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Antennas for amateur 70 cm repeaters
430-440 MHz
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If you are installing the repeater on the high mountain at the tough
weather conditions or on the top of the broadcasting radio station mast
than it is better not to apply the conventional antennas covered by the
glass-fiber cases. They may be fast broken under the influence of the ice
and wind. In these conditions we recommend to use highly reliable antennas
based upon the loop aluminum dipoles - D4 UHF
(70 cm). They are made of the thick tube with the application of Argon
welding. They possess a polymeric coating, are fully grounded by the
direct current and do not need to be tuned.
Antenna D4 UHF represents folded Pistolcors dipoles. Its
primaries: wide operating band and nearly circular pattern. Welded
construction of dipole eliminates possibility of intermodulation. Emitting
unit directional pattern can be slightly corrected by changing distance
from it to mast. Collapsible construction provides easy antenna mounting
and dismounting
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| Antenna D4 UHF |
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Electrical specifications
| Model |
D4 UHF
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Operating frequency band, MHz |
400-490 |
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VSWR, not more than |
1.5 |
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Gain OMNI, dBd |
6 |
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OFFSET, dBd |
9 |
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Sector in vertical plane ,
-3dB |
18° |
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Impedance, Ohm |
50 |
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Max. power input, W |
400 | |
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Mechanical specifications
| Model |
D4 UHF |
| Mass, kg |
7,3 |
| Height/Length, M |
1,7 |
| Construction material |
Aluminium alloy
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| Mast diametr, mm |
38-65 |
| Rated wind velocity, m/s |
45 |
| Wind loading area, m2 |
0,112 |
| Load of side wind 45 m/s, H |
128 |
| Rated wind velocity with 0.5" icing,
m/s |
28 |
| Temperature range, °C |
from -50 to +50
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| Connector |
N-female
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D4 UHF in H-plane, OMNI (1/2λ
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D4 UHF in H-plane, OFFSET (1/4λ
)
D4 UHF in H-plane, OFFSET (1/8λ
)
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