Technician Class Questions Pool


SUBELEMENT T9 - Radio waves, propagation, and antennas - 3 exam questions - 3 groups



T9A - Antenna types - vertical, horizontal, concept of gain, common portable and mobile antennas, losses with short antennas, relationships between antenna length and frequency, dummy loads - 1 exam question

T9A01
What is a beam antenna?
A. An antenna built from metal I-beams
B. An antenna that transmits and receives equally well in all directions
C. An antenna that concentrates signals in one direction
D. An antenna that reverses the phase of received signals

T9A02
What is an antenna that consists of a single element mounted perpendicular to the Earth's surface?
A. A conical monopole
B. A horizontal antenna
C. A vertical antenna
D. A traveling wave antenna

T9A03
What type of antenna is a simple dipole mounted so the elements are parallel to the Earth's surface?
A. A ground wave antenna
B. A horizontal antenna
C. A rhombic antenna
D. A vertical antenna

T9A04
What is a disadvantage of the "rubber duck" antenna supplied with most hand held radio transceivers?
A. It does not transmit or receive as effectively as a full sized antenna
B. It is much more expensive than a standard antenna
C. If the rubber end cap is lost it will unravel very quickly
D. It transmits a circular polarized signal

T9A05
How does the physical size of half-wave dipole antenna change with operating frequency?
A. It becomes longer as the frequency increases
B. It must be made larger because it has to handle more power
C. It becomes shorter as the frequency increases
D. It becomes shorter as the frequency deceases

T9A06

What is the advantage of 5/8 wavelength over 1/4 wavelength vertical antennas?
A. They are easier to match to the feed line than other types
B. Their radiation pattern concentrates energy at lower angles
C. They pick up less noise
D. Their radiation pattern concentrates energy at higher angles

T9A07
What is the primary purpose of a dummy load?
A. It does not radiate interfering signals when making tests
B. It will prevent over-modulation of your transmitter
C. It keeps you from making mistakes while on the air
D. It is used for close in work to prevent overloads T9A08
What type of antennas are the quad, Yagi, and dish?
A. Antennas invented after 1985
B. Loop antennas
C. Directional or beam antennas
D. Antennas that are not permitted for amateur radio stations

T9A09
What is one type of antenna that offers good efficiency when operating mobile and can be easily installed or removed?
A. A microwave antenna
B. A quad antenna
C. A traveling wave antenna
D. A magnet mount vertical antenna

T9A10
What is a good reason not to use a "rubber duck" antenna inside your car?
A. Signals can be 10 to 20 times weaker than when you are outside of the vehicle
B. RF energy trapped inside the vehicle can distort your signal
C. You might cause a fire in the vehicle upholstery
D. The SWR might increase

T9A11
What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?
A. 112 inches
B. 50 inches
C. 19 inches
D. 12 inches

T9A12
What is the approximate length, in inches, of a 6-meter 1/2 wavelength wire dipole antenna?
A. 6 inches
B. 50 inches
C. 112 inches
D. 236 inches


T9B - Propagation, fading, multipath distortion, reflections, radio horizon, terrain blocking, wavelength vs. penetration, antenna orientation - 1 exam question

T9B01
Why are VHF/UHF signals not normally heard over long distances?
A. They are too weak to go very far
B. FCC regulations prohibit them from going more than 50 miles
C. VHF and UHF signals are usually not reflected by the ionosphere
D. They collide with trees and shrubbery and fade out

T9B02
What might be happening when we hear a VHF signal from long distances?
A. Signals are being reflected from outer space
B. Someone is playing a recording to us
C. Signals are being reflected by lightning storms in our area
D. A possible cause is sporadic E reflection from a layer in the ionosphere

T9B03
What is the most likely cause of sudden bursts of tones or fragments of different conversations that interfere with VHF or UHF signals?
A. The batteries in your transceiver are failing
B. Strong signals are overloading the receiver and causing undesired signals to be heard
C. The receiver is picking up low orbit satellites
D. A nearby broadcast station is having transmitter problems

T9B04
What is the radio horizon?
A. The point where radio signals between two points are blocked by the curvature of the Earth
B. The distance from the ground to a horizontally mounted antenna
C. The farthest point you can see when standing at the base of your antenna tower
D. The shortest distance between two points on the Earth's surface

T9B05
What should you do if a station reports that your signals were strong just a moment ago, but now they are weak or distorted?
A. Change the batteries in your radio to a different type
B. Speak more slowly so he can understand your better
C. Ask the other operator to adjust his squelch control
D. Try moving a few feet, random reflections may be causing multi- path distortion.

T9B06
Why do UHF signals often work better inside of buildings than VHF signals?
A. VHF signals lose power faster over distance
B. The shorter wavelength of UHF signals allows them to more easily penetrate urban areas and buildings
C. This is incorrect; VHF works better than UHF inside buildings
D. UHF antennas are more efficient than VHF antennas

T9B07
What is a good thing to remember when using your hand-held VHF or UHF radio to reach a distant repeater?
A. Speak as loudly as possible to help your signal go farther
B. Keep your transmissions short to conserve battery power
C. Keep the antenna as close to vertical as you can
D. Turn off the CTCSS tone

T9B08
What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?
A. The modulation sidebands might become inverted
B. Signals could be as much as 100 times weaker C. Signals have an echo effect on voices
D. Nothing significant will happen

T9B09
What might be a way to reach a distant repeater if buildings or obstructions are blocking the direct line of sight path?
A. Change from vertical to horizontal polarization
B. Try using a directional antenna to find a path that reflects signals to the repeater
C. Ask the repeater owners to repair their receiver
D. Transmit on the repeater output frequency

T9B10
What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting?
A. Flip-flopping
B. Picket fencing
C. Frequency shifting
D. Pulsing

T9B11
Why do VHF and UHF Radio signals usually travel about a third farther than the visual line of sight distance between 2 stations?
A. Radio signals move somewhat faster than the speed of light and travel farther in the same amount of time
B. Radio waves are not blocked by dust particles
C. The Earth seems less curved to radio waves than to light
D. Radio waves are blocked by dust particles


T9C - Feedlines types, losses vs. frequency, SWR concepts, measuring SWR, matching and power transfer, weather protection, feedline failure modes - 1 exam question

T9C01
What, in general terms, is standing wave ratio (SWR)?
A. A measure of how well a load is matched to a transmitter
B. The ratio of high to low impedance in a feed line
C. The transmitter efficiency ratio
D. An indication of the quality of your station ground connection

T9C02
What reading on a SWR meter indicates a perfect impedance match between the antenna and the feed line?
A. 2 to 1
B. 1 to 3
C. 1 to 1
D. 10 to 1

T9C03
What might be indicated by erratic changes in SWR readings?
A. The transmitter is being modulated
B. A loose connection in your antenna or feedline
C. The transmitter is being over modulated
D. Interference from other stations is distorting your signal

T9C04
What is the SWR value where the protection circuits in most solid-state transmitters begin to reduce transmitter power?
A. 2 to 1
B. 1 to 2
C. 6 to 1
D. 10 to 1

T9C05
What happens to the power lost in a feed line?
A. It increases the SWR
B. It comes back into your transmitter and could cause damage
C. It is converted into heat by losses in the line
D. It can cause distortion of your signal

T9C06
What instrument other than a SWR meter could you use to determine if your feedline and antenna are properly matched?
A. Voltmeter
B. Ohmmeter
C. Iambic pentameter
D. Directional wattmeter

T9C07
What is the most common reason for failure of coaxial cables?
A. Moisture contamination B. Gamma rays
C. End of service life
D. Overloading

T9C08
Why is it important to have a low SWR in an antenna system that uses coaxial cable feedline?
A. To reduce television interference
B. To allow the efficient transfer of power and reduce losses
C. To prolong antenna life
D. To keep your signal from changing polarization

T9C09
What can happen to older coaxial cables that are exposed to weather and sunlight for several years?
A. Nothing, weather and sunlight do not affect coaxial cable
B. The cable can shrink and break
C. Losses can increase dramatically
D. It will short-circuit

T9C10
Why is the outer sheath of most coaxial cables black in color?
A. It is the cheapest color to use
B. To see nicks and cracks in the cable
C. Black cables have less loss
D. Black provides protection against ultraviolet damage

T9C11
What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?
A. 8 Ohms
B. 50 Ohms
C. 600 Ohms
D. 12 Ohms

T9C12
Why is coaxial cable used more often than any other feed line for amateur radio antenna systems?
A. It is easy to use and requires few special installation
considerations

B. It has less loss than any other type of feedline
C. It can handle more power than any other type of feedline
D. It is less expensive than any other types of line

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