Antennas And Feed Lines

Antenna Length and Frequencies

T61B02

Which component is used to radiate radio energy?

A. An antenna

B. An earth ground

C. A chassis ground

D. A potentiometer

T94A01

How do you calculate the length (in feet) of a half-wavelength dipole antenna?

A. Divide 150 by the antenna's operating frequency (in MHz) [150/f(in MHz)]

B. Divide 234 by the antenna's operating frequency (in MHz) [234/f (in MHz)]

C. Divide 300 by the antenna's operating frequency (in MHz) [300/f (in MHz)]

D. Divide 468 by the antenna's operating frequency (in MHz) [468/f (in MHz)]

T92A02

How do you calculate the length (in feet) of a quarter-wavelength vertical antenna?

A. Divide 150 by the antenna's operating frequency (in MHz) [150/f (in MHz)]

B. Divide 234 by the antenna's operating frequency (in MHz) [234/f (in MHz)]

C. Divide 300 by the antenna's operating frequency (in MHz) [300/f (in MHz)]

D. Divide 468 by the antenna's operating frequency (in MHz) [468/f (in MHz)]

T93A03

How long should you make a quarter-wavelength vertical antenna for 440 MHz (measured to the nearest inch)?

A. 12 inches

B. 9 inches

C. 6 inches

D. 3 inches

T91A04

How long should you make a quarter-wavelength vertical antenna for 28.450 MHz (measured to the nearest foot)?

A. 8 ft

B. 12 ft

C. 16 ft

D. 24 ft

T93A05

How long should you make a quarter-wavelength vertical antenna for 146 MHz (measured to the nearest inch)?

A. 112 inches

B. 50 inches

C. 19 inches

D. 12 inches

T91A06

If an antenna is made longer, what happens to its resonant frequency?

A. It decreases

B. It increases

C. It stays the same

D. It disappears

T91A08

How could you decrease the resonant frequency of a dipole antenna?

A. Lengthen the antenna

B. Shorten the antenna

C. Use less feed line

D. Use a smaller size feed line

T92A07

If an antenna is made shorter, what happens to its resonant frequency?

A. It decreases

B. It increases

C. It stays the same

D. It disappears

T92A09

How could you increase the resonant frequency of a dipole antenna?

A. Lengthen the antenna

B. Shorten the antenna

C. Use more feed line

D. Use a larger size feed line

Non-Directional Antennas

T94B07

What type of non-directional antenna is easy to make at home and works well outdoors?

A. A Yagi

B. A delta loop

C. A cubical quad

D. A ground plane

Directional Antennas

T93B01

What is a directional antenna?

A. An antenna that sends and receives radio energy equally well in all directions

B. An antenna that cannot send and receive radio energy by skywave or skip propagation

C. An antenna that sends and receives radio energy mainly in one direction

D. An antenna that uses a directional coupler to measure power transmitted

T23D09

Which type of antenna would be a good choice as part of a portable HF amateur station that could be set up in case of an emergency?

A. A three-element quad

B. A three-element Yagi

C. A dipole

D. A parabolic dish

T91B02

How is a Yagi antenna constructed?

A. Two or more straight, parallel elements are fixed in line with each other

B. Two or more square or circular loops are fixed in line with each other

C. Two or more square or circular loops are stacked inside each other

D. A straight element is fixed in the center of three or more elements that angle toward the ground

T92B03

How many directly driven elements do most parasitic beam antennas have?

A. None

B. One

C. Two

D. Three

T91B04

What is a parasitic beam antenna?

A. An antenna in which some elements obtain their radio energy by induction or radiation from a driven element

B. An antenna in which wave traps are used to magnetically couple the elements

C. An antenna in which all elements are driven by direct connection to the feed line

D. An antenna in which the driven element obtains its radio energy by induction or radiation from director elements

T94B05

What are the parasitic elements of a Yagi antenna?

A. The driven element and any reflectors

B. The director and the driven element

C. Only the reflectors (if any)

D. Any directors or any reflectors

T92B06

What is a cubical quad antenna?

A. Four straight, parallel elements in line with each other, each approximately 1/2-electrical wavelength long

B. Two or more parallel four-sided wire loops, each approximately one-electrical wavelength long

C. A vertical conductor 1/4-electrical wavelength high, fed at the bottom

D. A center-fed wire 1/2-electrical wavelength long

Multiband Antennas

T91A10

What is one advantage to using a multiband antenna?

A. You can operate on several bands with a single feed line

B. Multiband antennas always have high gain

C. You can transmit on several frequencies simultaneously

D. Multiband antennas offer poor harmonic suppression

T94A11

What is one disadvantage to using a multiband antenna?

A. It must always be used with a balun

B. It will always have low gain

C. It cannot handle high power

D. It can radiate unwanted harmonics

T74B11

What would you use to connect a dual-band antenna to a mobile transceiver which has separate VHF and UHF outputs?

A. A dual-needle SWR meter

B. A full-duplex phone patch

C. Twin high-pass filters

D. A duplexer

Antenna Polarization

T94B08

What electromagnetic-wave polarization does most man-made electrical noise have in the HF and VHF spectrum?

A. Horizontal

B. Left-hand circular

C. Right-hand circular

D. Vertical

Connecting the Antenna to the Transceiver

T74A02

What connects your transceiver to your antenna?

A. A dummy load

B. A ground wire

C. The power cord

D. A feed line

T72A01

What would you connect to your transceiver if you wanted to switch it between several antennas?

A. A terminal-node switch

B. An antenna switch

C. A telegraph key switch

D. A high-pass filter

Coaxial Cable

T92B11

Why does coaxial cable make a good antenna feed line?

A. You can make it at home, and its impedance matches most amateur antennas

B. It is weatherproof, and it can be used near metal objects

C. It is weatherproof, and its impedance is higher than that of most amateur antennas

D. It can be used near metal objects, and its impedance is higher than that of most amateur antennas

Balun

T91B10

Where would you install a balun to feed a dipole antenna with 50-ohm coaxial cable?

A. Between the coaxial cable and the antenna

B. Between the transmitter and the coaxial cable

C. Between the antenna and the ground

D. Between the coaxial cable and the ground

Standing Wave Ratio

T94B09

What does standing-wave ratio mean?

A. The ratio of maximum to minimum inductances on a feed line

B. The ratio of maximum to minimum capacitances on a feed line

C. The ratio of maximum to minimum impedances on a feed line

D. The ratio of maximum to minimum voltages on a feed line

T44B09

What instrument is used to measure the relative impedance match between an antenna and its feed line?

A. An ammeter

B. An ohmmeter

C. A voltmeter

D. An SWR meter

T73A07

In Figure N7-2, if block 1 is a transceiver and block 3 is an antenna switch, what is block 2?

A. A terminal-node switch

B. A dipole antenna

C. An SWR meter

D. A high-pass filter

T41B06

What does a very high SWR reading mean?

A. The antenna is the wrong length, or there may be an open or shorted connection somewhere in the feed line

B. The signals coming from the antenna are unusually strong, which means very good radio conditions

C. The transmitter is putting out more power than normal, showing that it is about to go bad

D. There is a large amount of solar radiation, which means very poor radio conditions

T42B11

What does an SWR reading of 1:1 mean?

A. An antenna for another frequency band is probably connected

B. The best impedance match has been attained

C. No power is going to the antenna

D. The SWR meter is broken

T43B05

What does an SWR reading of less than 1.5:1 mean?

A. An impedance match that is too low

B. An impedance mismatch; something may be wrong with the antenna system

C. A fairly good impedance match

D. An antenna gain of 1.5

T42B07

If an SWR reading at the low frequency end of an amateur band is 2.5:1, increasing to 5:1 at the high frequency end of the same band, what does this tell you about your 1/2-wavelength dipole antenna?

A. The antenna is broadbanded

B. The antenna is too long for operation on the band

C. The antenna is too short for operation on the band

D. The antenna is just right for operation on the band

T43B08

If an SWR reading at the low frequency end of an amateur band is 5:1, decreasing to 2.5:1 at the high frequency end of the same band, what does this tell you about your 1/2-wavelength dipole antenna?

A. The antenna is broadbanded

B. The antenna is too long for operation on the band

C. The antenna is too short for operation on the band

D. The antenna is just right for operation on the band

T43B10

If you use an SWR meter designed to operate on 3-30 MHz for VHF measurements, how accurate will its readings be?

A. They will not be accurate

B. They will be accurate enough to get by

C. If it properly calibrates to full scale in the set position, they may be accurate

D. They will be accurate providing the readings are multiplied by 4.5

Antenna Tuners

T71A04

What does an antenna tuner do?

A. It matches a transceiver output impedance to the antenna system impedance

B. It helps a receiver automatically tune in stations that are far away

C. It switches an antenna system to a transceiver when sending, and to a receiver when listening

D. It switches a transceiver between different kinds of antennas connected to one feed line

T72A08

In Figure N7-3, if block 1 is a transceiver and block 2 is an SWR meter, what is block 3?

A. An antenna switch

B. An antenna tuner

C. A key-click filter

D. A terminal-node controller

Wattmeters

T41C08

What does a directional wattmeter measure?

A. Forward and reflected power

B. The directional pattern of an antenna

C. The energy used by a transmitter

D. Thermal heating in a load resistor

T41C10

Why might you use a peak-reading RF wattmeter at your station?

A. To make sure your transmitter's output power is not higher than that authorized by your license class

B. To make sure your transmitter is not drawing too much power from the AC line

C. To make sure all your transmitter's power is being radiated by your antenna

D. To measure transmitter input and output power at the same time

T41C03

Where should an RF wattmeter be connected for the most accurate readings of transmitter output power?

A. At the transmitter output connector

B. At the antenna feed point

C. One-half wavelength from the transmitter output

D. One-half wavelength from the antenna feed point

T42C07

At what line impedance do most RF watt meters usually operate?

A. 25 ohms

B. 50 ohms

C. 100 ohms

D. 300 ohms

T42C09

If a directional RF wattmeter reads 90 watts forward power and 10 watts reflected power, what is the actual transmitter output power?

A. 10 watts

B. 80 watts

C. 90 watts

D. 100 watts

Dummy Antennas

T42A08

What device is used in place of an antenna during transmitter tests so that no signal is radiated?

A. An antenna matcher

B. A dummy antenna

C. A low-pass filter

D. A decoupling resistor

T41A09

Why would you use a dummy antenna?

A. For off-the-air transmitter testing

B. To reduce output power

C. To give comparative signal reports

D. To allow antenna tuning without causing interference

T22A04

How can on-the-air interference be minimized during a lengthy transmitter testing or loading-up procedure?

A. Choose an unoccupied frequency

B. Use a dummy load

C. Use a non-resonant antenna

D. Use a resonant antenna that requires no loading-up procedure

T72A05

In Figure N7-1, if block 1 is a transceiver and block 3 is a dummy antenna, what is block 2?

A. A terminal-node switch

B. An antenna switch

C. A telegraph key switch

D. A high-pass filter

T74A06

In Figure N7-1, if block 1 is a transceiver and block 2 is an antenna switch, what is block 3?

A. A terminal-node switch

B. An SWR meter

C. A telegraph key switch

D. A dummy antenna

T41A10

What minimum rating should a dummy antenna have for use with a 100 watt single-sideband phone transmitter?

A. 100 watts continuous

B. 141 watts continuous

C. 175 watts continuous

D. 200 watts continuous

T42A11

Would a 100 watt light bulb make a good dummy load for tuning a transceiver?

A. Yes; a light bulb behaves exactly like a dummy load

B. No; the impedance of the light bulb changes as the filament gets hot

C. No; the light bulb would act like an open circuit

D. No; the light bulb would act like a short circuit

Answer Key

The answer to each question is coded in the 3^rd position of the question number.

Example: The answer to question T42A11 is B.

T42A11

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1 = A

2 = B

3 = C

4 = D