HF Broadband Vertical Antenna FAA 5522 - Mobat-USA

HF Broadband Vertical Antenna FAA 5522 - Mobat-USA
HF Broadband Vertical Antenna
FAA 5522
Frequency Independent Radiator
The FAA 5522 is a high efficiency broadband vertical radiator intended for use
with frequency agile transmission systems covering the 2 - 30 MHz HF band.
Highlights
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Minimal Maintenance requirements
High Reliability
Broadband
No tuning devices, no radials required
Typical SWR 1:1.5 on entire bandwidth
50 ohm coax feed line
RF power 1 kilowatt average
Rugged fiberglass element and steel mounting
components for harsh environments
Mechanical Features
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Length
Weight
Sections
Bottom diameter
Antenna structure
Finishing
Color
Irradiation element material
Ferrule material
Working temperature
Max wind resistance
10 meters
20 Kg
2
52 mm
epoxy fiberglass
Polyurethane paint
gray RAL 7001
high Q Teflon coaxial line
inox steel per AISI 304
-35 °C to +80 °C
180 Km/h
Fig. 1 Antenna Assembly
Electrical Features
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Frequency
Impedance
Polarization
Horizontal radiation pattern
Vertical radiation pattern
Connection to TX
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Ground
2 to 30 MHz
50 ohm
Vertical
360 °
See diagrams
50 Ohms coax cable
(recommend RG-213/U)
Yes
Detailed Description
The FAA 5522 is a broadband HF tactical whip antenna intended for use with
ALE capable equipment for HF communication or ECM systems. Although no
external tuning is necessary for operation over the 2 to 30 MHz band, a line
flattener can be employed to improve performance.
Working Principle
A vertical radiator can be matched to a 50-ohm feed line by either an inductive
(L), a capacitive (C), or an L/C system. An HF-line with its end either open or
shorted can be an "L", a "C", or an "L/C" matching system, depending on the
ratio of its length to a given wavelength. Therefore, most matching systems can
be replaced by a "coax stub."
A very long coax stub, several wavelengths long, can be used as a "multi bandtuning-system" in the 3-30 MHz range. This long line generally offers a correct L
or C or L/C match for each frequency, and consequently, a good match of the
vertical radiator to the feed line.
If a low SWR over the entire frequency range is desired, a folded monopole is the
best solution. This arrangement needs two matching transformers within the
feeder and the tuning line. The FAA 5522 radiator is a configuration of a coaxialfolded monopole. This means low wind load and few problems with snow and
ice. The necessary coaxial cable PTFE (Teflon) is inside the fiberglass radiator
tube. The electrical length of the FAA 5522 is approximately equal to radiator
length.
Physical design
The base of the 10-meter self-supporting radiator is mounted on two sturdy
aluminum plates and insulated by two UV-resistant insulators.
The transmission line, the impedance adaptor (Fig. 9) and the broadband
transformers (Fig. 10) are mounted in a box on the base. The transmission line is
part of the antenna and is delivered on a spool.
Installation guidelines
The ideal mounting for the FAA5522 is 6-10ft (2-3m) above ground, as far away
as possible from reflecting metal objects. A flat roof on a concrete building is also
good. This guarantees low radiation angles. Mounting too close to a structure
(1/2 wavelength or less) or directly on the roof is less recommended. This results
in an inferior radiation pattern and, more importantly, a heavily increased noise
level from installed RF emitters.
Mounting on a tower higher than ¼ wavelength results in high radiation pattern
(up to 60 degrees). The FAA 5522 is a very effective antenna. As with all good
antennas, it reacts to nearby objects such as other antennas, lightning protection
systems, etc. This is particularly pronounced with items that are closer than one
wavelength and longer than 1/2 wavelength. Under these circumstances, the
antenna can receive its own signal back, resulting in increased SWR.
The FAA 5522 is grounded through the transmission line and at the feed line in
the housing. This reduces static noise. The base station needs to be well
grounded. Normally this self-supporting antenna has the same base-mounting
pattern as the currently used AS-3772B/U tunable HF shipboard antenna.
The diagram below represents a real SWR performance relative to a standard
installation on a building roof; the average return loss value is more than 15 dB or
1:1,4 in terms of VSWR.
Fig. 2: Typical SWR performance
Reference level = 0 dB
Fig. 3: Typical SWR Performance
Measure level = 20 dB return loss average
Radiation Patterns
The typical vertical radiation patterns on several frequencies of the HF spectrum
is provided in Fig. 5 to 8. The antenna installation in this case is on a building
roof.
Fig. 4: Pattern radiation F=3 MHz
Fig. 5: Pattern radiation F=7 MHz
Fig. 6: Pattern radiation F=14 MHz
Fig. 7: Pattern radiation F=20 MHz
Fig. 8: Pattern radiation F=26 MHz
Fig. 9: Inside view of antenna box:
Impedance adaptor and Transmission line
Fig. 10: Inside view of impedance adaptor:
Broadband Transformers
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