Canadian Basic Qualification pool, section B-003-021

Subelement B-003

B-003

Section B-003-021

B-003-021-001

What should you do for safety when operating at UHF and microwave frequencies?

A.
Make sure that an RF leakage filter is installed at the antenna feed point
B.
Never use a horizontally polarized antenna
Correct Answer
C.
Keep antenna away from your eyes when RF is applied
D.
Make sure the standing wave ratio is low before you conduct a test

B-003-021-001

RF energy can heat body tissue. 1000 MHz is generally considered to be the low end of the MICROWAVE spectrum. Microwave energy has long been known for its 'heating' effect ( think "microwave oven" ). Never point antennas at anyone. Never look into antennas. Disconnect transmission lines before working on antennas (to further reduce the odds of an error at the station exposing to RF).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-003-021-002

What should you do for safety if you put up a UHF transmitting antenna?

A.
Make sure that RF field screens are in place
B.
Make sure the antenna is near the ground to keep its RF energy pointing in the correct direction
C.
Make sure you connect an RF leakage filter at the antenna feed point
Correct Answer
D.
Make sure the antenna will be in a place where no one can get near it when you are transmitting

B-003-021-002

RF energy can heat body tissue. VHF and UHF frequencies present the greatest risk. Never point antennas at anyone. Never look into antennas. Disconnect transmission lines before working on antennas (to further reduce the odds of an error at the station exposing to RF).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-003-021-003

What should you do for safety, before removing the shielding on a UHF power amplifier?

Correct Answer
A.
Make sure the amplifier cannot accidentally be turned on
B.
Make sure that RF leakage filters are connected
C.
Make sure the amplifier output connector is grounded
D.
Make sure all RF screens are in place at the amplifier output connector

B-003-021-003

RF energy can heat body tissue. VHF and UHF frequencies present the greatest risk.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-003-021-004

Why should you make sure the antenna of a hand-held transceiver is not close to your head when transmitting?

A.
To keep static charges from building up
B.
To use your body to reflect the signal in one direction
Correct Answer
C.
To reduce your exposure to the radio frequency energy
D.
To help the antenna radiate energy equally in all directions

B-003-021-004

RF energy can heat body tissue. VHF and UHF frequencies present the greatest risk. 48 MHz to 300 MHz is the range of radio frequencies over which Health-Canada's "Safety Code 6" recommends the lowest exposure level.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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B-003-021-005

How should you position the antenna of a hand-held transceiver while you are transmitting?

A.
Pointed down to bounce the signal off the ground
B.
Pointed towards the station you are contacting
Correct Answer
C.
Away from your head and away from others
D.
Pointed at the horizon

B-003-021-005

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-003-021-006

How can exposure to a large amount of RF energy affect body tissue?

Correct Answer
A.
It heats the tissue
B.
It lowers blood pressure
C.
It restricts blood flow
D.
It paralyzes the tissue

B-003-021-006

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-003-021-007

Which body organ is the most likely to be damaged from the heating effects of RF radiation?

A.
Liver
B.
Hands
C.
Heart
Correct Answer
D.
Eyes

B-003-021-007

The inside of the eye is mostly liquid. Ever seen a cup of water brought to a boil in a microwave oven ? RF energy can heat body tissue. VHF and UHF frequencies present the greatest risk. 48 MHz to 300 MHz is the range of radio frequencies over which Health-Canada's "Safety Code 6" recommends the lowest exposure level. Keep antennas away from your head.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-003-021-008

How does the power density of an electromagnetic wave change as it propagates away from an antenna in free space?

A.
It decreases in inverse proportion to the distance
B.
It decreases linearly with the distance
Correct Answer
C.
It decreases as the square of the distance
D.
It decreases at a rate depending on ground absorption

B-003-021-008

For example, if the power density 1 metre away from an antenna is 4 watts / square metre, it will be down to 1 watt / square metre at a distance of 2 metres. At a distance of 10 metres, the power density will be 0.04 watts / square metre. This example is valid in free space where no reflection can focus energy. The lesson here is that distance is the best way to reduce exposure to radiofrequency.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-003-021-009

If you operate your station with indoor antennas, what precautions should you take when you install them?

A.
Position the antennas parallel to electrical power wires to take advantage of parasitic effects
Correct Answer
B.
Locate the antennas as far away as possible from living spaces that will be occupied while you are operating
C.
Locate the antennas close to your operating position to minimize transmission line length
D.
Position the antennas along the edge of a wall where it meets the floor or ceiling to reduce parasitic radiation

B-003-021-009

RF energy can heat body tissue. Keep the antennas away from people and use as little power as possible.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-003-021-010

Why should directional high-gain antennas be mounted higher than nearby structures?

Correct Answer
A.
So they will not direct RF energy toward people in nearby structures
B.
So they will not damage nearby structures with RF energy
C.
So they will receive more sky waves and fewer ground waves
D.
So static electricity buildup is minimized

B-003-021-010

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

B-003-021-011

For best RF safety, where should the ends and centre of a dipole antenna be located?

A.
As close to the transmitter as possible so RF energy will be concentrated near the transmitter
Correct Answer
B.
As high as possible to prevent people from coming in contact with the antenna
C.
Close to the ground so simple adjustments can be easily made without climbing a ladder
D.
Near or over moist ground so RF energy will be radiated away from the ground

B-003-021-011

Even at modest power, touching a radiating antenna or open-wire line can lead to 'RF burns'. Voltage is not the only factor, radio frequency reaches deep into the skin, potentially causing nasty burns.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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