B-006-12: Wire antennas - types, dimensions, characteristics
B-006-12-01:
If you made a half-wavelength dipole antenna for 28.550 MHz, how long would it be?
5.08 metres (16.62 ft)
10.5 metres (34.37 ft)
28.55 metres (93.45 ft)
10.16 metres (33.26 ft)
B-006-12-02:
What is one disadvantage of a random wire antenna?
You may experience RF feedback in your station
It usually produces vertically polarized radiation
It must be longer than 1 wavelength
You must use an inverted T matching network for multi-band operation
B-006-12-03:
What is the low angle radiation pattern of an ideal half-wavelength dipole HF antenna installed parallel to the earth?
It is a figure-eight, perpendicular to the antenna
It is a circle (equal radiation in all directions)
It is two smaller lobes on one side of the antenna, and one larger lobe on the other side
It is a figure-eight, off both ends of the antenna
B-006-12-04:
The impedances in ohms at the feed point of the dipole and folded dipole are, respectively:
73 and 300
73 and 150
52 and 100
52 and 200
B-006-12-05:
A dipole transmitting antenna, placed so that the ends are pointing North/South, radiates:
mostly to the East and West
mostly to the South and North
mostly to the South
equally in all directions
B-006-12-06:
How does the bandwidth of a folded dipole antenna compare with that of a simple dipole antenna?
It is greater
It is essentially the same
It is less than 50%
It is 0.707 times the bandwidth
B-006-12-07:
What is a disadvantage of using an antenna equipped with traps?
It will radiate harmonics
It is too sharply directional at lower frequencies
It must be neutralized
It can only be used for one band
B-006-12-08:
What is an advantage of using a trap antenna?
It may be used for multi-band operation
It has high directivity at the higher frequencies
It has high gain
It minimizes harmonic radiation
B-006-12-09:
The "doublet antenna" is the most common in the amateur service. If you were to cut this antenna for 3.75 MHz, what would be its approximate length?
38 meters (125 ft.)
32 meters (105 ft.)
45 meters (145 ft.)
75 meters (245 ft.)
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