ETSI TR 104 139 V1.1.1 (2025-08)

Use of innovative antenna systems within millimetre Wave Transmission and impacts on standards and regulations

DTR/ATTMTMmWT-0027

General Information

• Status: Not Published
• Technical Committee: ATTM TM_mWT - Millimeter Wave Transmission
• Current Stage: 12 - Citation in the OJ (auto-insert)
• Due Date: 15-Aug-2025
• Completion Date: 12-Aug-2025

Standards Content (Sample)

TECHNICAL REPORT
Use of innovative antenna systems within
millimetre Wave Transmission and
impacts on standards and regulations

2 ETSI TR 104 139 V1.1.1 (2025-08)

Reference
DTR/ATTMTMmWT-0027
Keywords
antenna, backhaul, millimetre wave, mWT,
transmission
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ETSI
3 ETSI TR 104 139 V1.1.1 (2025-08)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Executive summary . 4
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Antenna classification and definitions. 9
5 High directivity detachable antennas at mmW . 10
5.1 ETSI antenna classes . 10
5.1.1 Point to point systems . 10
5.1.2 Point to Multipoint systems . 10
5.2 New high directivity antennas . 11
5.2.1 High space-selectivity (ETSI class) antenna systems . 11
5.2.2 Electro-mechanical alignment-tracking antenna systems . 12
6 Integrated non-detachable antennas at mmW . 14
6.1 Passive integrated antennas . 14
6.2 Active integrated antennas . 14
6.2.1 General concept . 14
6.2.2 Static active integrated antennas . 16
6.2.3 Time varying active integrated antennas . 18
6.2.4 Consideration on the geometrical shape of the antenna . 21
6.2.5 Electrical alignment-tracking antenna systems . 21
7 Dual band antennas for BCA . . 21
7.1 BCA concept . 21
7.2 Dual band antenna . 22
8 New architectures with separated TX and RX antennas . 23
8.1 Architecture . 23
8.2 DREAM project . 24
8.3 Flexible FDD (fFDD) . 25
8.4 Full duplex. 28
9 Implications of integrated antennas on system requirements . 30
9.1 Systems with equivalent virtual antenna connector . 30
9.2 Systems without equivalent virtual antenna connector. 30
10 Implications of integrated antennas on system testing . 30
10.1 Test bench for radiated measurements . 30
10.2 Radiated RX test bench . 30
10.3 Radiated TX test bench . 31
11 Conclusions . 32
Annex A: Change history . 34
History . 35

ETSI
4 ETSI TR 104 139 V1.1.1 (2025-08)
Intellectual Property Rights
Essential patents
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pertaining to these essential IPRs, if any, are 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
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Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Access, Terminals, Transmission and
Multiplexing (ATTM).
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.
Executive summary
The present document deals with innovative technologies applicable to mmW transmission for what regards the antenna
system. The traditional approach in MW transmission equipment is to have a TRX connected to an antenna by means of
a connector which represents the reference point for requirement setting and for measurement of conformance. Antenna
technology is evolving in different directions: on one side in the traditional way by achieving higher directivity to allow
a greater system gain, on other sides by employing new architectures such as separated TX and RX antennas, active
antennas and/or antennas integrated with the equipment.
Proper classification and terminology of antenna types is considered in clause 4.
Clauses 5 and 6 of the present document analyse high directivity detachable antennas and integrated non-detachable
antennas in order to investigate the two most promising directions of innovation in antenna technology.
Dual band antennas to be used by systems employing Band and Carrier Aggregation (BCA) are considered in clause 7.
ETSI
5 ETSI TR 104 139 V1.1.1 (2025-08)
Clause 8 takes into account the possible new architectures when separated TX and RX antennas are used without the
need for a duplex filter (FDD systems) or a switch (TDD systems); this opens the way to possible new duplex schemes
such as flexible FDD (fFDD), with the possibility to flexibly define the distance in frequency between TX and RX, or
even Full Duplex (FD). This new architecture is particularly interesting when going to high frequencies as in D band
where, leveraging on the short wavelength, compact antenna systems can be implemented, possibly with multiple
antennas in one equipment. The impact on radio planning and spectrum regulation is considered as well.
Whilst high directivity detachable antennas do not change the way system requirements are set and conformance
measurements are done apart from the definition of ever stricter antenna mask classes, integrated non-detachable
antenna systems raise the important issues of how to define system requirements and how to measure the conformance
to them, since an antenna connector is not any more available. In this case a paradigm shift is needed from conducted to
radiated requirements, with accordingly defined measurements. These aspects are taken into account respectively in
clauses 9 and 10.
Introduction
The present document deals with innovative technologies applicable to mmW transmission for what regards the antenna
system. The different types of antennas that can be used in MW and mmW systems can be classified according to
different features, such as:
• Detachable vs. non-detachable, where a non-detachable antenna is one fully integrated with the rest of the
equipment.
• Passive vs active, where an active antenna is one containing active components able to modify amplitude
and/or phase of the input signal.
• Time variant vs static, where a time variant antenna is one with radiated pattern changing in time during
working conditions.
The traditional antenna used in MW radio links for Fixed Service is a passive detachable one, where system
requirements are defined and verified at the antenna connector; the antenna is characterized by parameters like gain,
bandwidth and loss and represented by its radiation pattern in space. Harmonised standards have been developed at
ETSI for PtP [i.1] and PtMP [i.2] systems within this logical frame, where the antenna part is dealt with in related ETSI
standards [i.3], [i.4].
Innovation in passive, detachable antenna has directed towards ever improving directivity according to progressively
more stringent antenna masks as defined by ETSI standards [i.3], [i.4], going in time from class 1 to class 4 types for
PtP systems and from DN1 to DN5 for PtMP systems and possibly over.
When going towards frequencies in the mmW range the increasingly shorter wavelength makes antenna integration into
the equipment feasible and advantageous from both technical and cost sides. In particular when considering D band
(130 - 174,8 GHz range) the possibility to design a compact radio unit with integrated antennas has been already
demonstrated with some prototypes and several research activities are ongoing on the subject. One prototype with
passive, non-detachable and distinct TX and RX antennas was deployed in Milan in November 2016 for propagation
investigations in D band [i.5]. Another prototype with active, integrated antennas was developed within the Horizon
2020 framework as well [i.6].
A great push towards the development of innovative antenna systems is coming from the introduction into IMT-2020 of
Active Antenna Systems (AAS), which employ antenna array structure with active elements within the antenna in order
to control the amplitude and phase of the signals to the single elements of the array. In this way beamforming is
possible and the antenna pattern can be adaptively modified in time in order to adapt to the changing propagation
conditions and user distribution.
When considering a non-detachable antenna, whether passive or active, the problem of defining the system
requirements and their measurement requires a paradigm shift, since it is necessary to pass from conducted to radiated
requirements and measurements. This change requires the measurements to be done in a controlled environment such as
an anechoic chamber so to avoid any unwanted influence from the surrounding environment. A good reference is the
work done in 3GPP for IMT2020 systems and implemented in the related ETSI standards as well [i.14].
ETSI
6 ETSI TR 104 139 V1.1.1 (2025-08)
The present document investigates the use of innovative antenna systems within millimetre Wave transmission and
impacts on standards and regulations. Clause 4 considers the classification and related terminology of antenna types. In
clause 5 evolution along the traditional path of passive, detachable antenna is considered, whilst clause 6 analyses the
integrated antenna evolution path, both sections dealing with technological aspects. Clause 7 takes into account the dual
band antennas that are developed within the concept of BCA [i.9], [i.17], where an antenna able to effectively handle
signals at two different bands is required. Clause 8 analyses the impacts on spectrum management and regulation of the
innovative architectures allowed when using distinct TX and RX antennas, where concepts such as fFDD and full
duplex become feasible. Finally clauses 9 and 10 take into consideration the impacts on requirement setting and
conformance measurement.
ETSI
7 ETSI TR 104 139 V1.1.1 (2025-08)
1 Scope
The present document deals with innovative technologies applicable to mmW transmission for what regards the antenna
system.
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 may be useful in implementing an ETSI deliverable or add to the reader's
understanding, but are not required for conformance to the present document.
[i.1] ETSI EN 302 217-2: "Fixed Radio Systems; Characteristics and requirements for point-to-point
equipment and antennas; Part 2: Digital systems operating in frequency bands from 1 GHz to
174,8 GHz; Harmonised Standard for access to radio spectrum".
[i.2] ETSI EN 302 326-2: "Fixed Radio Systems; Multipoint Equipment and Antennas; Part 2:
Harmonised Standard for access to radio spectrum".
[i.3] ETSI EN 302 217-4: "Fixed Radio Systems; Characteristics and requirements for point-to-point
equipment and antennas; Part 4: Antennas".
[i.4] ETSI EN 302 326-3: "Fixed Radio Systems; Multipoint Equipment and Antennas; Part 3:
Multipoint Antennas".
[i.5] Luini L., Roveda G., Zaffaroni M., Costa M., Riva C. (2018): "EM wave propagation experiment
at E band and D band for 5G wireless systems: preliminary results". Proceeding of EuCAP 2018,
9-13 April 2018, pp. 1-5, London, UK.
[i.6] M. Frecassetti et al.: "SiGe:BiCMOS technology is enabling D-band link with Active Phased
Antenna Array", 2021 Joint European Conference on Networks and Communications & 6G
Summit (EuCNC/6G Summit).
[i.7] ECC Report 342: "Microwave Point-to-Multipoint technologies based on active antennas for 5G
backhaul above 27.5 GHz".
[i.8] Recommendation ITU-R M.2101-0 (2017): "Modelling and simulation of IMT networks and
systems for use in sharing and compatibility studies".
[i.9] ECC Report 320: "Band and Carrier Aggregation in fixed point-to-point systems".
[i.10] ECC Recommendation (18)01: "Radio frequency channel/block arrangements for Fixed Service
systems operating in the bands 130-134 GHz, 141-148.5 GHz, 151.5-164 GHz and
167-174,8 GHz".
[i.11] Roveda G., Costa M. (2018): "Flexible Use of D Band Spectrum for 5G Transport: a Research
Field Trial as Input to Standardization". Proceeding of PIMRC 2018, 9-12 September 2018,
Bologna, Italy.
ETSI
8 ETSI TR 104 139 V1.1.1 (2025-08)
[i.12] ETSI EN 301 126-1: "Fixed Radio Systems; Conformance testing; Part 1: Point-to-point
equipment - Definitions, general requirements and test procedures".
[i.13] ETSI EN 301 126-3-1: "Fixed Radio Systems; Conformance testing; Part 3-1: Point-to-Point
antennas; Definitions, general requirements and test procedures".
[i.14] ETSI TS 137 145-2: "Universal Mobile Telecommunications System (UMTS); LTE; 5G; Active
Antenna System (AAS) Base Station (BS) conformance testing; Part 2: radiated conformance
testing (3GPP TS 37.145-2)".
[i.15] ETSI EN 302 217-1: "Fixed Radio Systems; Characteristics and requirements for point-to-point
equipment and antennas; Part 1: Overview, common characteristics and requirements not related to
access to radio spectrum".
[i.16] ETSI EN 301 126-4: "Fixed Radio Systems; Conformance testing; Part 4: Definitions, general
requirements and test procedures for radiated tests for point-to-point equipment and antenna".
[i.17] ETSI GR mWT 015: "Frequency Bands and Carrier Aggregation Systems; Band and Carrier
Aggregation".
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void.
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
rd
3GPP 3 Generation Partnership Project
AAS Active Antenna System
BCA Band and Carrier Aggregation
EIRP Equivalent Isotropic Radiated Power
FD Full Duplex
FDD Frequency Division Duplex
fFDD flexile FDD
FS Fixed Service
HPBW Half Power Beam Width
IMT-2020 International Mobile Telecommunications-2020
mmW millimetre Wave
MW MicroWave
PoP Point of Presence (of optical fibre)
PtMP Point to MultiPoint
PtP Point to Point
QoS Quality of Service
RF Radio Frequency
RPE Radiation Pattern Envelope
RSL Received Signal Level
RX Receiver
TDD Time Division Duplex
TRX Transmitter and Receiver (Transceiver)
TX Transmitter
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9 ETSI TR 104 139 V1.1.1 (2025-08)
4 Antenna classification and definitions
Antennas can be classified according to several different criteria and parameters. They can be:
• Detachable or non-detachable according to the presence or not of an antenna connector available for
conformance testing.
• Active or passive considering the presence or not of active components that may impact the antenna behaviour
within the antenna itself (e.g. amplifiers, phase shifters, switches, etc.).
• Single-beam or multi-beam considering the presence in the radiated pattern of one or more main beams.
• Single frequency band or multi-band according to the emission spectrum being in one or more bands.
• With or without beam-forming capability according to the possibility to modify the radiated pattern.
• Static or time-variant according to the constant or variable radiated pattern in time during working conditions.
The different types of antennas can be a combination of this classification criteria; one example is the traditional Fixed
Service MW parabolic antenna that is detachable, passive, single beam, single frequency, without beam-forming and
static; another example is the AAS of a mobile system that is non-detachable, active, multi-beam, single frequency, with
beamforming and time variant.
For what regards the present document the main important consideration is the availability of an antenna connector in
the equipment, because this is the discriminant between the possibility to set the requirements and conformance testing
in a "conductive" way and the necessity to develop them in a "radiated" way.
In the "conductive" way a measurement instrument can be connected directly to the antenna connector of the equipment
instead of the antenna. This is the current situation for FS equipment in ETSI EN 302 217-1 [i.15], where the antenna
connector is well defined as shown in Figure 1 at section C/C'.

Figure 1: ETSI system block diagram with antenna connector D
In the "radiated" way the measurement is to be done on the integral equipment including its own antenna, with the
instrument connected to its own antenna and both equipment and instrument placed into a controlled environment such
as an anechoic chamber. This is a new situation for FS equipment to be properly studied, in particular when considering
mmW frequencies where the sensitivity of measurement instruments is a critical issue.
It is worthwhile to note that in some cases even if an integrated antenna could be physically separated from the radio
part, nevertheless when control signals are needed to the antenna part in order for it to work properly this case should be
considered as non-detachable as well.
ETSI
10 ETSI TR 104 139 V1.1.1 (2025-08)
A comparison among different models is shown in next clause on the base of experimental data.
5 High directivity detachable antennas at mmW
5.1 ETSI antenna classes
5.1.1 Point to point systems
ETSI Harmonised Standards for Fixed Service ([i.3], [i.4]) classify the different types of antennas according to well
defined masks in the space domain defining different antenna classes, according to the frequency range, the azimuth or
elevation direction and the co-polar or cross-polar behaviour.
In the case of PtP systems (ETSI EN 302 217-4 [i.3]) and with respect to the Radiation Pattern Envelope (RPE) four
classes (RPE classes 1 to 4) have been defined in the co-polar case and azimuth plane, summarized in Table 1.
Table 1: Corner points of co-polar limits for actual RPE templates

The antenna classes define the directional properties of the antenna, the higher the class the higher the directivity of the
antenna and the lower the interference impact to be considered in network planning.
5.1.2 Point to Multipoint systems
Similar classes have been defined for PtMP systems (ETSI EN 302 326-3 [i.4]) for the different types of antennas used
(directional, sectorial and omnidirectional), in line with the principle that antennas with more demanding maximum
combined co-polar and cross-polar RPEs have higher class numbers:
• Directional antennas have 5 classes, from DN1 to DN5.
• Single-beam sectoral antennas have 4 classes, from SS1 to SS4.
• Multi-beam sectoral antennas have 2 classes, MS1 and MS2.
• Omnidirectional antennas are not differentiated in classes.
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11 ETSI TR 104 139 V1.1.1 (2025-08)
5.2 New high directivity antennas
5.2.1 High space-selectivity (ETSI class) antenna systems
Technology evolution in detachable antennas and ever-increasing requirements in terms of interference handling will
bring new antenna systems with possibly higher classes than current ETSI most demanding ones.
As operational frequencies increase there is a requirement for interference mitigation using higher class RPE's, such as
class 4, to allow for better spectrum utilization and improving link density. To illustrate antenna performance relative to
a class 4 mask, an example of measurement is shown for class 4 at 42 GHz band (Figure 2).
SHP2-42
-10
-20
-30
-40
-50
-60
-70
-80
-150 -100 -50 0 50 100 150
Azimuth (°)
Figure 2: Measured Co-Pol radiation pattern for 2ft antenna @ 42 GHz - ETSI Class 4 RPE
At this point in time class 3 at E-Band is generally considered as the 'standard' (an example of measurement is shown in
Figure 3), but going forward there is a potential requirement for class 4 at E-Band (an example of simulation is shown
in Figure 4), which can be attributed to expanding growth/densification of backhaul systems at E-Band. Comparing
Figure 3 and Figure 4 it can be clearly seen the significant improvement in side-lobe performance that a class 4 antenna
has over a class 3.
ETSI
12 ETSI TR 104 139 V1.1.1 (2025-08)

Figure 3: Measured Co-Pol radiation pattern 2ft antenna @ E-Band - ETSI Class 3 RPE
)
B
d
(
e
d
u
t
i
l
p
m
A
Figure 4: Simulated Co-Pol radiation pattern 2ft antenna @ E-Band - ETSI Class 3 (red) &
4 (magenta) RPEs
5.2.2 Electro-mechanical alignment-tracking antenna systems
As long as the directivity of the antenna is increased the issue of maintaining the alignment of the link with pole
swaying and/or bending due to thermal and/or wind reasons becomes more relevant.
ETSI
13 ETSI TR 104 139 V1.1.1 (2025-08)
The entity of antenna swaying and bending depends on several factors:
• Atmospheric situation (temperature variation, wind speed).
• Type of pole (mono-pole, roof-pole, mast, tower).
• Material and height of pole.
The reduction in Received Signal Level (RSL) becomes significant when the pole swaying angle becomes comparable
to the 3 dB beamwidth (HPBW) as shown in Figure 5; as a consequence the relevance of the issue grows with antenna
gain and with frequency.
Figure 5: Sway angle and HPBW
In Table 2 some typical values at 23 GHz and E band are shown.
Table 2: Typical values of HPBW
Antenna 3 dB Beam
30 cm 23 GHz 3° (±1,5°)
60 cm 23 GHz 1,7° (±0,85°)
30 cm 80 GHz 0,9° (±0,45°)
60 cm 80 GHz 0,5° (±0,25°)
In Figure 6 typical values of sway angles are shown.

Figure 6: Typical sway angle for different pole types
In case of deployment over a lamp pole the sway angle can be typically > 2°.
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14 ETSI TR 104 139 V1.1.1 (2025-08)
From the typical values shown in Table 2 and Figure 6 it is evident that the issue of maintaining link alignment becomes
relevant at high mmW, starting from E band and over.
Different systems which are able to control adaptively the link alignment can be considered:
• In traditional parabolic antennas an electro-mechanical adaptation of the orientation of the antenna can be
implemented.
• In phased array antennas link alignment can be maintained by leveraging on beam-steering (see clause 6.2.5).
The control mechanism has to be fast enough to be able to compensate for both swaying due to wind and bending due to
temperature variation.
6 Integrated non-detachable antennas at mmW
6.1 Passive integrated antennas
A passive integrated antenna is a non-detachable antenna without active components in it.
An example of this kind of antenna is the one used by the D band prototype operating at Politecnico of Milan since
November 2016 [i.5], which is an array antenna whose elements are fed by a passive distribution network in order to get
a fixed and directive RPE. This antenna is connected directly at the RF front end and is not detachable from the rest of
the system once the equipment is assembled.
In this type of antennas an equivalent antenna port can be defined with an equivalent gain even if a physical port is not
accessible; in this case by measuring the EIRP and knowing the declared antenna gain a TX power at the virtual antenna
port can be calculated.
6.2 Active integrated antennas
6.2.1 General concept
An active integrated antenna is a non-detachable antenna with active components within the antenna itself, with the
possibility to control the antenna pattern (beamforming) either only at initial configuration (fixed pattern) or during
operation (time-varying pattern).
A very well-known example of active integrated antenna is given by phased array systems in which the antenna is
constituted by a proper spatial distribution of radiating elements, the input signal to each one being controlled in
amplitude and phase by means of active components, namely amplifiers and phase shifters.
By controlling the amplitude and phase of the input signal to the antenna elements the generated radiation pattern can be
controlled and defined in what is known as beamforming; from the technological point of view beamforming can be
implemented in the analogue domain, in the digital domain or with a hybrid implementation.
In any case the produced radiation pattern is given by the product of two main factors:
• The element factor, which is the radiating pattern of a single element in the array and depends on the type of
radiating element chosen for the specific implementation; in the most common implementations the element
factor is the same for all antenna elements.
• The array factor, which is fully defined by the geometry of the array and the frequency of operation, which in
the common case of uniform distribution is just function of the number of elements and the element spacing as
related to the wavelength.
The boresight of the antenna is defined as the direction orthogonal to the antenna plane.
In order to understand the basics of the behaviour of phased array antennas the following simple assumptions can be
initially taken:
• The elements are equally spaced.
ETSI
15 ETSI TR 104 139 V1.1.1 (2025-08)
• The spacing between elements is half-wavelength.
• The amplitude of all elements is the same.
• The phase shift between elements is equal.
In this case the radiation pattern would be in the boresight direction, with small sidelobes decreasing according to a
sin(x)/x envelope. The higher the number of elements, the higher the number of sidelobes but the faster their attenuation
when going away from boresight and the narrower the beam-width.
The radiation pattern produced in this simplified case can be seen in Figure 7.

Figure 7: Normalized radiation pattern in simplified case with number of elements of 8, 16 and 32
In order to move the peak of RPE away from the boresight it is sufficient to modify the phases of the single elements,
producing what is known as beam-steering.
When shifting the beam away from the boresight the radiation pattern changes according to both the single element
pattern and the number of elements, but in general the wider the steering angle the lower the peak of the main beam and
the wider its beam-width.
The normalized radiation pattern with three steering angles is shown in Figure 8, where the effect of the element
pattern, reducing the main beam amplitude when shifting away from boresight, is not considered.
ETSI
16 ETSI TR 104 139 V1.1.1 (2025-08)

Figure 8: Normalized radiation pattern in simplified case with beam-steering (case of 32 elements)
Once understood the basic impact of the single parameters to the phased antenna radiation pattern, the simplified
assumptions taken at the beginning of the clause can be removed, adding degrees of freedom and complexity to the
behaviour of the antenna system.
For example if changing amplitude and phase of the signal given to the single elements, the radiation pattern can be not
only beam-steered but more in general beam-formed.
Also the element spacing can be in general different from half wavelength, taking into account the feasibility limitations
of the antenna array itself when considering mmW frequencies.
It is a well-known property of phased arrays that when using an element distancing larger than half wavelength,
constructive interference will happen in directions other from the boresight (spatial aliasing effect), becoming even
more significant when steering the beam: these peaks are known as grating lobes and are to be kept under control since
they represent radiated energy in unwanted directions.
In the case of uniform element spacing:
• for d > λ grating lobes can be seen in the visible zone (-90° < θ < +90°) even without any steering;
• for λ/2 < d < λ grating lobes enter the visible zone only when steering.
Given a maximum steering angle θ that the system has to fulfil, there is a maximum element spacing d that can be
max max
used to avoid the appearance of grating lobes in the steering zone:
d = λ/(1+sinθ )
max max
So there is a trade-off between the maximum steering angle and the element spacing that can be used in the design of
the phased array.
In even more complex antenna systems the distribution of the elements could in general be non-uniform and the
element pattern itself could be different for different elements.
6.2.2 Static active integrated antennas
An active integrated antenna is static in case the controls on active elements of the antenna are defined at the
configuration of the system and not changed any more during operation.
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An example of use of this kind of active antenna is given by a PtMP system with star topology in which the
beamforming capability is used at installation in order to direct the peaks of its RPE from a central point to the leaf
sites. With regard to a traditional PtMP system, where a passive sector antenna is used at the node in order to cover a
certain area where terminals are located, this new concept of PtMP employs an optimized RPE in order to maximize
SINR leveraging on beamforming and on interference cancellation technologies. The structure of such a PtMP system is
shown in Figure 9.
Figure 9: General structure of a PtMP system based on active integrated antenna
Considering as an example a sector 90° wide with 8 terminals to be connected to a central hub, the resulting RPE from
the hub is shown in Figure 10.

Figure 10: Example of overall RPE from a hub to a 90° sector with 8 terminals
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The main use case for this PtMP system is backhauling of mobile networks, where the trend of the optical fibre to reach
more and more in depth the extent of the mobile network generates the need for connecting the PoP of the fibre to the
locations of the base stations surrounding the PoP, as shown in Figure 11.

Figure 11: Topology evolution of backhaul network
The description of this innovative PtMP system can be found in ECC Report 342 [i.7].
6.2.3 Time varying active integrated antennas
An active integrated antenna is time varying in case the controls on active elements of the antenna are adaptively
changing during operation. In case only the phases are controlled there is beam-steering systems where the direction of
the main beam can be modified; in case both amplitudes and phases are controlled there is beam-forming systems where
the antenna pattern can be modified.
The AAS used in IMT-2020 is a good example of a time-varying active integrated antenna system. In an AAS the
antenna pattern is adaptively changing as a consequence of two main external factors:
• The propagation environment, in which reflections, diffractions and transmissions are in general depending on
time as long as the involved obstructing body is moving.
• The user equipment distribution in space, which in general is changing in time since the terminals are moving.
When dealing with Fixed Service the possibility of having one end of the link in movement is of course excluded.
Nevertheless the possibility of antenna systems adaptive with the changes in propagation environment can be
considered within Fixed Service, considering for example radio networks with mesh topology and real time
re-configurability.
The model used to describe analytically the antenna pattern of AAS is contained in Recommendation
ITU-R M.2101-0 [i.8]. The spherical coordinates of reference are described in Figure 12.
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Figure 12: Spherical coordinates for AAS
The M.2101 model foresees some input parameters that are defined by the specific design for both the single element
pattern and the composite antenna pattern, as reported in Table 3 and Table 4.
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Table 3: Element pattern for antenna array model

Table 4: Composite antenna pattern for beamforming

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Apart from the details that can be found in the referenced Recommendation, it can be noted that the main design
parameters required to describe the AAS pattern are the following:
• 3 dB bandwidth of single element (H and V).
• Front to back ratio of single element (H and V).
• Single element gain.
• Number of elements (H and V).
• Element spacing (H and V).
• Mechanical down-tilt.
6.2.4 Consideration on the geometrical shape of the antenna
The traditional antenna of a microwave PtP radio is of circular section and consequently its RPE has circular symmetry.
When dealing with innovative types of antennas the section may have in general a different shape, for example
rectangular or square in the case of phased array antennas; in these cases, the RPE has not circular symmetry and the
orientation of the antenna with respect to the reference coordinates is to be duly considered.
6.2.5 Electrical alignment-tracking antenna systems
As long as the directivity of the antenna is increased the issue of maintaining the alignment of the link with pole
swaying and/or bending due to thermal and/or wind reasons becomes more relevant (see clause 5.2.2).
When considering time varying active integrated antennas the alignment can be maintained leveraging on the beam-
steering feature, implementing a loop able to keep the beam alignment over the link.
7 Dual band antennas for BCA
7.1 BCA concept
Band and Carrier Aggregation (BCA) is a concept enabling an efficient use of the spectrum through a smart
aggregation, over a single physical link, of multiple frequency channels (in the same or different frequency bands) [i.9],
[i.17].
A logical scheme of the BCA, shown in Figure 13, includes a carrier aggregation engine and d
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