ETSI TR 104 098 V1.1.1 (2025-05)

TECHNICAL REPORT
Technical mitigation measures to protect RAS against
interference from ground based vehicular radars within
77 - 81 GHz to support revision of ECC/DEC/(04)03

2 ETSI TR 104 098 V1.1.1 (2025-05)

Reference
DTR/ERM-TGSRR-582
Keywords
automotive, interference analysis, radar
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ETSI
3 ETSI TR 104 098 V1.1.1 (2025-05)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Regulatory frameworks and other background information. 9
4.1 Spectrum allocations in the range 77 - 81 GHz in CEPT . 9
4.1.1 European Common allocations table . 9
4.1.2 Relevant footnotes . 9
4.1.2.1 Introduction . 9
4.1.2.2 Footnote 5.149 . 10
4.1.2.3 Footnote 5.559B . 10
4.1.2.4 Footnote 5.560 . 10
4.2 Regulatory framework for ground based vehicular radar operating in 77 - 81 GHz in CEPT . 10
4.3 Regulatory framework for RAS in CEPT . 10
4.4 Existing radio quiet zones around RAS sites based on national regulation . 11
4.5 RAS operation details . 11
5 Earlier studies that deal with interference of radar operating in 76 - 81GHz or parts thereof into
the radio astronomy service . 12
5.1 Introduction . 12
5.2 Studies in ECC Report 056 . 12
5.3 Studies in ECC Report 222 . 12
5.4 Studies in Report ITU-R M.2322 . 13
5.5 Studies in Report ITU-R RA.2457 . 13
5.6 Summary of the former studies . 14
6 New CEPT study based on information provided in ETSI TR 103 593 . 14
6.1 Introduction . 14
6.2 Summary of the Results from ECC Report 350 regarding interference from vehicular ground based
radars into RAS . 15
6.3 Revision of ECC/DEC/(04)03 . 15
7 Review of the study results from ECC report 350 . 16
7.1 Illustration of the RAS exclusion zones based on the results from ECC Report 350 . 16
7.2 Used RAS antenna pattern. 17
7.3 Traffic density assumptions . 18
7.4 Radar transmit power . 18
7.5 Summary . 18
8 Alternative mitigation measures . 18
8.1 Introduction . 18
8.2 Mitigation in space . 19
8.3 Mitigation in power . 19
8.4 Mitigation in frequency . 20
8.5 Mitigation in time . 20
8.6 Mitigation in code . 21
8.7 Mitigation in propagation . 21
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4 ETSI TR 104 098 V1.1.1 (2025-05)
9 Mitigation measures and related technical information to be used in the addendum to ECC Report
350 . 22
9.1 Background . 22
9.2 Simulation . 22
9.3 Mitigation measures . 22
Annex A: Coordination zones . 24
A.1 Introduction to ECC Report 351 coordination zones . 24
A.2 Coordination zones in the present document . 24
A.3 Differences between ECC Report 351 and ECC Report 350 . 24
A.4 Comparison of exclusion zones in ECC Report 350 and ECC Report 351 . 24
A.5 Coordination zones in ECC report 351 . 26
A.6 Informal assessment of coordination zone effectiveness for all RAS stations . 27
A.7 Assessment of potential effectiveness of coordination zones . 28
A.8 Provisional conclusion . 29
Annex B: Effectiveness of local shielding . 30
B.1 Introduction . 30
B.2 Single barrier case . 30
B.3 Provisional conclusion . 32
B.4 Addendum: Extension with clutter loss . 32
Annex C: Interference compensation . 33
C.1 Introduction . 33
C.2 Provisional conclusion . 33
Annex D: Sidelobe reduction for parabolic antennae . 34
D.1 Introduction . 34
D.2 Literature references . 34
D.2.1 Edge treatment for sidelobe reduction of parabolic reflector antenna with a two-layer absorber . 34
D.2.2 Sidelobe reduction of a parabolic reflector with auxiliary reflectors . 35
D.2.3 Effect of design parameters on sidelobe level of short-focus parabolic reflector antenna . 36
D.3 Provisional conclusion . 36
Annex E: Peak traffic density mismatch . 37
E.1 Introduction . 37
E.2 Traffic Density distribution in ECC Report 350 . 37
E.3 Average car density discrepancy . 37
Annex F: EU Legal baseline for motor vehicles and driver assistance systems also targeting
protection of vulnerable road users . 39
F.1 General safety regulation for new vehicles . 39
F.2 Technical aspects in application of radar to cover legal requirements . 39
Annex G: Bibliography . 40
Annex H: Change history . 41
History . 43
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5 ETSI TR 104 098 V1.1.1 (2025-05)
Intellectual Property Rights
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Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Electromagnetic compatibility and Radio
spectrum Matters (ERM).
Modal verbs terminology
In the present document "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
6 ETSI TR 104 098 V1.1.1 (2025-05)
1 Scope
The present document describes technical interference mitigation measures to protect RAS against interference from
ground based vehicular radars (as potential alternatives to protection zones). The present document is based on the
existing studies in ECC report 350 [i.12] and is focused on the open question (see LS in ERM(24)083040) on
practicality of protection zones raised by the industry during ECC discussions (FM and SRD/MG) on the public
consultation comments for revision of ECC/DEC/(04)03 [i.1].
2 References
2.1 Normative references
Normative references are not applicable in the present document.
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.
[i.1] ECC/DEC/(04)03 (Approved 19 March 2004): "The frequency band 77-81 GHz to be designated
for the use of Automotive Short Range Radars".
[i.2] ECC Report 056 (10/2004): "Compatibility of automotive collision warning Short Range Radar
operating at 79 GHz with radiocommunication services".
[i.3] ERC Report 025 (most recent inforce version): "The European table of frequency allocations and
applications in the frequency range 8.3 kHz to 3000 GHz".
[i.4] Committee on Radio Astronomy Frequencies (CRAF) (web 2024): "List of radio quiet zones
around observatories in Europe".
[i.5] ECC Report 351 (02/2023): "UWB radiodetermination applications within the frequency range
116 GHz to 148.5 GHz for vehicular use".
[i.6] Recommendation ITU-R RA.769-2 (05/2003): "Protection criteria used for radio astronomical
measurements".
[i.7] Recommendation ITU-R RA.1513-2 (03/2015): "Levels of data loss to radio astronomy
observations and percentage-of-time criteria resulting from degradation by interference for
frequency bands allocated to the radio astronomy service on a primary basis".
[i.8] ECC Report 222 (09/2014): "The impact of Surveillance Radar equipment operating in the 76 to
79 GHz range for helicopter application on radio systems".
[i.9] Recommendation ITU-R M.2322-0 (11/2014): "Systems characteristics and compatibility of
automotive radars operating in the frequency band 77.5-78 GHz for sharing studies".
[i.10] Recommendation ITU-R RA.2457-0 (06/2019): "Coexistence between the radio astronomy service
and radiolocation service applications in the frequency band 76-81 GHz".
[i.11] ETSI TR 103 593 (V1.1.1): "System Reference document (SRdoc); Transmission characteristics;
Technical characteristics for radiodetermination equipment for ground based vehicular
applications within the frequency range 77 GHz to 81 GHz".
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7 ETSI TR 104 098 V1.1.1 (2025-05)
[i.12] ECC Report 350 (02/2023): "Radiodetermination equipment for ground based vehicular
applications in 77-81 GHz".
[i.13] SRD/MG #91 - SRDMG(24)030: "PC summary draft revision of ECC Decision (04)03".
[i.14] TC ERM - ERM(24)083040: "LSin from WGFM on ground based vehicular radars mitigation
measures for the protection of RAS".
[i.15] ERMTGSRR - ERMTGSRR(24)050007: "LSin from WGFM on ground based vehicular radars
mitigation measures for the protection of RAS".
[i.16] CEPT WG SE - SE24_WI82: "Ground based vehicular radar mitigations".
[i.17] Committee on Radio Astronomy Frequencies (CRAF) (2005): "CRAF Handbook for Radio
Astronomy".
[i.18] ITU (2013) "Handbook on Radio Astronomy".
[i.19] Recommendation ITU-R RA.314-9 (2002): "Preferred frequency bands for radio astronomical
measurements".
[i.20] Recommendation ITU-R RA.2126-1 (2013): "Techniques for mitigation of radio frequency
interference in radio astronomy".
[i.21] Alessandro Cabras: "Monitoring and Mitigation of RFI in Radio Astronomy Using Artificial
Intelligence", 2. Forum della Ricerca Sperimentale e Tecnologica in INAF 2024.
[i.22] Recommendation ITU-R RA.2259-1 (2021): "Characteristics of radio quiet zones".
[i.23] Regulation (EU) 2019/2144 of the European Parliament and of the Council of 27 November 2019
on type-approval requirements for motor vehicles and their trailers, and systems, components and
separate technical units intended for such vehicles, as regards their general safety and the
protection of vehicle occupants and vulnerable road users, amending Regulation (EU) 2018/858 of
the European Parliament and of the Council.
[i.24] ITU-R Radio Regulations: 2024 Edition.
[i.25] Y. X. Gong, R. Mittra, L. Zhen, W. H. Yu, J. T. Jiang and W. Z. Shao: "Edge treatment for
TM
sidelobe reduction of parabolic reflector antenna with a two-layer absorber," 2011 IEEE
International Symposium on Antennas and Propagation (APSURSI), Spokane, WA, USA, 2011,
pp. 2184-2186, doi: 10.1109/APS.2011.5996946.
[i.26] P. Lam, Shung-Wu Lee, K. Lang and D. Chang: "Sidelobe reduction of a parabolic reflector with
TM
auxiliary reflectors," in IEEE Transactions on Antennas and Propagation, vol. 35, no. 12,
pp. 1367-1374, December 1987, doi: 10.1109/TAP.1987.1144056.
[i.27] Bo Sun, Jinghui Qiu, Caitian Yang and Lingling Zhong: "Effect of design parameters on sidelobe
level of short-focus parabolic reflector antenna," 2008 Asia-Pacific Symposium on
th
Electromagnetic Compatibility and 19 International Zurich Symposium on Electromagnetic
Compatibility, Singapore, 2008, pp. 851-854, doi: 10.1109/APEMC.2008.4560009.
[i.28] Recommendation ITU-R SA.509-3 (2013): "Space research earth station and radio astronomy
reference antenna radiation pattern for use in interference calculations, including coordination
procedures, for frequencies less than 30 GHz".
[i.29] Recommendation ITU-R SA.1811-0 (2007): "Reference antenna patterns of large-aperture space
research service earth stations to be used for compatibility analyses involving a large number of
distributed interference entries in the bands 31.8-32.3 GHz and 37.0-38.0 GHz".
[i.30] Recommendation ITU-R P.526-15 (2019): "Propagation by diffraction".
[i.31] Recommendation ITU-R RA.1513-1: "Levels of data loss to radio astronomy observations and
percentage-of-time criteria resulting from degradation by interference for frequency bands
allocated to the radio astronomy on a primary basis".
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8 ETSI TR 104 098 V1.1.1 (2025-05)
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
avoidance zone: Defined in [i.10].
coordination area: Defined in [i.9], and further definition in [i.24].
coordination zone: Defined in [i.5].
exclusion zone: Defined in [i.5] and [i.12].
radio quiet zone: Defined in [i.22].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
λ wavelength
Θ elevation angle or polar angle
Φ azimuth angle
η antenna efficiency
d Path length from top of barrier to effective center of antenna
d Path length from top of barrier to transmitter
d'1 Actual distance on a straight line between barrier and telescope; approximately d1
d'2 Actual distance on a straight line between barrier and telescope; approximately d2
dB deciBel
dBi gain in deciBels relative to an isotropic antenna
dBm gain in deciBels relative to one milliwatt
D diameter RAS antenna
f centre frequency
C
h Height above reference level of the effective center of the antenna
a
h Height above reference level of the barrier
b
h Effective height of barrier: approximated by h -h for d ≫d
m b a 2 1
J(v) Diffraction loss
Ic compensated interference
Inc non- compensated interference
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ADAS Advanced Driver Assistance System
CEPT European Conference of Post and Telecommunications administrations
CRAF Committee on Radio Astronomy Frequencies
ECA European Common Allocations table
ECC Electronic Communications Committee
EIRP Equivalent Isotropic Radiated Power
ERC European Radiocommunication Committee
EU European Union
ITU-R International Telecommunication Union - Radio sector
LOS Line Of Sight
RAS Radio Astronomy Service
RF Radio Frequency
RR ITU-R Radio Regulations
SRD/MG Short Range Devices/Maintainance Group
SRR Short Range Radar
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9 ETSI TR 104 098 V1.1.1 (2025-05)
UWB Ultra Wideband Technology
WG FM CEPT Working Group Frequency Management
WG SE CEPT Working Group Spectrum Engineering
4 Regulatory frameworks and other background
information
4.1 Spectrum allocations in the range 77 - 81 GHz in CEPT
4.1.1 European Common allocations table
Table 1 provides information about the spectrum allocations in the range 77 - 81 GHz, information is extracted from
ERC Report 025 [i.3].
Table 1: Extract from European Common allocations table
(Source: ERC Report 025 [i.3])
Frequency band RR Region 1 Allocation and RR footnotes European Common Allocation and ECA
applicable to CEPT Footnotes
76 GHz - 77,5 GHz RADIO ASTRONOMY RADIO ASTRONOMY
RADIOLOCATION RADIOLOCATION
Amateur Amateur
Amateur-Satellite Amateur-Satellite
Space Research (space-to-Earth) Space Research (space-to-Earth)
5.149 5.149
77,5 GHz - 78 GHz AMATEUR AMATEUR
AMATEUR-SATELLITE AMATEUR-SATELLITE
RADIOLOCATION 5.559B RADIOLOCATION 5.559B
Radio Astronomy Space Research (space-to-Earth)
Space Research (space-to-Earth) 5.149
5.149
78 GHz - 79 GHz RADIOLOCATION RADIOLOCATION
Amateur Amateur
Amateur-Satellite Amateur-Satellite
Radio Astronomy Radio Astronomy
Space Research (space-to-Earth) Space Research (space-to-Earth)
5.149 5.149
5.560 5.560
79 GHz - 81 GHz RADIO ASTRONOMY
RADIO ASTRONOMY
RADIOLOCATION RADIOLOCATION
Amateur Amateur
Amateur-Satellite Amateur-Satellite
Space Research (space-to-Earth) 5.149
5.149
4.1.2 Relevant footnotes
4.1.2.1 Introduction
The texts of the relevant footnotes that are referred to in Table 1, are given below. The text of the footnotes was
extracted from ERC Report 025 [i.3].
• Clause 4.1.2.2; ERC Report 025 [i.3], footnote 5.149.
• Clause 4.1.2.3; ERC Report 025 [i.3], footnote 5.559B.
• Clause 4.1.2.4; ERC Report 025 [i.3], footnote 5.560.
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10 ETSI TR 104 098 V1.1.1 (2025-05)
4.1.2.2 Footnote 5.149
The following text is a citation from ERC Report 025 [i.3]:
"In making assignments to stations of other services to which the bands: 13360-13410 kHz, 25550-25670 kHz, 37.5-
38.25 MHz, 73-74.6 MHz in Regions 1 and 3, 150.05-153 MHz in Region 1, 322-328.6 MHz, 406.1-410 MHz, 608-614
MHz in Regions 1 and 3, 1330-1400 MHz, 1610.6-1613.8 MHz, 1660-1670 MHz, 1718.8-1722.2 MHz, 2655-2690 MHz,
3260-3267 MHz, 3332-3339 MHz, 3345.8-3352.5 MHz, 4825-4835 MHz, 4950-4990 MHz, 4990-5000 MHz, 6650-
6675.2 MHz, 10.6-10.68 GHz, 14.47-14.5 GHz, 22.01-22.21 GHz, 22.21-22.5 GHz, 22.81-22.86 GHz, 23.07-23.12 GHz,
31.2-31.3 GHz, 31.5-31.8 GHz in Regions 1 and 3, 36.43-36.5 GHz, 42.5-43.5 GHz, 48.94-49.04 GHz, 76-86 GHz, 92-
94 GHz, 94.1-100 GHz, 102-109.5 GHz, 111.8-114.25 GHz, 128.33-128.59 GHz, 129.23-129.49 GHz, 130-134 GHz,
136-148.5 GHz, 151.5-158.5 GHz, 168.59-168.93 GHz, 171.11-171.45 GHz, 172.31-172.65 GHz, 173.52-173.85 GHz,
195.75-196.15 GHz, 209-226 GHz, 241-250 GHz, 252-275 GHz are allocated, administrations are urged to take all
practicable steps to protect the radio astronomy service from harmful interference. Emissions from spaceborne or
airborne stations can be particularly serious sources of interference to the radio astronomy service (see Nos. 4.5 and
4.6 and Article 29). (WRC-07)"
4.1.2.3 Footnote 5.559B
The following text is a citation from ERC Report 025 [i.3]:
"The use of the frequency band 77.5-78 GHz by the radiolocation service shall be limited to short-range radar for
ground-based applications, including automotive radars. The technical characteristics of these radars are provided in
the most recent version of Recommendation ITU-R.M.2057. The provisions of No. 4.10 do not apply. (WRC-15)".
4.1.2.4 Footnote 5.560
The following text is a citation from ERC Report 025 [i.3]:
"In the band 78-79 GHz radars located on space stations may be operated on a primary basis in the Earth exploration-
satellite service and in the space research service."
4.2 Regulatory framework for ground based vehicular radar
operating in 77 - 81 GHz in CEPT
ECC/DEC/(04)03 [i.1] currently states under Considering l) and Decides 2) that automotive radar in 77 - 81 GHz is
operating on a non-protection/ non-interference basis.
The current regulation in ECC/DEC/(04)03 [i.1] was developed in 2004 based on the studies provided in ECC
Report 056 [i.2]. In the studies in ECC Report 056 [i.2] it was assumed that the parameters of the at that time available
24 GHz UWB radars could also be used for 79 GHz automotive radars, because the envisaged use cases focussed on
short range radars. When the regulation was published in 2004 no automotive radar sensors operating in the 79 GHz
band were available. ECC/DEC/(04)03 [i.1] has not been revised since then.
Within the last 20 years, RF technology and radar signal processing evolved, so that now 79 GHz automotive radar
sensors can be realized that provide more functions and better RF performance than it was foreseen in 2004.
4.3 Regulatory framework for RAS in CEPT
Radio Astronomy Service in the 77-81 GHz frequency range is operating in some portions of the band on a primary
basis and in other portions on a secondary basis. The technical and operational characteristics and the RAS observing
techniques are provided in the CRAF "Handbook for Radio Astronomy [i.17]. The protection criteria for RAS are
provided in Recommendation ITU-R RA.769-2 [i.6] and Recommendation ITU-R RA.1513 [i.7].
RAS with a secondary allocation is still protected under Recommendation ITU-R 5.149 [i.3] and [i.24]:
"…administrations are urged to take all practicable steps to protect the radio astronomy service from harmful
interference…"). Nevertheless, any potential interference criteria for the vehicular radar due to coexistence with RAS
should reflect this difference in status.
Therefore, regulatory resolution for a less strict limit in the band 77,5 - 79 GHz could be considered.
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11 ETSI TR 104 098 V1.1.1 (2025-05)
4.4 Existing radio quiet zones around RAS sites based on
national regulation
In some European Countries there are radio quiet zones established around radio astronomy sites. The radio quiet zones
are based on individual national regulation. A list of these radio quiet zones is available on the CRAF website [i.4]. For
better reading the information is cited:
"Usually a radio quiet zone has been established around a radio astronomy station. Within such area motorized traffic
is severely restricted or forbidden, and there may be several severe restrictions on the use of electronic equipment and
on the existences of e.g. factories, buildings and construction works within that area: i.e. radio-quiet means quiet".
Table 2: Relevant for ground based vehicular radar are the following radio quiet zones
RAS Radius of radio Regulatory process
quiet zone
Metsähovi About 1 km The radio quiet zone has been established in consultation with the Finnish
national regulatory authority
Plateau de Bure 3 km for emitters Radio quiet zone established by the French national protection zone law since
December 2010
Pico Veleta 15 km Protected by a national law (https://www.boe.es/buscar/pdf/2014/BOE-A-2014-
4950-consolidado.pdf)
Yebes 11 km Protected by a national law (https://www.boe.es/buscar/pdf/2014/BOE-A-2014-
4950-consolidado.pdf)
4.5 RAS operation details
Before discussing new proposals for interference mitigation measures in clause 8 operating details of RAS stations in
the 77 - 81GHz band are summarized.
According to Recommendation ITU-R RA.314-9 [i.19], Table 1, only one spectral line of interest is located inside the
band 77 - 81 GHz, but according to Recommendation ITU-R RA.314-9 [i.19] Table 3, 77 81 GHz falls into one of the
preferred ranges for continuum observations. So, for the purpose of the present document only continuum observations
are considered.
Based on the available information in the RAS handbooks [i.17] and [i.18] it is assumed that certain regular mitigation
measures are already implemented today.
Below follows a summary of the applicability of the mitigation measures (in bold) described in Recommendation
ITU-R RA.2126-1 [i.20] as they apply to continuum observations (incoherent reception) and interference from ground
based radars:
1) The temporal excision could apply in case of interference with large temporal peaks and low values
otherwise. This hardly applies to ground based vehicular radar interference.
2) And (with some specific geographical situations exempted) since there is no clear singular direction for the
ground based vehicular radar interference spatial excision also hardly applies, though the observation track
planning technique described in clause 8.7 partially falls in this category.
3) Temporal cancellation applied to the incoherent detection performed by continuum observations is possible
however if multiple antennas are used to measure the desired signal or auxiliary receivers are used to
accurately estimate the interference. This is very similar to the technique described in Annex C to the present
document.
4) Post-correlation cancellation only applies to coherent RAS receivers.
5) Anti-coincidence mitigation may have some application to ground based vehicular radar interference, possibly
in combination with temporal cancellation.
According to publication [i.21] new interference mitigation methods for RAS using artificial intelligence are under
development.
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12 ETSI TR 104 098 V1.1.1 (2025-05)
NOTE: It is unclear which RAS mitigation measures from the list above and which mitigation level in dB was
included in ECC Report 350 [i.12], and which additional mitigation could be achieved by applying these
methods more extensively.
5 Earlier studies that deal with interference of radar
operating in 76 - 81GHz or parts thereof into the
radio astronomy service
5.1 Introduction
In the CEPT and ITU-R context, the following studies already consider the impact of radar operating in the frequency
range 76 - 81 GHz or parts thereof into RAS. For reference, the summary of the relevant clause of each document is
provided in the chapters below, for detailed information the full documents should be examined.
Following reports offer former studies:
• Clause 5.2: ECC Report 056 [i.2] - Compatibility of automotive collision warning Short Range Radar
operating at 79 GHz with radiocommunication services.
• Clause 5.3: ECC Report 222 [i.8] - The impact of Surveillance Radar equipment operating in the 76 to 79 GHz
range for helicopter application on radio systems.
• Clause 5.4: Report ITU-R M.2322 [i.9] - Systems characteristics and compatibility of automotive radars
operating in the frequency band 77,5 - 78 GHz for sharing studies.
• Clause 5.5: Report ITU-R RA.2457 [i.10] - Coexistence between the radio astronomy service and
radiolocation service applications in the frequency band 76 - 81 GHz.
5.2 Studies in ECC Report 056
The following text is a direct citation from the conclusion clause (clause 4) of ECC Report 056 [i.2].
"The technical feasibility of coexistence between automotive collision warning SRR and the radio astronomy service in
the frequency band around 79 GHz is dependent on the aggregated impact of SRR devices transmitting in the direction
of a radio astronomy station.
From the results based on the model used, with a maximum e.i.r.p. of -3 dBm/MHz per SRR device around 79 GHz, it is
concluded that regulatory measures (e.g. automatic deactivation mechanism close to radio astronomy observatory
stations) are necessary to enable the coexistence between SRR and the radio astronomy service.
…
It is further noted that Short Range Devices shall not cause harmful interference to a Radiocommunication service, in
particular if operating on a Primary basis".
5.3 Studies in ECC Report 222
The following text of the relevant section is a direct citation from the executive summary of ECC Report 222 [i.8].
from:
"This report presents the results of the compatibility studies performed on the impact of airborne surveillance radar in
the 76 to 79 GHz frequency range on radio systems and services.
…
ETSI
13 ETSI TR 104 098 V1.1.1 (2025-05)
Radioastronomy (co-channel)
Separation distances between 47 km and 98 km are required under worst case assumptions to protect the RAS stations
in Europe. The difference between the near field and medium range obstacle detection system is small (near field system
47-98 km, medium range system 57-98 km). The altitude of the helicopter has an essential impact on the separation
distance (altitude 300m: separation distance 98 km, altitude 0 m: separation distance 29 km. The above-mentioned
distances are derived for an effective antenna height on the radio astronomy site of 50 m. The effect of the terrain can
increase the size of the separation distances (e.g. 98 km could increase to 115 km) in case of RAS located in elevated
positions (or when the helicopter would fly at greater altitudes) or reduce it when the terrain offer shielding to the radio
astronomy site. It will be left to Administrations to identify, where necessary, the size and shape of the exclusion zone to
protect radio astronomy sites, by using appropriate digital terrain models.
The occurrence probability has also been analysed in this report. As a limit the data loss value of 2% from
Recommendation ITU-R RA.1513-1 maybe applicable as the percentage of lost observation packets each 2000 s period
over one day.
The simplest interpretation would be to restrict the helicopter radar activity around the RAS station to fulfil the 2 % per
day. This would mean a maximum on-time of 28.8 minutes a day, or about six Take-Offs and Landings per day
(assuming 5 minutes transmitter on-time each landing and take-off).
More detailed occurrence probability calculations are provided in addition considering assumptions on helicopter
deployment. As a result the occurrence probability shows a huge variance. …
It was not possible in this report to determine a representative result for the occurrence probability and exclusion zone.
Therefore, administrations should decide on a national level on the need for and the size of an exclusion zone.
…
No differentiation has been made between rescue (which is only a fraction of all operations) and non-rescue helicopter
missions in the above calculations, because this is seen as outside the scope of this report.
…".
5.4 Studies in Report ITU-R M.2322
The following text is a direct citation from the conclusion section (chapter 8) of Report ITU-R M.2322 [i.9]:
"Theoretical studies and observations indicated that the required separation distance between automotive radars and
incumbent services could range from less than 1 km to up to 42+km, depending on the interference scenario and
deployment environment. These results were based on worst-case assumptions and did not take into account the effects
of terrain shielding, terrain occupation and the implementation of mitigation techniques to reduce the possibility of
interference to incumbent services. When these factors are taken into account, the possibility of co-channel interference
to incumbent services from automotive radars is sufficiently low and manageable. Therefore, it can be concluded that in
the 77.5-78 GHz band, sharing is feasible between automotive radars and incumbent services.
It is expected that any potential cases of interference between automotive radars and incumbent services could be
addressed by mitigation factors such as terrain shielding, emission power limits and quiet zones. Some areas of concern
remain and may need to be further analysed and dealt with by administrations. It is anticipated that the radio
astronomers, radio amateurs and the automotive radar manufacturers will continue their cooperative effort to examine
and implement mitigation techniques that can be employed to address potential interference concerns".
5.5 Studies in Report ITU-R RA.2457
The following text is a direct citation from the summary section (chapter 7) of Report ITU-R RA.2457 [i.10]:
"This Report provides sharing and compatibili
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