B-006-11: Yagi antennas - types, dimensions, characteristics
B-006-11-01:
How many directly driven elements do most Yagi antennas have?
One
None
Two
Three
B-006-11-02:
Approximately how long is the driven element of a Yagi antenna for 14.0 MHz?
10.21 metres (33 feet and 6 inches)
5.21 metres (17 feet)
10.67 metres (35 feet)
20.12 metres (66 feet)
B-006-11-03:
Approximately how long is the director element of a Yagi antenna for 21.1 MHz?
6.4 metres (21 feet)
5.18 metres (17 feet)
3.2 metres (10.5 feet)
12.8 metres (42 feet)
B-006-11-04:
Approximately how long is the reflector element of a Yagi antenna for 28.1 MHz?
5.33 metres (17.5 feet)
4.88 metres (16 feet)
10.67 metres (35 feet)
2.66 metres (8.75 feet)
B-006-11-05:
What is one effect of increasing the boom length and adding directors to a Yagi antenna?
Gain increases
SWR increases
Weight decreases
Wind load decreases
B-006-11-06:
What are some advantages of a Yagi with wide element spacing?
High gain, less critical tuning and wider bandwidth
High gain, lower loss and a low SWR
High front-to-back ratio and lower input resistance
Shorter boom length, lower weight and wind resistance
B-006-11-07:
Why is a Yagi antenna often used for radiocommunications on the 20-metre band?
It helps reduce interference from other stations off to the side or behind
It provides excellent omnidirectional coverage in the horizontal plane
It is smaller, less expensive and easier to erect than a dipole or vertical antenna
It provides the highest possible angle of radiation for the HF bands
B-006-11-08:
What does "antenna front-to-back ratio" mean in reference to a Yagi antenna?
The power radiated in the major radiation lobe compared to the power radiated in exactly the opposite direction
The relative position of the driven element with respect to the reflectors and directors
The power radiated in the major radiation lobe compared to the power radiated 90 degrees away from that direction
The number of directors versus the number of reflectors
B-006-11-09:
What is a good way to get maximum performance from a Yagi antenna?
Optimize the lengths and spacing of the elements
Use RG-58 feed line
Use a reactance bridge to measure the antenna performance from each direction around the antenna
Avoid using towers higher than 9 metres (30 feet) above the ground
B-006-11-10:
The spacing between the elements on a three-element Yagi antenna, representing the best overall choice, is _____ of a wavelength.
0.2
0.15
0.5
0.75
B-006-11-11:
If the forward gain of a six-element Yagi is about 10 dB, what would the gain of two of these antennas be if they were "stacked"?
13 dB
7 dB
20 dB
10 dB
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