ETSI TR 103 233 V1.1.1 (2016-04)

TECHNICAL REPORT
Satellite Earth Stations and Systems (SES);
Technical Report on antenna performance
characterization for GSO mobile applications

2 ETSI TR 103 233 V1.1.1 (2016-04)

Reference
DTR/SES-00361
Keywords
antenna, GSO, mobile, performance, satellite
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the
print of the Portable Document Format (PDF) version kept on a specific network drive within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2016.
All rights reserved.
TM TM TM
DECT , PLUGTESTS , UMTS and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members.
TM
3GPP and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI
3 ETSI TR 103 233 V1.1.1 (2016-04)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
1 Scope . 5
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Abbreviations . 7
4 General concepts . 8
5 Antenna Technologies for Mobile Platforms . 9
5.1 Mechanically Steered, Fixed Aperture . 9
5.1.1 Define the antenna . 9
5.1.2 Define the motivation of the special shape/characteristic . 10
5.1.3 Describe the specific non conformant issues . 10
5.2 Hybrid Steering, Variable Aperture. 16
5.2.1 Define the antenna . 16
5.2.2 Define the motivation of the special shape/characteristic . 17
5.2.3 Describe the specific non conformant issue . 18
5.3 Electrically Steered, Variable Aperture . 22
5.3.1 Define the antenna . 22
5.3.2 Define the motivation of the special shape/characteristic . 23
5.3.3 Describe the specific non conformant issues . 23
5.4 Conclusion . 30
6 Analysis Methods & Procedures . 30
6.1 Definition of the "non-conformance-areas" (NCA) method . 30
6.1.1 The NCA method for "free space" radiating pattern . 30
6.1.2 The NCA method for "in-situ" measurement . 34
6.1.2.1 Motion of the platform . 34
6.1.2.2 Installation of the antenna on the platform . 35
6.2 Implementing the NCA method . 36
6.2.1 The NCA method for MS-FA antenna . 36
6.2.2 The NCA method for HS-VA antenna . 37
6.2.3 The NCA method for ES-VA antenna . 39
6.2.4 Conclusion about the NCA method . 41
7 Sharing with Other Systems . 41
7.1 Current Regulatory Environment . 41
7.2 Pragmatic Sharing Approach . 43
7.2.1 General . 43
7.2.2 Terrestrial Systems . 45
7.2.3 Adjacent GSO Networks . 47
7.2.4 NGSO Systems . 49
7.2.4.1 MEO case . 49
7.2.4.2 LEO case . 54
8 Conclusions . 57
Annex A: Bibliography . 58
History . 59

ETSI
4 ETSI TR 103 233 V1.1.1 (2016-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Satellite Earth Stations and Systems
(SES).
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

ETSI
5 ETSI TR 103 233 V1.1.1 (2016-04)
1 Scope
The present document provides a characterization of antenna performances for earth stations on mobile platforms. It
identifies the technologies and antenna types used in such systems, which may not have the same performance
characteristics considered when developing the existing ETSI standards for VSATs.
Antennas used on mobile platforms are typically smaller and have radiation patterns that may have variable symmetry
and/or variable geographic skew angles toward the satellite. These types of antennas are typically used in low profile
antennas or other special applications. Their radiating patterns may show non-conformances with regard to the ETSI
off-axis EIRP density mask.
The present document proposes a method to cope with this non-conformances issue, called the "non-conformance-area"
(NCA) method. The method relies on a geometrical mathematical object, called a NCA, defined as follows:
• A "non-conformance-area" (NCA) is an area of preferably simple geometric shape defined on the antenna
radiating pattern that identifies the set of directions where the ETSI mask is exceeded, associated with an
indicative level of severity in the perspective of a further interference analysis.
As far as 3D geometry in space is concerned, the NCA method is an extension of the ETSI TR 102 375 [i.6] report that
"provides guidelines for determining the parts of the satellite earth station antenna radiation patterns concerned by the
geostationary satellite orbit protection".
The rationale underlying the NCA method is:
1) As long as there is no victim system in the directions of a NCA, there is no possible harmful interference
occurrence for that directions.
2) When a victim system happens to be in the directions of a NCA, a possible interference event occurs in the
scope of a non-conformance to the ETSI mask. This event is called a "hit".
3) A coarse level of severity is associated by analysis to each "hit".
4) Statistics are performed about the occurences of "hits" during operations, providing with a comprehensive
assessment of the hit occurences issue.
The NCA method may support a rationale as suggested by FCC 47 CFR 25.138 (b) [i.1] as stated hereafter:
• "(b) Each applicant for earth station license(s) that proposes levels in excess of those defined in paragraph (a)
of this section shall submit link budget analyses of the operations proposed along with a detailed written
explanation of how each uplink and each transmitted satellite carrier density figure is derived. Applicants
shall also submit a narrative summary which must indicate whether there are margin shortfalls in any of the
current baseline services as a result of the addition of the applicant's higher power service, and if so, how the
applicant intends to resolve those margin short falls. Applicants shall certify that all potentially affected
parties (i.e. those GSO FSS satellite networks that are 2, 4, and 6° apart) acknowledge and do not object to the
use of the applicant's higher power densities."
The NCA method may also support a rationale as suggested by FCC 47 CFR 25.227 (b)(2) [i.2].
ETSI
6 ETSI TR 103 233 V1.1.1 (2016-04)
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
Ka band
[i.1] FCC 47 CFR 25.138: "Blanket Licensing provision of GSO FSS Earth Station in the
19.3-18.8 GHz (space-to-Earth), 19.7-20.2 GHz (space-to-Earth), 28.35-28.6 (Earth-to-Space)
28.35-28.6 GHz (Earth-to-Space), and 29.25-30.0 GHz (Earth-to-Space) bands".
Ku band
[i.2] FCC ESAAS 47 CFR 25.227: "Blanket licensing provisions for Earth Stations Aboard Aircraft
(ESAAs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to-Earth), and
11.7-12.2 GHz (space-to-Earth) frequency bands and transmitting in the 14.0-14.5 GHz
(Earth-to-space) frequency band, operating with Geostationary Satellites in the Fixed-Satellite
Service".
ITU
[i.3] Recommendation ITU-R S.524-9: "Maximum persissible levels of off-axis e.i.r.p density from
earth station in geostationary-satellite orbit networks operating in the fixed-satellite service
transmitting in the 6 Hz, 13 GHz, 14 GHz, and 30 GHz frequency bands".
[i.4] ITU Radio Regulations.
NOTE: Available at https://www.itu.int/pub/R-REG-RR.
ARINC
[i.5] ARINC 791 Mark 1 Aviation Ku-band and Ka-band satellite communication system Part 1 and
Part 2.
ETSI
[i.6] ETSI TR 102 375: "Satellite Earth Stations and Systems (SES); Guidelines for determining the
parts of satellite earth station antenna radiation patterns concerned by the geostationary satellite
orbit protection".
ETSI
7 ETSI TR 103 233 V1.1.1 (2016-04)
[i.7] ETSI EN 302 186: "Satellite Earth Stations and Systems (SES); Harmonised Standard for satellite
mobile Aircraft Earth Stations (AESs) operating in the 11/12/14 GHz frequency bands covering
the essential requirements of article 3.2 of the Directive 2014/53/EU".
[i.8] ETSI EN 303 978: "Satellite Earth Stations and Systems (SES); Harmonised Standard for Earth
Stations on Mobile Platforms (ESOMP) transmitting towards satellites in geostationary orbit,
operating in the 27,5 GHz to 30,0 GHz frequency bands covering the essential requirements of
article 3.2 of the Directive 2014/53/EU".
ECC Report
[i.9] ECC Report 184: "The Use of Earth Stations on Mobile Platforms Operating with GSO Satellite
Networks in the Frequency Ranges 17.3-20.2 GHz and 27.5-30.0 GHz".
NOTE: Available at http://www.erodocdb.dk/docs/doc98/official/pdf/ECCRep184.pdf.
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
1D 1 Direction (phased array) or 1 Dimension (graph)
2D 2 Directions (phased array) or 2 Dimensions (graph)
3D 3 Dimensions (graph)
AES Aircraft Earth Station
ARINC Aeronautical Radio INCorporated.
CFR Code of Federal Regulations
ECC Electronic Communications Committee
EIPR Effective Isotropic Radiated Power
EIRP Equivalent Isotropically Radiated Power
EN European Standard
ESAAS Earth Stations Aboard Aircraft
Escan Electric scan
ESOMP Earth Stations on Mobile Platforms
ESV Earth Stations on Vessels
ES-VA Electric Steered Variable Aperture
ETSI European Telecommunications Standards Institut
FCC Federal Communications Commissions
FSS Fixed-Satellite Service
GSO Geostationnary Satellite Orbit
HS-VA Hybrid Steered Variable Aperture
IMU Inertial Measurment Unit
IPR Intellectual Property Right
ITU International Telecommuncation Union
ITU-R International Telecommunications Union - Radiocommunications sector
LEO Low Earth Orbit
LMES Land Mobile satellite Earth Stations
LOS Line Of Sight
MEO Medium-Earth Orbit
MS-FA Mechanically Steered Fixed Aperture
MS-VA Mechanically Steered Variable Aperture
NCA Non Conformance Area (method)
NGSO Non-Geostationnary Satellite Orbit
PFD Power Flux Density
RMS Root Mean Square
VMES Vehicle-Mounted Earth Stations
ETSI
8 ETSI TR 103 233 V1.1.1 (2016-04)
4 General concepts
Fore the purpose of the present document, the satcom antenna technologies for Mobile Platforms are partitioned as
follows:
1) The radiating panel generates a fixed beam, typically in the boresigth direction of its radiating surface. It is
mechanically aimed toward the satellite. For the purpose of the present document, this antenna type is called
MS-FA for Mechanically Steered - Fixed Aperture.
2) The radiating panel has an electric beam steering capacity either 1D or 2D (for 1 and 2 Directions) from its
boresight. In case of a partial electric beam steering (a complementary mechanical beam steering is
implemented), the antenna type is called HS-VA for Hybrid Steered - Variable Aperture.
3) The radiating panel has an electric beam steering capacity either 1D or 2D (for 1 and 2 Directions). In case of
full electric beam steering (no complementary mechanical beam steering is required), the antenna is called
ES-VA for Electric Steered -Variable Aperture.
For ease of understanding, each antenna type is matched to a particular antenna technology:
1) Mechanically Steered Fixed Aperture (MS-FA): a rectangular radiating panel mounted on a mechanical
Elevation over Azimuth positioner. The antenna is housed under a "low profile" radome mounted flat on the
platform body (for instance the fuselage of an aircraft).
2) Hybrid Steered Variable Aperture (HS-VA): a MS-FA antenna where the antenna radiating panel performs an
electric cross-elevation axis. The overall physical shape is kept unchanged with regard to MS-FA type. The
antenna is housed the under a "low profile" radome the same way.
3) Electric Steered Variable Aperture: a thin radiating panel mounted flat on the platform's body (for instance the
aircraft fuselage), and performing a 2D electric beam-steering from its boresight. It is sometimes referred to as
a conformal antenna.
The rationale linking the antenna types to the antenna technologies is:
1) Only asymmetrical (e.g. "low profile") antennas are considered in the scope of this study. Hence, the
cross-elevation axis, if any, is bound to be electric. A mechanical cross-elevation axis rotation has its range
limited by the radiating panel bumping into the radome and into its floor.
2) If the elevation axis is mechanical, the antenna type is either MS-FA or HS-VA depending on the existence of
one cross-elevation axis or not.
3) If the elevation axis is electric, the antenna type is either MS-FA (if the radiating panel surface is typically
inclined from the platform horizontal around 45°) or ES-VA (if the radiating panel is mounted flat/horizontal
on the platform body).
Several other technologies such as multipanel antennas, 3 axis mechanical antennas, etc., are eligible that can take place
between the classic Elevation over Azimuth (e.g. MS-FA) and the full 2D phased array conformal antenna
(e.g. ES-VA). But the objective of this technical report is not to compare antenna technologies or to discuss about their
feasability. The objective of this technical report is to work out a method (the NCA method) to address
non-conformances with regard to the ETSI off-axis EIRP density mask on a generic basis. The three antenna types
above have been retained to illustrate this method.
One should note that the three antenna types above can also be related to the typical maps shown on Figure 1 (satcom
on-axis EIRP density maps):
1) The MS-FA antenna on-axis EIRP density is restricted by its poor directivity when operated on the equator
(the so called "equator effect" according to the Arinc 791 standard [i.5]). Furthermore, the antenna cannot be
operated at the satellite nadir because of the positioner azimuth gimbal lock (the black spot at the satellite
nadir).
2) The HS-VA antenna on-axis EIRP density is lower at the far East/West to the target GSO satellite nadir
because of the electronic cross-elevation axis scan range being limited.
3) The ES-VA antenna performances decrease when the target GSO satellite elevation is low because of the 2D
phased array limited scan range.
ETSI
9 ETSI TR 103 233 V1.1.1 (2016-04)
MS-FA HS-VA ES-VA
NOTE: The Earth as viewed by a GSO satellite. The target satellite nadir is at the center . The colored
black/red/white mask provides an indication of the terminal maximum allowable on-axis EIRP density (The
clearer the higher the EIRP density).

Figure 1: EIRP density maps depending on the Earth terminal location
The key point is the EIRP density to be reduced in given situations, down to switching off the transmission, to prevent
harmful interferences to adjacent systems.
The objective of the following chapter is to provide further analysis and clarification about this issue. The analysis will
be threefold for each antenna type:
1) Define the antenna.
2) Describe the motivation for the special shape/characteristics.
3) Describe the specific non conformant issues with regard to spatially symmetric antenna (as the circular
parabolic reflector) related ETSI standards.
5 Antenna Technologies for Mobile Platforms
5.1 Mechanically Steered, Fixed Aperture
5.1.1 Define the antenna
A MS-FA antenna is shown on Figure 2. The radiating panel (yellow) is typically of rectangular shape and is mounted
on an Elevation over Azimuth mechanical gimbal. The antenna beam follows the radiating panel boresight direction.
• The Z rotational axis is the electromechanical Azimuth axis. Its movement is n × 360° with an unlimited
number of turns.
• The Y rotational axis represents the electromechanical Elevation axis. Its movement ranges typically 0° to 90°
from the horizontal.
• The XY plane follows the radiating panel rectangular surface. In the scope of this study, the radiating panel is
smaller in the X direction (Height) than in the Y direction (Width) because the antenna is low profile.
ETSI
10 ETSI TR 103 233 V1.1.1 (2016-04)
Z
Azimuth
Beam direction
X
Y
Elevation
Figure 2: MS-FA antenna overview
5.1.2 Define the motivation of the special shape/characteristic
The motivation for a MS-FA antenna is its capability to be housed under a low profile radome while being able to target
low elevation satellites. The rectangular shape of the radiating panel maximizes the ratio between the radiating panel
surface and the antenna sweep volume, and thus minimizes the height of the radome.
There are many implementations for the radiating panel : elliptic parabolic, multiparabolic, lenses arrays, waveguides
arrays, patches, horn boxes, etc. The requirements are stringent on the radiating diagram: dual polarization switched or
driven, dual band or wideband, environmental conditions, low cost, etc.
The Elevation over Azimuth gimbal is classic. The key point is the aiming accuracy - down to ±0,2° is required by the
FCC - to be achieved on a mobile platform. The requirements are stringent on motor torques, frictions forces, axis
alignment, axis coders accuracy, IMU, conscan tracking … A well-known weakness is the inability to track a satellite
located in the vicinity of the azimuth axis direction (the so called "azimuth gimbal lock" effect), the gimbal behaving as
a spinning top around its Azimuth axis (https://en.wikipedia.org/wiki/Gimbal lock). The aiming accuracy is impaired
when the antenna is aimed at high elevations satellites.
5.1.3 Describe the specific non conformant issues
A 40 × 10 cm Ka band rectangular radiating panel is considered for the analysis.
The analysis is performed for an average 25 dBW/40 kHz on axis EIRP density at 30 GHz.
Figure 3 provides a simulated radiating pattern (left) and compares it to the ETSI mask (right) (areas in excess in white),
assuming the satcom located on the same longitude as the satellite. Figure 4 provides a 3D view of the radiating pattern.
The horizontal and vertical cuts of the radiating pattern are provided on Figure 5 and Figure 6.
The radiating pattern is cross-shaped. The ETSI mask is strongly exceeded in the up/down direction.
ETSI
11 ETSI TR 103 233 V1.1.1 (2016-04)
60x60°° 60x60°
10x10° 10x10°
±3°
±2°
±2°
Radiating pattern Excess to the ETSI mask

NOTE: The ±3° limits along the vertical axis indicates the GSO arc assuming the satcom is located on the satellite
meridian, with its azimuth axis vertical. The ±2° limits along the horizontal axis indicates the frontier with
the adjacent GSO satellites. The 3 dB relaxation on the ETSI mask is taken into account where applies.
Assumptions: 40 × 10 cm panel, uniform aperture, 25 dBW/40 kHz on axis EIRP, 30 GHz, no radome.

Figure 3: MS-FA radiating pattern 2D view
25 dBW/40 kHz
-50 dBW/40 kHz
Figure 4: MS-FA radiating pattern 3D view
ETSI
12 ETSI TR 103 233 V1.1.1 (2016-04)

NOTE: ETSI mask (in red): no relaxation. ±0,2° margin included for the aiming accuracy. Assumptions: 40 ×
10 cm panel, uniform aperture, 25 dBW/40 kHz on axis EIRP density, 30 GHz, no radome.

Figure 5: MS-FA radiating pattern horizontal cut (e.g. following radiating panel broadside)

NOTE: ETSI mask (in red) with no relaxation. ±0,2° margin taken for the aiming accuracy. Assumptions: 40 ×
10 cm panel, uniform aperture, 25 dBW/40 kHz on axis EIRP density, 30 GHz, no radome.

Figure 6: MS-FA radiating pattern vertical cut (following radiating panel narrow side)
Figure 7 and Figure 8 provide a theoretical radiating pattern of a 12' (30 cm) dish antenna to compare with. The dish
antenna looks cleaner than its rectangular counterpart, reflecting the ETSI mask favouring round shaped symmetric
antennas. But neither antenna rectangular or circular is permitted to operate at a 25 dBW/40 kHz EIRP density
according to the ETSI rules. Moreover the Figure 5 shows that the rectangular aperture complies better to the ETSI
mask as far as the GSO arc is considered.
ETSI
13 ETSI TR 103 233 V1.1.1 (2016-04)
60x60°
60x60°
10x10° 10x10°
±3°
±2°
±2°
Radiating pattern Excess to the ETSI mask

Figure 7: Radiating pattern circular dish 30 cm

Figure 8: Radiating pattern circular dish 12' (30 cm)
A commonplace issue for a MS-FA antenna is the radiating panel showing a rotation around its main beam direction
(while aimed to the satellite), the so called "skew angle" as shown on Figure 9 and Figure 10.
ETSI
14 ETSI TR 103 233 V1.1.1 (2016-04)
Antenna
GSO Arc
Skew
Figure 9: Antenna skew
60x60°°
60x60°
Skew
10x10° 10x10°
GSO arc
±3°
±2° ±2°
Radiating pattern Excess to the ETSI mask

Figure 10: MS-FA radiating pattern and antenna skew
The skew angle depends on the satcom location on the Earth and its platform attitude roll, pitch, yaw. Calculating the
skew angle requires a suite of Euler rotations, from space to Earth, from Earth to the platform, from the platform to the
antenna radiating panel.
There is anyway a simple equation in the case the antenna Azimuth axis is locally vertical and the satellite is a GSO
satellite:
tan (skew) = - cotan (latitude).sin (delta-longitude)
where "delta-longitude" and "latitude" are the satcom longitude and latitude, "delta-longitude" being the longitude
relative to GSO satellite longitude.
Figure 11 provides an illustration of this skew angle that is named later "natural skew". The skew angle is equal to zero
when the satcom is located on the satellite longitude.
ETSI
15 ETSI TR 103 233 V1.1.1 (2016-04)
North
skew
Platform
Equator
Satellite
Nadir
South
Figure 11: Earth as viewed from the satellite- natural skew
Beyond a given value of skew, typically 45°, the main beam of the antenna infringes into the adjacent GSO satellites
vicinity. The on-axis EIRP density is reduced accordingly to meet the ETSI off-axis EIRP mask on the GSO arc.
Targent
satellite2x3°boxo
ne
Adjacent satellite
2x3° box
Figure 12: The radiating pattern
(shown as it excess to the ETSI mask) infringing into the adjacent GSO satellite area
High skew angles explain the east-west restriction on the MS-FA EIRP density map shown on the Figure 13 The so
called "equator effect" according to the Arinc 791 [i.5] standard is quite visible.
The restriction at the satellite nadir (the black spot) reflects the azimuth axe lock effect of the antenna gimbal.
ETSI
16 ETSI TR 103 233 V1.1.1 (2016-04)

NOTE: 3 GSO satellites 120° spaced starting from 63,3°East. The colored black/red/white mask provides an
indication of the terminal permitted EIRP density (The clearer the higher the EIRP density).

Figure 13: MS-FA antenna EIRP density map on the Earth terminal location
The above properties can be taken for granted as a general fact for MS-FA antennas. Real cases are more complex.
Neither the target GSO satellite nor the adjacent GSO satellites are perfectly centred on its 2 × 3° box. A mobile
platform is not purely horizontal. The radiating pattern can suffer from several impairments: grating lobes, spurious
sidelobes, radome transmission and reflections, platform's body masks. The interferences to the NGSO satellites topic
should also be addressed.
In this end, this is a case by case analysis. This is the purpose of the NCA method to address this issue.
5.2 Hybrid Steering, Variable Aperture
5.2.1 Define the antenna
A "1 D Phased Array" radiating panel of rectangular shape (yellow) is mounted on an electromechanical two-axis
gimbal Elevation over Azimuth type (in dark grey):
• The Z rotational axis is the electromechanical Azimuth axis. Its movement is n × 360° with an unlimited
number of turns.
• The Y rotational axis represents the electromechanical Elevation axis. Its movement ranges typically from 0°
to 90° from the horizontal.
• The X rotational axis represents the Cross-Elevation axis which is the electric axis of the 1 D Phased Array
radiating panel. It is located at the centre of the radiating panel and runs parallel to its narrow side. The cross
elevation rotation angle, so called escan angle, ranges typically ±45° from the normal to the radiating panel.
Figure 14 shows the antenna in two values for the Elevation (Y) and Cross-Elevation (X, escan) angles.
ETSI
17 ETSI TR 103 233 V1.1.1 (2016-04)
Z
Z
Beam direction
Beam direction X
X
escan
escan
Y Y
Figure 14: The HS-VA "1D Phased Array" satcom antenna
5.2.2 Define the motivation of the special shape/characteristic
The 1D HS-VA antenna has three advantages:
• It can be housed under a low profile radome while aiming a low elevation direction the same as for the MS-FA
antenna.
• The positionner is 3-axis.
• The high directivity of the radiating panel along its broadside is carried out electrically and is therefore less
sensitive to mechanical stress (backlash, friction, inertia), that favours a precise antenna aiming.
The specific advantages of a 3-axis positioner are:
• No azimuth gimbal axe lock. Operation at the satellite nadir is possible.
• Capability to adjust the "skew" with the cross elevation axis (angle escan). This permits to master the radio
interference to the adjacent satellites, including the NGSO satellite ones.
The skew adjustment capability depends on the local elevation of the satellite. There is a simple formulae when the
Azimuth axis is vertical:
sin(skew) = tan(escan) tan(elevation)
("skew" starting from the "natural skew" at escan = 0° position)
For escan ranging from -45 ° to 45 °, and assuming the azimuth angle is vertical:
• If the satellite shows a more than 45° elevation, all the values of skew are possible.
• For a low elevation satellite, the skew can be adjusted by up to plus or minus the satellite local elevation.
With regard to the MS-FA antenna, the HS-VA antenna is no more impaired by the skew limitation and the gimbal axe
lock as long as the escan angle does not meet its (say ±45°) maximum that occurs the satcom is located at the far
east/west of the satellite nadir, as shown on the Figure 15.
ETSI
18 ETSI TR 103 233 V1.1.1 (2016-04)

NOTE: 3 GSO satellites 120° spaced starting from 63,3° East. The colored black/red/white mask provides an
indication of the terminal permitted EIRP density (The clearer the higher the EIRP density).

Figure 15: HS-VA antenna EIRP density map on the Earth terminal location
5.2.3 Describe the specific non conformant issue
A 40 × 10 cm Ka band rectangular radiating panel is considered for the analysis.
The analysis is performed for an average 25 dBW/40 kHz on axis EIRP density at 30 GHz.
Figure 16 provides a simulated radiating pattern (left) and compares it to the ETSI mask (right, excess areas in white).
The Cross-Elevation escan is set to 0°. The radiating pattern is similar to a MS-VA antenna. This is quite visible on
Figure 17. The horizontal and vertical cuts are provided on Figure 18 and Figure 19.
ETSI
19 ETSI TR 103 233 V1.1.1 (2016-04)
60x60°° 60x60°
10x10°
10x10°
±3°
±2°
±2°
Radiating pattern Excess to the ETSI mask

NOTE: The ±3° limits along the vertical axis indicates the GSO arc area assuming the satcom is located on the
satellite meridian with its azimuth axis vertical. The ±2° limits along the horizontal axis indicates the frontier
to the adjacent GSO satellites. The 3 dB relaxation on the ETSI mask is taken into account where applies.
Assumptions: 40 × 10 cm panel, 25 dBW/40 kHz on axis EIRP, 30 GHz, no radome, escan = 0°.

Figure 16: HS-VA radiating pattern escan = 0° 2D view
25 dBW/40 kHz
-50 dBW/40 kHz
Figure 17: HS-VA radiating pattern escan = 0° 3D view
ETSI
20 ETSI TR 103 233 V1.1.1 (2016-04)

NOTE: ETSI mask (in red): no relaxation and ±0,2° margin taken for the aiming accuracy. A 6 dB Hamming taper
is applied on the aperture law. 3° and 0.5 dB RMS phase/amplitude RMS accuracy for radiating elements.

Figure 18: HS-VA radiating pattern escan = 0° horizontal cut (e.g. following broadside)

NOTE: ETSI mask (in red): no relaxation and ±0,2° margin taken for the aiming accuracy. A 6 dB Hamming taper
is applied on the aperture law. 3° and 0,5 dB RMS phase/amplitude RMS accuracy for radiating elements.

Figure 19: HS-VA radiating pattern escan = 0° vertical cut (e.g. following narrow side)
Figure 20 and Figure 21 show the radiating pattern of the HS-VA antenna for escan = 30° and escan = 45°. The main
beam inflates in the direction of the escan angle. The vertical sidelobes pattern follows an elliptical path. The antenna
gain decreases following a cos (escan) law.
ETSI
21 ETSI TR 103 233 V1.1.1 (2016-04)
60x60°°
60x60°
10x10° 10x10°
±3°
±2°
±2°
1D Phased array
spurious
Radiating pattern Excess to the ETSI mask

Figure 20: HS-VA radiating pattern escan = 30°
60x60°°
60x60°
10x10° 10x10°
±3°
±2° ±2°
1D Phased array
spurious
Radiating pattern Excess to the ETSI mask

Figure 21: HS-VA radiating pattern escan = 45°
A commonplace feature of phased arrays is the upsurge of spurious sidelobes due to the radiating elements
amplitude/phased inaccuracy (typically 0,5 dB and 3° RMS). This point is highlighted on Figure 22.
The radiating pattern can suffer from several other impairments: grating lobes, radome transmission and reflections,
platform's body masks, etc., that are not described here.
ETSI
22 ETSI TR 103 233 V1.1.1 (2016-04)
1D Phased
array spurious
Figure 22: HS-VA radiating pattern escan = 45° horizontal cut (broadside)
5.3 Electrically Steered, Variable Aperture
5.3.1 Define the antenna
An ES-VA antenna is shown on Figure 23. The radiating panel is of rectangular shape (yellow) and is mounted
flat/horizontal on the top of the platform's body. The antenna beam is aimed electrically (2D) toward the target satellite.
• The XY plane is the radiating panel referential. For convenience, the X axis is assumed to be aligned with the
platform heading direction. The Z axis is the panel boresight direction that is vertical to the platform's body.
An Elevation over Azimuth scheme is appropriate to describe the beam steering: Azimuth rotation around the Z axis
and escan axis playing the antenna elevation axis. Where the Azimuth axis mechanical, the ES-VA antenna would
performs like an MS-FA antenna with the elevation axis being electric instead of mechanical. A skew angle is thus
derived a similar way. Since the ES-VA antenna is a full 2D phased type, the radiating panel is fixed on the platform
body, as if the mechanical Azimuth mechanical rotation above is simultaneously compensated by a mechanical
contra-rotation of the same magnitude. There is no physical rotation, but the "Azimuth contra-rotation" effect is anyway
quite visible on the antenna radiating pattern (the cross shaped sidelobes are rotating following the Azimuth contra-
rotation angles). It is a specific feature of the ES-VA antenna with regard to MS-FA antenna.
The variants to the ES-VA antenna are:
1) The radiating panel is a 1D phased array that mechanically turns around the Azimuth axis, the radiating panel
following the escan axis. This is actually a MS-FA antenna with an electric Elevation axis.
2) The radiating panel is of circular shape. There "Azimuth contra-rotation" effect exists but is not visible
becaused of the circular symetry.

ETSI
23 ETSI TR 103 233 V1.1.1 (2016-04)
Beam direction
Z
escan
Azimut
X Y
escan axis
Figure 23: A square shaped ES-VA Antenna overview
5.3.2 Define the motivation of the special shape/characteristic
The ES-VA is a dream design because of its being almost conformal to the platform's body with no moving part.
It suffers radiating pattern performance losses when the escan angle increases beyond 60°.
5.3.3 Describe the specific non conformant issues
A 40 × 40 cm Ka band square shaped radiating panel is considered for the analysis.
The analysis is performed for an average 25 dBW/40 kHz on axis EIRP density at 30 GHz.
Figure 24 provides a simulated radiating pattern (left) and compares it to the ETSI mask (right, excess areas in white).
The azimuth angle and the electric scan angle are set to 0°. The horizontal and vertical cuts are provided on Figure 26.
60x60°° 60x60°
10x10°
10x10°
±3°
±2° ±2°
Radiating pattern Excess to the ETSI mask

NOTE: The ±3° limits along the vertical axis indicates the GSO arc assuming the satcom is located on the satellite
meridian with its azimuth axis vertical.
The ±2° limits along the horizontal axis indicates the frontier wirh the adjacent GSO satellites.
The 3 dB relaxation on the ETSI mask is taken into account where applies.
Assumptions: 40 × 40 cm panel, 25 dBW/40 kHz on axis EIRP, 30 GHz, no radome.

Figure 24: Square shaped ES-VA radiating pattern escan = azimuth = 0° 2D view
ETSI
24 ETSI TR 103 233 V1.1.1 (2016-04)
25 dBW/40 kHz
-50 dBW/40 kHz
Figure 25: Square shaped ES-VA radiating pattern escan = azimuth = 0° 3D view

NOTE: ETSI mask (in red): no relaxation and ±0,2° margin taken for the aiming accuracy.

Figure 26: Square shaped ES-VA Radiating pattern escan = 0° horizontal cut
(e.g. following radiating panel broadside)
The operational area is restricted to locations where the satellite shows a sufficient elevation angle as shown on
Figure 27.
ETSI
25 ETSI TR 103 233 V1.1.1 (2016-04)

NOTE: 3 GSO satellites 120° spaced starting from 63,3° East. The colored black/red/white mask provides an
indication of the terminal permitted EIRP density (The clearer the higher the EIRP density).

Figure 27: ES-VA antenna EIRP density map on the Earth terminal location
Figure 28 shows that the radiating pattern fairly complies with the ETSI mask as long as the escan angle is less than
60°.
ETSI
26 ETSI TR 103 233 V1.1.1 (2016-04)
60x60°° 60x60° Escan = 30°
Radiating pattern Excess to the ETSI mask

60x60°° 60x60°
Escan=45°
Radiating pattern Excess to the ETSI mask

60x60°° 60x60° Escan=60°
Radiating pattern Excess to the ETSI mask

Figure 28: Square shaped ES-VA radiating patterns azimuth = 0°
ETSI
27 ETSI TR 103 233 V1.1.1 (2016-04)
Figure 29 highlights the cross shaped sidelobes being sensitive to the the related "Azimuth contra-rotation" effect.
60x60°° 60x60° Escan = 30°
Azimuth contra rotation
effect
Radiating pattern Excess to the ETSI mask

60x60°° 60x60°
Escan=45°
Radiating p
...