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E-Band and Super Dual band Installation
Guidelines for pole and tower selection
Fabrizio Danti
Milan MW Competence Center Service Team
Introduction
Wind effect on antenna and structures
Sun heating effect on Monopoles
Guidelines on E-Band and SDB antenna installation
2
E-Band and SDB antenna gain and beam width
Antenna gain at 80 GHz frequency is very high and as a
consequence the beam width tends to be very narrow.
Typical specs of parabolic antenna at midrange frequency are:
30 cm.: ≈ 43 dB of gain and 0.9⁰ 3dB beam width
60 cm.: ≈ 50 dB of gain and 0.5⁰ 3dB beam width
Same concepts applies to SDB dual band antennas for the 80
GHz band:
60 cm.: ≈ 50 dB of gain and 0.4⁰ 3dB beam width
To make a comparison, a 60 cm. 38 GHz antenna has 0.9⁰ beam width and a gain of 45 dB.
So the beam width is as narrow as the 30 cm. E-Band antenna.
3
E-Band and SDB antenna radiation pattern envelope (RPE)
RPE represents the maximum gain guaranteed for the antenna and must be lower than ETSI masks
The angle for a 3dB beam loss is 0.45°for 30 cm. and 0.25°for 60 cm. antennas
Directivity is very high, so
antenna gain is going
down sharply when the
antenna is misaligned
from the main beam.
30 cm.
60 cm.
4
E-Band and SDB antenna real radiation pattern
Real radiation patterns of the antennas have narrow
and deep depressions between the main lobe and
the first side lobes.
The attenuation value in these points is variable
from sample to sample and typically ranges
between 20 and 30 dB from the main lobe center.
In E-Band, the angle where the minimum level is
positioned can be around 0.5÷0.7 degrees for a 60
cm. antenna and 1.3÷1.5 degrees for a 30 cm.
antenna.
5
Antenna stability ETSI Requirements
ETSI 302217-4-1: For installation on trellis or towers, this results in a maximum angular deviation of the antenna
main beam axis not higher than 0,3 times the -3 dB beam width under the conditions specified in below table .
Antenna
type
Normal duty
Wind velocity
m/s (km/h)
30 (110)
Ice load
(density 7 kN/m3)
25 mm radial ice
Heavy duty
45 (164)
25 mm radial ice
Above requirements applied to 80Ghz e-band antennas gives the following results:
Antenna
type
30 cm. 80Ghz
3dB
Beam
0.9⁰
0,3 times -3 dB
beam*
0.3⁰
-3 dB Angle
60 cm. 80Ghz
0.5⁰
0.15⁰
0.25⁰
0.5⁰
*correspond to max antenna deviation respect to the pole/tower and not
include pole/towere twist/sway effect
So, the antenna and
corresponding mounting kit are
designed to maintain a limited
deviation even in harsh
conditions (max. deviation is
less than 3dB loss angle).
6
Effect of tower sway on radiation pattern
Normal
Operation
Tower sway
As said before, antenna is designed
to limit the de-focusing even in harsh
conditions, but it is also necessary to
verify if the structure (pole, tower, ..)
where the antenna is installed is
capable to maintain a limited angle
deviation in all conditions to avoid
performances degradation of the link.
In next chapters, these conditions will
be analyzed to define the structure
requirements for the E-Band and SDB
installation.
7
Introduction
Wind effect on antenna and structures
Sun heating effect on Monopoles
Guidelines on E-Band and SDB antenna installation
8
Calculation of wind effect on structures
Calculation of wind effects on the design of steel structures (towers, masts) are regulated in
the European Union by two main standards: EN 1991 and EN 1993.
Similar standards exists also outside the EU.
The standards state that the fixed variable actions (like wind) should be characteristic
values with a probability of exceeding of p=0,02 per year, which corresponds to a return
period of 50 Years.
So, towers/mast deflections and rotations are calculated on the basis of a wind velocity that
derives from the basic wind velocity defined as:
9
Pole/Tower deflection specifications
As an example, if the tower is designed to
have a maximum sway deflection of 1 degree,
this deviation is calculated with an occurrence
probability of 1 time every 50 years (0.02) with a
mean value of the wind in a period of 10
minutes.
The calculation is based on a specific country
zone reference wind speed Vref that is derived
from the meteorological data of the region.
For the same structure, the probability of a 0.5
degrees deflection becomes 68 times higher
(once every 268 days).
10
Pole/Tower deflection impact on E-Band link
As defined in slide n.5, the max attenuation level can be found around
0.5÷0.7 degrees for 60 cm. antenna and 1.3÷1.5 degrees for 30 cm.
antenna.
So, when the intensity of the wind causes a structure deflection close to
that angles, we can have an attenuation that is 20÷30 dB on the link.
The curve of the radiation pattern is very sharp, so the attenuation will
have a lot of variability like this one:
attenuatio
n
time
Fade Margin of E-Band link is usually >>30 dB, so the effect of wind will typically result in a downshift of the modulation. So the availability of higher modulation can be reduced, but the lower
modulations should not be affected.
In case of Super Dual Band, the effect will be even more mitigated by the traffic carried on the lower
band that will not be affected at all by the tower sway.
11
Pole/Tower recommendation against wind effect on E-Band
Structure Deflection
(degrees)
0.5
Recommendation for E-Band antenna Installation
Max deflection is 0.5 degrees (probability once every 50 years)
There is no risk for installation of 30 and 60 cm. antennas.
1
Max deflection is 1 degree (probability once every 50 years), but deflection of
0.5 degrees may occur for 10 minutes almost once in a year.
- 30 cm. Antenna: link is not affected
- 60 cm. Antenna: Availability of higher modulations can be reduced by an
average of 5 min/year, Lower modulations should not be affected
>1
In this case, antenna stability must be carefully verified to avoid link
degradation, in particular if 60 cm. antenna are used.
Impact
No Impact
Very limited, the
degradation introduced at
highest moduation is only a
small percentage of the rain
unavailability
Impact to be carefully
analyzed
The structure sway is bigger in the higher position of the pole/tower.
It is always better to install the E-Band antenna at the lowest available position on
the tower that can guarantee the LOS for the link!!
12
Introduction
Wind effect on antenna and structures
Sun heating effect on Monopoles
Guidelines on E-Band and SDB antenna installation
13
Sun heating deflection effects on Monopoles
E-Band antenna
Height:30 m.
We have experienced some cases of «abnormal» behavior of
links installed in high positions on Monopole structures.
In these links, received level in strongly attenuated for several
hours during sunny days.
Rx level variations along the hours have same pattern every
sunny day:
14
Deflection measured in field to verify root cause of the problem
E-Band antenna
Heigth:30 m.
∠t = ∠a * (L/h) * coefficient
Here: ∠t = tangent angle of tower on top (antenna)
∠ß = straight deflection angle of tower
∠a = deflection angle from measure point
coefficient = tower thermal bending correction factor
Remark:
all the above angles are tiny angles, so it can be calculated
by linear geometry approximately.
Pole deflection is caused by the temperature difference between the sunny and the
shadowy side of the pole.
15
Deflection increased as temperature difference is going up.
E-Band antenna
Heigth:30
Digital
Tiltm.
20
meter
10
1,2
1
0
7:30:00
8:45:00
9:30:00
1:34:00
-10
0,8
-20
RSL
-30
Temp Diff
0,6
Tilt deviation
-40
Measured
time
Antenna tilt Tilt deviation
(°)
(°)
RSL
(dBm)
Temp. Diff.(°C)
sun<-->shadow
-50
0,4
7:30:00 AM
87.65
0.2
-45.0
4
-60
8:45:00 AM
88.45
1.0
-77.7
9.9
-70
9:30:00 AM
87.75
0.3
-63.0
8.3
-80
1:34:00 PM
87.45
0.0
-34.9
0.1
-90
0,2
0
16
Worst case (like in this example) is when link direction is East-West
30m
29.5m
0.9° down tilt
0.6m: 2x 21.4dB = 43dB loss
0.3m: 2x 11.6dB = 23dB loss
0.9° up tilt 30m
0.6m
24m
Mis-aligned
due to sun deflection
(tower thermal bending)
29.5m
0.6m
24m
18m
18m
17.5m
12m
17.5m
In this link, the sun irradiation comes parallel to the link and
therefore both monopoles where affected at the same time,
doubling the attenuation effect.
At lower height, attenuation is much less because the deflection
angle will be limited.
12m
6m
6m
0m
0m
17
Attenuation found in different scenario
Worst Case Attenuation for 60 cm. Antenna
antenna Scenario Scenario Scenario
tower type
height
A
B
C
30
22
10
2
25
15
8
1
Monopole
20
13
6
1
30 m
15
8
4
0
10
5
2
0
Several tests and calculations were done
in links where the exposure to sun was
different (see pictures for the 3
scenarios).
Even in the worst condition (scenario A)
the attenuation introduced by the sun is
limited if the antenna is installed below
15÷20m. of height.
18
Introduction
Wind effect on antenna and structures
Sun heating effect on Monopoles
Guidelines on E-Band and SDB antenna installation
19
Installation Guidelines for Monopoles
Recommended positions for E-Band antennas on Monopoles
 30 cm. antenna at max 20÷25m. height
 60 cm. antenna at max 15÷20m. height
Verify on tower design that sway caused by wind is not more than
1 degree for the antenna installation position.
Always select lower available position (considering LOS)!!
20
Installation Guidelines for Lattice Towers
Recommended positions for E-Band antennas on Lattice Towers
 30 cm. antenna at max 70%. height
 60 cm. antenna at max 50% height
Keep antenna closer to the main structure
Verify on tower design that sway caused by wind is not more than
1 degree for the antenna installation position.
Always select lower available position (considering LOS)!!
21
Installation Guidelines for Rooftop Trellis
OK for E-Band antenna installation (height is usually below 15m.)
In case the structure is higher than 15 m., verify on tower design
that sway caused by wind is not more than 1 degree for the
antenna installation position.
22
Installation Guidelines for Rooftop Poles
OK for E-Band antenna installation (height is usually
below 6m.).
Rooftop pole must have strong side support to reduce
wind shaking.
As a preference, install only one E-Band antenna on the
pole.
In case two E-Band radios have to be installed on the pole
(as in the picture), verify on structure design that sway
caused by wind is not more than 1 degree for the antenna
installation position.
23
Installation Guidelines for Concrete Towers/Wall Mounting
In this case, the structure allows only very limited
deviation, so no particular recommendation for E-Band
antenna installation is needed.
24
Installation Guidelines for Guyed Masts
In this case, the structure typically doesn’t guarantee a good
stability in case of wind and therefore it is not suited for the
installation of E-Band.
It is not recommended to install E-Band antennas on
these masts, unless proper calculations are done to verify
that the twist and sway is limited below 1 degree.
25
E-Band Installation Guidelines from customers
Vodafone GNED (global engineering team) issued a recommendation that is in line with what is
reported in previous slides:
TO2 Germany requires that the maximum tower/pole deflection is:
•
1 degree for existing structures
•
0.5 degree for new structures
26
Thank You.
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