically polarized The numerical ratio relating the radiated Yagi antennas have?
radio wave: signal strength of an antenna to that of One
at greater strength * another antenna
Approximately how long is the driven element
If an antenna is made longer, what happens to What is meant by antenna bandwidth? of a Yagi antenna for 14.0 MHz?
its resonant frequency? The frequency range over which the antenna 10.21 metres (33 feet and 6 inches)
It decreases may be expected to perform well
Approximately how long is the director
If an antenna is made shorter, what happens to In free space, what is the radiation element of a Yagi antenna for 21.1 MHz?
its resonant frequency? characteristic of a half-wave dipole? 6.4 metres (21 feet)
It increases Minimum radiation from the ends, maximum
broadside * Approximately how long is the reflector
The wavelength for a frequency of 25 MHz is: element of a Yagi antenna for 28.1 MHz?
12 metres (39.4 ft) * The gain of an antenna, especially on VHF and 5.33 metres (17.5 feet)
above, is quoted in dBi. The "i" in this
The velocity of propagation of radio frequency expression stands for: What is one effect of increasing the boom
energy in free space is: Isotropic length and adding directors to a Yagi antenna?
300 000 kilometres per second Gain increases
The front-to-back ratio of a beam antenna is:
Adding a series inductance to an antenna the ratio of the maximum forward power in What are some advantages of a Yagi with wide
would: the major lobe to the maximum backward element spacing?
decrease the resonant frequency * power radiation * High gain, less critical tuning and wider
bandwidth
The resonant frequency of an antenna may be How do you calculate the length in metres
increased by: (feet) of a quarter-wavelength vertical Why is a Yagi antenna often used for
shortening the radiating element * antenna? radiocommunications on the 20-metre band?
Divide 71.5 (234) by the antenna's operating It helps reduce interference from other
The speed of a radio wave: frequency (in MHz) stations off to the side or behind
is the same as the speed of light *
If you made a quarter-wavelength vertical What does "antenna front-to- back ratio" mean
At the end of suspended antenna wire, antenna for 21.125 MHz, how long would it in reference to a Yagi antenna?
insulators are used. These act to: be? The power radiated in the major radiation
limit the electrical length of the antenna * 3.36 metres (11.0 ft) lobe compared to the power radiated in
exactly the opposite direction *
To lower the resonant frequency of an antenna, If you made a half-wavelength vertical antenna
the operator should: for 223 MHz, how long would it be? What is a good way to get maximum
lengthen it * 64 cm (25.2 in) performance from a Yagi antenna?
Optimize the lengths and spacing of the
One solution to multiband operation with a Why is a 5/8-wavelength vertical antenna elements
shortened radiator is the "trap dipole" or trap better than a 1/4-wavelength vertical antenna
vertical. These "traps" are actually: for VHF or UHF mobile operations? The spacing between the elements on a three-
a coil and capacitor in parallel * A 5/8-wavelength antenna has more gain * element Yagi antenna, representing the best
overall choice, is _______ of a wavelength.
The wavelength corresponding to a frequency If a magnetic-base whip antenna is placed on 0.2
of 2 MHz is: the roof of a car, in what direction does it send
150 m (492 ft) out radio energy? If the forward gain of a six- element Yagi is
It goes out equally well in all horizontal about 10 dB, what would the gain of two of
What is a parasitic beam antenna? directions these antennas be if they were "stacked"?
An antenna where some elements obtain their 13 dB
radio energy by induction or radiation from a What is an advantage of downward sloping
driven element * radials on a ground plane antenna? If you made a half-wavelength dipole antenna
It brings the feed point impedance closer to for 28.550 MHz, how long would it be?
How can the bandwidth of a parasitic beam 50 ohms 10.16 metres (33.26 ft)
antenna be increased?
Use larger diameter elements What happens to the feed point impedance of a What is one disadvantage of a random wire
ground-plane antenna when its radials are antenna?
If a slightly shorter parasitic element is placed changed from horizontal to downward- You may experience RF feedback in your
0.1 wavelength away from an HF dipole sloping? station
antenna, what effect will this have on the It increases
antenna's radiation pattern? What is the low angle radiation pattern of an
A major lobe will develop in the horizontal Which of the following transmission lines will ideal half-wavelength dipole HF antenna
plane, toward the parasitic element give the best match to the base of a quarter- installed parallel to the earth?
wave ground-plane antenna? It is a figure-eight, perpendicular to the
If a slightly longer parasitic element is placed 50 ohms coaxial cable antenna
0.1 wavelength away from an HF dipole
antenna, what effect will this have on the The main characteristic of a vertical antenna is The impedances in ohms at the feed point of
antenna's radiation pattern? that it will: the dipole and folded dipole are, respectively:
A major lobe will develop in the horizontal receive signals equally well from all compass 73 and 300
plane, away from the parasitic element, points around it *
toward the dipole

6
Excel Review Center ECE Refresher/Coaching Course EST TH 1
A dipole transmitting antenna, placed so that overall length of the driven element is During the day, one of the ionospheric layers
the ends are pointing North/South, radiates: approximately: splits into two parts called:
mostly to the East and West * one wavelength * F1 & F2

How does the bandwidth of a folded dipole What type of propagation usually occurs from The position of the E layer in the ionosphere
antenna compare with that of a simple dipole one hand- held VHF transceiver to another is:
antenna? nearby? below the F layer *
It is greater * Line-of-sight propagation
What is a skip zone?
What is a disadvantage of using an antenna How does the range of sky-wave propagation An area which is too far away for ground-
equipped with traps? compare to ground- wave propagation? wave propagation, but too close for sky-wave
It will radiate harmonics It is much longer propagation *

What is an advantage of using a trap antenna? When a signal is returned to earth by the What is the maximum distance along the
It may be used for multi- band operation ionosphere, what is this called? earth's surface that is normally covered in one
Sky-wave propagation hop using the F2 region?
The "doublet antenna" is the most common in 4500km (2500 miles)
the amateur service. If you were to cut this How are VHF signals propagated within the
antenna for 3.75 MHz, what would be its range of the visible horizon? What is the maximum distance along the
approximate length? By direct wave earth's surface that is normally covered in one
38 meters (125 ft.) * hop using the E region?
Skywave is another name for: 2160 km (1200 miles)
What is a cubical quad antenna? ionospheric wave *
Two or more parallel four- sided wire loops, Skip zone is:
each approximately one-electrical wavelength That portion of the radiation which is directly a zone between the end of the ground wave
long affected by the surface of the earth is called: and the point where the first refracted wave
ground wave * returns to earth *
What is a delta loop antenna?
A type of cubical quad antenna, except with At HF frequencies, line-of-sight transmission The distance to Europe from your location is
triangular elements rather than square between two stations uses mainly the: approximately 5000 km. What sort of
ground wave * propagation is the most likely to be involved?
Approximately how long is each side of a multihop
cubical quad antenna driven element for 21.4 The distance travelled by ground waves:
MHz? is less at higher frequencies * For radio signals, the skip distance is
3.54 metres (11.7 feet) * determined by the:
The radio wave which follows a path from the height of the ionosphere and the angle of
Approximately how long is each side of a transmitter to the ionosphere and back to earth radiation *
cubical quad antenna driven element for 14.3 is known correctly as the:
MHz? ionospheric wave * The distance from the transmitter to the nearest
5.36 metres (17.6 feet) point where the sky wave returns to the earth is
What causes the ionosphere to form? called the:
Approximately how long is each leg of a Solar radiation ionizing the outer atmosphere skip distance *
symmetrical delta loop antenna driven element *
for 28.7 MHz? Reception of high frequency (HF) radio waves Skip distance is the:
3.5 metres (11.5 feet) beyond 4000 km is generally possible by: the minimum distance reached by a signal
ionospheric wave * after one reflection by the ionosphere *
Which statement about two- element delta
loops and quad antennas is true? What type of solar radiation is most Skip distance is a term associated with signals
They compare favorably with a three element responsible for ionization in the outer from the ionosphere. Skip effects are due to:
Yagi atmosphere? reflection and refraction from the ionosphere
Ultraviolet *
Compared to a dipole antenna, what are the The skip distance of a sky wave will be
directional radiation characteristics of a Which ionospheric region is closest to the greatest when the:
cubical quad antenna? earth? angle between ground and radiation is
The quad has more directivity in both The D region smallest *
horizontal and vertical planes
Which region of the ionosphere is the least If the height of the reflecting layer of the
Moving the feed point of a multielement quad useful for long distance radio-wave ionosphere increases, the skip distance of a
antenna from a side parallel to the ground to a propagation? high frequency (HF) transmission:
side perpendicular to the ground will have The D region becomes greater *
what effect?
It will change the antenna polarization from What two sub-regions of ionosphere exist only What effect does the D region of the
horizontal to vertical in the daytime? ionosphere have on lower frequency HF
F1 and F2 signals in the daytime?
What does the term "antenna front-to-back It absorbs the signals
ratio" mean in reference to a delta loop When is the ionosphere most ionized?
antenna? Midday What causes the ionosphere to absorb radio
The power radiated in the major radiation waves?
lobe compared to the power radiated in When is the ionosphere least ionized? The ionization of the D region
exactly the opposite direction * Shortly before dawn
Two or more parts of the radio wave follow
The cubical "quad" or "quad" antenna consists Why is the F2 region mainly responsible for different paths during propagation and this
of two or more square loops of wire. The the longest distance radio-wave propagation? may result in phase differences at the receiver.
driven element has an approximate overall Because it is the lowest ionospheric region This "change" at the receiver is called:
length of: Fading
one wavelength * What is the main reason the 160, 80 and 40
metre amateur bands tend to be useful only for A change or variation in signal strength at the
The delta loop antenna consists of two or more short-distance communications during daylight antenna, caused by differences in path lengths,
triangular structures mounted on a boom. The hours? is called:
Because of D-region absorption fading

7
Excel Review Center ECE Refresher/Coaching Course EST TH 1
When a transmitted radio signal reaches a What happens to signals higher in frequency On which amateur frequency band is the
station by a one-hop and two-hop skip path, than the critical frequency? extended-distance propagation effect of
small changes in the ionosphere can cause: They pass through the ionosphere sporadic-E most often observed?
variations in signal strength * 6 metres
What causes the maximum usable frequency to
The usual effect of ionospheric storms is to: vary? In the northern hemisphere, in which direction
cause a fade-out of sky- wave signals * The amount of radiation received from the should a directional antenna be pointed to take
sun, mainly ultraviolet maximum advantage of auroral propagation?
On the VHF and UHF bands, polarization of North
the receiving antenna is very important in What does maximum usable frequency mean?
relation to the transmitting antenna, yet on HF The highest frequency signal that will reach Where in the ionosphere does auroral activity
bands it is relatively unimportant. Why is that its intended destination occur?
so? At E-region height
The ionosphere can change the polarization What can be done at an amateur station to
of the signal from moment to moment continue HF communications during a sudden Which emission modes are best for auroral
ionospheric disturbance? propagation?
What causes selective fading? Try a higher frequency CW and SSB
Phase differences between radio wave
components of the same transmission, as What is one way to determine if the maximum Excluding enhanced propagation modes, what
experienced at the receiving station usable frequency (MUF) is high enough to is the approximate range of normal VHF
support 28 MHz propagation between your tropospheric propagation?
How does the bandwidth of a transmitted station and western Europe? 800 km (500 miles)
signal affect selective fading? Listen for signals on the 10-metre beacon
It is more pronounced at wide bandwidths frequency * What effect is responsible for propagating a
VHF signal over
Polarization change often takes place on radio What usually happens to radio waves with 800 km (500 miles)?
waves that are propagated over long distances. frequencies below the maximum usable Tropospheric ducting
Which of these does not cause polarization frequency (MUF) when they are sent into the
change? ionosphere? What kind of propagation would best be used
Parabolic interaction They are bent back to the earth by two stations within each other's skip zone
on a certain frequency?
Reflection of a SSB transmission from the At what point in the solar cycle does the 20- Ground-wave
ionosphere causes: metre band usually support worldwide
little or no phase-shift distortion * propagation during daylight hours? If you receive a weak, distorted signal from a
At any point in the solar cycle distance, and close to the maximum usable
How do sunspots change the ionization of the frequency, what type of propagation is
atmosphere? If we transmit a signal, the frequency of which probably occurring?
The more sunspots there are, the greater the is so high we no longer receive a reflection Scatter
ionization * from the ionosphere, the signal frequency is
above the: What is a characteristic of HF scatter signals?
How long is an average sunspot cycle? maximum usable frequency * A wavering sound
11 years
Communication on the 80 metre band is What makes HF scatter signals often sound
What is solar flux? generally most difficult during: distorted?
The radio energy emitted by the sun daytime in summer * Energy scattered into the skip zone through
several radio-wave paths
What is the solar-flux index? The optimum working frequency provides the
A measure of solar activity that is taken at a best long range HF communication. Compared Why are HF scatter signals usually weak?
specific frequency with the maximum usable frequency (MUF), it Only a small part of the signal energy is
is usually: scattered into the skip zone
What influences all radiocommunication slightly lower *
beyond ground-wave or line-of-sight ranges? What type of radio-wave propagation allows a
Solar activity During summer daytime, which bands are the signal to be detected at a distance too far for
most difficult for communications beyond ground-wave propagation but too near for
Which two types of radiation from the sun ground wave? normal skywave propagation?
influence propagation? 160 and 80 metres * Scatter
Electromagnetic and particle emissions
Which ionospheric region most affects sky- When does scatter propagation on the HF
When sunspot numbers are high, how is the wave propagation on the 6 metre band? bands most often occur?
ionosphere affected? The E region * When communicating on frequencies above
Frequencies up to 40 MHz or higher are the maximum usable frequency (MUF)
normally usable for long-distance What effect does tropospheric bending have on
communication 2-metre radio waves? Which of the following is not a scatter mode?
It lets you contact stations farther away Absorption scatter
All communication frequencies throughout the
spectrum are affected in varying degrees by What causes tropospheric ducting of radio Meteor scatter is most effective on what band?
the: waves? 6 metres
sun A temperature inversion
Which of the following is not a scatter mode?
Average duration of a solar cycle is: That portion of the radiation kept close to the Inverted scatter
11 years earth's surface due to bending in the
atmosphere is called the: In which frequency range is meteor scatter
The ability of the ionosphere to reflect high tropospheric wave * most effective for extended-range
frequency radio signals depends on: communication?
the amount of solar radiation * What is a sporadic-E condition? 30 - 100 MHz
Patches of dense ionization at E-region
Propagation cycles have a period of height What is meant by receiver overload?
approximately 11: Interference caused by strong signals from a
Years nearby transmitter

8
Excel Review Center ECE Refresher/Coaching Course EST TH 1
What is one way to tell if radio frequency An amateur transmitter is being heard across transmit on 15 metres, what is probably the
interference to a receiver is caused by front- the entire dial of a broadcast receiver. The cause of the interference?
end overload? receiver is most probably suffering from: Harmonic radiation from your transmitter *
If the interference is about the same no cross-modulation or audio rectification in the
matter what frequency is used for the receiver * What is meant by harmonic radiation?
transmitter Unwanted signals at frequencies which are
Cross-modulation is usually caused by: multiples of the fundamental (chosen)
If a neighbour reports television interference rectification of strong signals * frequency *
whenever you transmit, no matter what band
you use, what is probably the cause of the What device can be used to minimize the Why is harmonic radiation from an amateur
interference? effect of RF pickup by audio wires connected station not wanted?
Receiver overload to stereo speakers, intercom amplifiers, It may cause interference to other stations
telephones, etc.? and may result in out-of-band signals *
What type of filter should be connected to a Ferrite core
TV receiver as the first step in trying to What type of interference may come from a
prevent RF overload from an amateur HF Stereo speaker leads often act as antennas to multi-band antenna connected to a poorly
station transmission? pick up RF signals. What is one method you tuned transmitter?
High-pass can use to minimize this effect? Harmonic radiation *
Shorten the leads
When the signal from a transmitter overloads If you are told your station was heard on 21
the audio stages of a broadcast receiver, the One method of preventing RF from entering a 375 kHz, but at the time you were operating on
transmitted signal: stereo set through the speaker leads is to wrap 7125 kHz, what is one reason this could
can appear wherever the receiver is tuned * each of the speaker leads around a: happen?
ferrite core * Your transmitter was radiating harmonic
Cross-modulation of a broadcast receiver by a signals
nearby transmitter would be noticed in the Stereo amplifiers often have long leads which
receiver as: pick up transmitted signals because they act as: What causes splatter interference?
the undesired signal in the background of the receiving antennas * Overmodulation of a transmitter
desired signal*
How can you prevent key-clicks? Your amateur radio transmitter appears to be
What is cross-modulation interference? By using a key-click filter creating interference to the television on
Modulation from an unwanted signal is channel 3 (60-66 MHz) when you are
heard in addition to the desired signal If someone tells you that signals from your transmitting on the 15 metre band. Other
hand-held transceiver are interfering with other channels are not affected. The most likely
What is the term used to refer to the condition signals on a frequency near yours, what may cause is:
where the signals from a very strong station be the cause? harmonic radiation from the transmitter *
are superimposed on other signals being Your hand-held may be transmitting spurious
received? emissions * One possible cause of TV interference by
Cross-modulation interference harmonics from an SSB transmitter is from
If your transmitter sends signals outside the "flat topping" — driving the final amplifier
What is the result of cross-modulation? band where it is transmitting, what is this into non- linear operation. The most
The modulation of an unwanted signal is called? appropriate remedy for this is:
heard on the desired signal Spurious emissions * reduce microphone gain *

If a television receiver suffers from cross- What problem may occur if your transmitter is In a transmitter, excessive harmonics are
modulation when a nearby amateur transmitter operated without the cover and other shielding produced by:
is operating at 14 MHz, which of the following in place? overdriven stages *
cures might be effective? It may transmit spurious emissions
A high pass filter attached to the antenna An interfering signal from a transmitter is
input of the television In Morse code transmission, local RF found to have a frequency of 57 MHz (TV
interference (key-clicks) is produced by: Channel 2 is 54 - 60 MHz). This signal could
How can cross-modulation be reduced? the making and breaking of the circuit at the be the:
By installing a suitable filter at the receiver Morse key * second harmonic of a 10 metre transmission
*
What devices would you install to reduce or Key-clicks, heard from a Morse code Harmonics may be produced in the RF power
eliminate audio-frequency interference to transmitter at a distant receiver, are the result amplifier of a transmitter if:
home entertainment systems? of: excessive drive signal is applied to it *
Bypass capacitors too sharp rise and decay times of the carrier *
What type of filter might be connected to an
What should be done if a properly operating In a Morse code transmission, local RF amateur HF transmitter to cut down on
amateur station is the cause of interference to a interference (key-clicks) is produced by: harmonic radiation?
nearby telephone? poor shaping of the waveform * A low pass filter
Ask the telephone company to install RFI
filters Key-clicks can be suppressed by: Why do modern HF transmitters have a built-
inserting a choke and a capacitor at the key in low pass filter in their RF output circuits?
What sound is heard from a public address * To reduce harmonic radiation
system if audio rectification of a nearby single- A parasitic oscillation:
sideband phone transmission occurs? is an unwanted signal developed in a What circuit blocks RF energy above and
Distorted speech from the transmitter's transmitter * below a certain limit?
signals A band pass filter
Parasitic oscillations in the RF power amplifier
What sound is heard from a publicaddress stage of a transmitter may be found: What should be the impedance of a low pass
system if audio rectification of a nearby CW at high or low frequencies * filter as compared to the impedance of the
transmission occurs? transmission line into which it is inserted?
On-and-off humming or clicking Transmitter RF amplifiers can generate About the same *
parasitic oscillations:
How can you minimize the possibility of audio on either side of the transmitter frequency * To reduce energy from an HF transmitter
rectification of your transmitter's signals? getting into a television set, you would place a
By ensuring that all station equipment is If a neighbour reports television interference _______ as close to the TV as possible.
properly grounded* on one or two channels only when you high pass filter

9
Excel Review Center ECE Refresher/Coaching Course EST TH 1
In order to reduce the harmonic output of a
high frequency (HF) transmitter, which of the
following filters should be installed at the
transmitter?
Low pass

To reduce harmonic output from a transmitter,

A band pass filter will:

A band reject filter will:

A high pass filter would normally be fitted:

A low pass filter suitable for a high frequency

END

10