DUAL POLARIZED RADIATING DIPOLE ANTENNA
CROSS-REFERENCE
This application is based on French Patent Application No. FR1 058828 filed
October 27, 2010, the disclosure of which is hereby incorporated by reference thereto in
its entirety, and the priority of which is hereby claimed under 35 U.S.C. § 119.
TECHNICAL FIELD
This invention relates to the field of telecommunication antennas transmitting
radioelectric waves in the hyperfrequency range, using radiating elements.
In particular, the invention relates to a radiating element that will operate in any
frequency band, particularly in a low frequency band of a multiband antenna, like those
present particularly in telecommunication antennas. Such a radiating element can be
used equally well in a single band antenna and in a multiband antenna, called panel
antennas, particularly intended for use as cell phone applications.
BACKGROUND
Cell telephony uses miscellaneous frequency bands corresponding to different
known telecommunication systems. Several telecommunication systems are presently
used simultaneously, for example such as the "Global System for Mobile communications"
GSM (870-960 MHz), the "Digital Cellular System" DCS (1710-1880 MHz), and the
"Universal Mobile Telephone Service" UMTS (1900-2170 MHz). Multiband antennas
derived from the combination of several series of radiating elements belonging to
frequency bands in different telecommunication systems are used within a single antenna
chassis, in order to avoid increasing the number of previously installed antennas.
For example, there are two-frequency band or three-frequency band antennas in
which radiating elements assigned to each frequency are aligned either parallel to each
other according to a longitudinal periodic structure, for example staggered and alternating,
so as to create a similar radioelectric environment for all radiating elements corresponding
to the same frequency. These configurations significantly increase the width of the
antenna and degrade the radiation performances, at least for the highest frequency.
Two configurations are frequently used in order to make a two-frequency band
antenna operating in two distinct frequency bands with orthogonal polarisations.
A first so-called "side by side" configuration consists of a first alignment of
radiating elements formed by two orthogonal cross dipoles operating on a first frequency
band, and a second alignment of radiating elements formed by two orthogonal cross
dipoles operating on a second frequency band. The two rows are parallel to each other
and are separated by at least half a wavelength of the highest frequency band. This "side
by side" configuration has good performances, but the width of the antenna is too large.
The "side by side" configuration has developed towards a "colinear" configuration to
reduce the antenna width.
In a second so-called "colinear" (or "concentric") configuration, radiating elements
formed by four dipoles in a square formation are arranged concentrically to operate in a
first frequency band around elements formed by two radiating cross dipoles operating in a
second frequency band. All these elements are aligned along the same axis and are
placed above a reflector in a single chassis. This configuration is too large for a long
dipole length, and the external radiating element can disturb the adjacent radiating
elements.
For both types of configuration, there is a strabismus effect of the azimuth
diagram caused by asymmetry in the azimuth alignment plane of elements radiating at
high frequency. A strong degradation in cross polarisation is also observed in the ±60°
angular section due to this asymmetry.
SUMMARY
New services are more demanding in terms of passband and they require the
highest possible gain and very high isolation levels between radiating elements in a more
compact environment, particularly to satisfy digital signal processing requirements.
Therefore, the purpose of this invention is to disclose a dual polarised radiating
element that can be integrated into a multiband antenna in colinear configuration leading
to a low cost, easily assembled and compact structure.
Another purpose of the invention is to disclose a dual polarised radiating element
capable of operating in a given frequency range with specific radiating characteristics in
the azimuth.
Another purpose of the invention is to disclose a dual polarised radiating element
operating in one frequency band, in which the geometry of the element has a limited
impact on the performances of another radiating element concentric with it and operating
in another frequency band.
Another purpose of the invention is to disclose the narrowest possible antenna
designed with this radiating element.
The purpose of this invention is a dual polarised radiating element comprising
four dipoles each comprising one stand and two arms. A first arm and a second arm
belonging to two adjacent dipoles forming a straight radiating strand composed of a single
part, the four radiating strands being arranged so as to form a disjoint square at the
corners. The two arms of each dipole are thus orthogonal to each other,
In this configuration, the dipoles are deliberately isolated from each other to
reduce inter-modulation problems. The shape of the radiating elements is designed so as
to obtain excitation that is as eccentric as possible, in order to achieve a networking effect.
According to one preferred embodiment, each of the radiating strands is
composed of a single conducting part with folded prolongations at each end of the
radiating strand.
The prolongations of each conducting part are preferably folded at 90° from the
plane of the radiating strands.
According to one aspect, at least one of the prolongations of each part forms a
half-stand of the stand of one of the dipoles.
According to another aspect, each dipole is powered by a power supply system
comprising a power supply line and at least one ground plane that is one of the halfstands
of the stand of one of the dipoles.
According to a first variant, the power supply system for a dipole with a stripline
structure is formed from a power supply line surrounded by two ground planes, each
ground plane being one of the half-stands of the stand of one of the dipoles.
A stripline or microstrip type power supply line arranged vertically reduces costs
and simplifies the assembly relative to the known radiating elements.
According to a second variant, the power supply system for a dipole has a
microstrip structure formed from a power supply line adjacent to a ground plane that is the
stand of the contiguous dipole.
The invention also discloses a radiating device comprising a first radiating
element operating in a first frequency band like that described above, and at least one
second radiating element operating in a second frequency band and comprising at least
one dipole, arranged at the centre of the square formed by the radiating strands of the first
radiating element, the radiating elements being arranged above a common reflector.
The invention also discloses an antenna comprising at least one first radiating
element operating in a first frequency band, like that described above, and at least one
second radiating element operating in a second frequency band. The first and second
radiating elements are aligned and arranged above a common reflector such that the
transverse strands of the first radiating elements are located between two adjacent
second radiating elements.
According to one variant embodiment, partitions may be arranged parallel to the
alignment of the second radiating elements, inside the alignment of the first radiating
elements.
According to another variant, parallelepiped, cubic or rectangular shaped cavities
are arranged around the second radiating elements, inside the alignment of the first
radiating elements.
The advantages of this invention are that it reduces the size and the space
occupied by multiband antennas, and particularly reduces the width by about 15%. It also
enables an improvement in RF performances while making the antenna symmetric.
Finally, it reduces costs and simplifies the assembly of the antenna.
DETAILED DESCRIPTION
Other characteristics and advantages of this invention will become clear after
reading the following detailed description of one embodiment, obviously given for
illustrative and non-limitative purposes, with reference to the appended drawings in which
- figure 1 diagrammatically shows a perspective view of an embodiment of a radiating
element,
- figure 2 diagrammatically shows a perspective view of a first embodiment of a radiating
element,
- figure 3 diagrammatically shows a perspective view of a second embodiment of a
radiating element,
- figure 4 diagrammatically shows a detail of the radiating device in figure 3 ,
- figure 5 diagrammatically shows a perspective view of one embodiment of an antenna,
- figure 6 diagrammatically shows a partial view of another embodiment of an antenna.
The drawings contain elements that can help to better understand the
description, and also to contribute to the definition of the invention. Identical elements in
each of these figures have the same reference numbers.
In the embodiment illustrated in figure 1, a radiating element 1 comprises four
dipoles 2, 3, 4, 5 . Each dipole 2, 3, 4, 5 comprises a stand 6, 7, 8, 9 each supporting a
pair of arms 2a, 2b ; 3a, 3b ; 4a, 4b ; 5a, 5b respectively. The two arms 2a, 2b ; 3a, 3b ;
4a, 4b ; 5a, 5b of each dipole 2, 3, 4, 5 are oriented to be perpendicular to each other.
Each stand 6, 7, 8, 9 comprises two half-stands 6a, 6b ; 7a, 7b ; 8a, 8b and 9a, 9b each
of which has one internal side face facing the other and one side face that faces outwards.
The colinear arms 2a and 5a belonging to dipoles 2 and 5 respectively form a
radiation strand 10 composed of a single straight conducting part, for example a thin metal
sheet, that prolongs on each end of the radiating strand 10. Consequently, the straight
radiating strand 10 is common to the two adjacent dipoles 2, 5 . Each prolongation of the
conducting part is folded to form the half-stands 6a and 9a of the stands 6 and 9 of the
dipoles 2 and 5 , respectively. Similarly, the colinear arms 2b and 3b of dipoles 2 and 3
respectively form a radiating strand 1 1 , each folded prolongation of the conducting part
forming the half-stands 6b and 7b of the stands 6 and 7 of dipoles 2 and 3 respectively.
Also similarly, the colinear arms 3a and 4a of the dipoles 3 and 4 respectively form a
radiating strand 12, each folded prolongation of the conducting part forming halfstands
7a and 8a of stands 7 and 8 of dipoles 3 and 4 respectively. Also similarly, the
colinear arms 4b and 5b of dipoles 4 and 5 respectively form a radiating strand 13, each
folded prolongation of the conducting part forming half-stands 8b and 9b of
stands 8 and 9 of dipoles 4 and 5 respectively. For example, the radiating
strands 10, 11, 12, 13 may be composed of thin folded metal sheets that are identical to
each other. The radiating strands 10, 11, 12, 13 are arranged so as to form a disjoint
square at the corners, the length L of each side of the square can vary from a quarter to a
half wavelength of the central operating frequency of the radiating element 1.
Power supply systems for dipoles 2, 3, 4, 5 have stripline structure composed of
a power supply line 14, 15, 16, that is the conducting layer placed between two ground
planes, from which it is separated by a dielectric layer. The power supply lines 14, 15, 16
are located at the four corners of the interrupted square delimited by the four radiating
strands 10, 11, 12, 13. The diagonally opposite power supply lines 14 and 16 generate
the same polarisation, in the present case at ±45°. The symmetry of the power supply
makes the radiation diagram symmetry. The half-stands 7a and 8a are shown as being
transparent in figure 1 so that the power supply lines 15 and 16 can be seen, to facilitate
understanding. The power supply line 15 is a conducting layer that is arranged between
the half-stands 7a and 7b of the stand 7 of the dipole 3 that act as the ground plane.
Similarly, each power supply system is composed of a power supply line 14, 15, 16, that is
the conducting layer, arranged between the half-stands 6a, 6b ; 8a, 8b ; 9a, 9b forming
the stands 6, 8 and 9 of the dipoles 2, 4 and 5 respectively, in pairs. The half-stands
6a, 6b ; 8a, 8b ; 9a, 9b act as the ground plane for the conducting layer that they
surround. Note that the radiating strands 10, 11, 12, 13 are disjoint and are separated by
a space, the width of which can be consolidated by inserting isolating packing parts 17, for
example made of plastic, thus separating the conducting parts from each other. The
difference is preferably kept constant so to achieve reproducible performances.
The power supply lines 14, 15, 16 are connected to four opposite coaxial cables,
and are coupled in pairs using a power splitter, so as to generate two orthogonal
polarisations. The prolongations of each conducting part forming the halfstands
6a, 6b ; 7a, 7b ; 8a, 8b ; 9a, 9b, respectively, are folded at 90° from the plane 18
of the radiating strands 10, 11, 12, 13. The power supply lines 14, 15, 16 thus extend
vertically between the reflector 19, acting as the ground plane for the radiating element 1
located in it, and one of the ends of each of the corresponding radiating
strands 10, 11, 12, 13 of the radiating element The vertically of the power supply
lines 14, 15, 16 contributes to preventing interactions between the radiating element 1 and
adjacent radiating elements. The radiating element 1 has a significant advantage in terms
of cost because it uses mainly thin metal sheets, cut out and folded identically, and
inexpensive and easily assembled stripline power supply systems.
The radiating element was made with a front-to-back ratio of more than 25 dB,
cross polarisation of more than 15 dB along the line of the antenna, and a mid-power
aperture in azimuth of 65°. However, it is perfectly possible to use it for an application for
which the mid-power aperture would be 90°.
We will now consider figure 2 that shows a first embodiment of a two-frequency
band radiation device 20 comprising a radiating element 2 1 operating for example in a low
frequency LF band and a radiating element 22 operating for example in an HF band of
higher frequencies. In particular, the low frequency band can cover frequencies varying
from 698 MHz to 960 MHz (in particular the GSM system) and in particular the high
frequency band can cover frequencies from 1710 MHz to 2700 MHz (particularly DCS,
UMTS and LTE systems)
The LF radiating element 2 1 comprises four radiating strands 23, 24, 25, 26,
belonging to four dipoles 27, 28, 29, 30, that are arranged so as to form a square around
the HF radiating element 22. The radiating strands 23, 24, 25, 26 of the LF radiating
element 2 1 are arranged in a plane 33 parallel to the antenna reflector 34. The geometry
of the LF radiating element 2 1 limits the impact of its presence on the performances of the
HF radiating element 22 located inside the square formed by its arms 23, 24, 25, 26. The
width of the LF radiating element 2 1 is chosen to be equal to the distance separating two
HF radiating elements 22. Consequently, all transverse strands 23, 25, that are practically
perpendicular to the longitudinal X axis of the multiband antenna, are located
symmetrically at mid-distance between two adjacent HF radiating elements 22. The
vertical power supply lines of the dipoles are then arranged at equal distance from the two
adjacent HF radiating elements 22 and thus all elements 22 are affected in the same way.
The HF radiating element 22 comprises two dipoles 3 1 and 32, associated
orthogonally in a dual cross polarisation arrangement and each comprising two
arms 31a, 31b and 32a, 32b one prolonging the other, arranged in a plane 35 parallel to
the antenna reflector 34.
The plane 33 of the radiating strands 23, 24, 25, 26 of the LF element 2 1 is
placed above the plane 35 of arms 31a, 31b and 32a, 32b of the HF element 22. The
radiating strands 23, 24, 25, 26 of dipoles 27, 28, 29, 30 of the LF radiating element 2 1
and the arms 31a, 31b and 32a, 32b of the dipoles 3 1 and 32 of the HF radiating
element 22 are placed above the same reflector 34 that acts as their common ground
plane.
A variant embodiment of a radiating device 40 is shown in figures 3 and 4 . The
two-frequency band radiating device 40 comprises a radiating element 4 1 operating for
example in an LF low frequency band and a radiating element 41' operating for example
in an HF band with higher frequencies. The LF radiating element 4 1 comprises four
radiating strands 42, 43, 44, 45 belonging to the four dipoles 46, 47, 48, 49.
Each of the dipoles 46, 47, 48, 49 is provided with a microstrip type power supply
system. Each power supply system comprises a power supply line 50, 51, 52, 53
adjacent to a ground plane composed of the stand 54, 55, 56, 57 of the
dipole 46, 47, 48, 49 contiguous with the powered dipole. The power supply
line 50, 51, 52, 53 thus forms a vertical connection between one of the ends of a
corresponding radiating strand 42, 43, 44, 45 of the LF radiating element 4 1 and the
coaxial cable that powers it.
As shown in detail in figure 4 , each prolongation 43a, 43b of the conducting part
forming the radiating strand 43 is folded at 90°. One of the prolongations 43a forms the
stand 55 of the dipole 47 and the other prolongation 43b forms the power supply line 50 of
the dipole 46. Similarly, one of the folded prolongations 44b of the part forming the
radiating strand 44 forms the power supply line 5 1 of the dipole 47, and one of the folded
prolongations 42a of the radiating strand 42 forms the stand 54 of the dipole 46.
Thus, the stand 54, 55, 56, 57 belonging to one of the dipoles 46, 47, 48, 49 acts
as the ground plane for the power supply line 50, 51, 52, 53 that is contiguous with it.
Consequently, the dipoles 46, 47, 48, 49 are asymmetric. This solution can reduce the
number of parts necessary to make the radiating element 4 1 from eight parts for known
devices (4 dipoles with their 4 power supply lines) to four parts for the radiating
element 4 1 according to this embodiment (4 dipoles in which the power supply is
integrated) and consequently simplifies assembly of the radiating element 41. The
verticality of the power supply lines 48, 49, 50, 5 1 also contributes to preventing
interactions between the radiating element 4 1 operating in the LF band and adjacent
radiating elements 41' operating in the HF band.
Figure 5 shows an antenna 60 operating in wide band (700MHz-960MHz)
comprising radiating elements 6 1 operating in the LF band, similar to what is shown in
figure 1, and radiating elements 62 operating in the HF band arranged on a common
reflector 63. An HF radiating element 62 comprises two coplanar dipoles 64, 65
associated orthogonally in a dual cross polarisation arrangement and a directional
element 66 that is not interconnected to the dipoles 64, 65 and that is arranged above the
dipoles 64, 65. The radiating elements 6 1 are arranged such that their transverse
strands 67 are located between two HF radiating elements 62.
Reflecting longitudinal partitions 68 may be located on the reflector 62 on each
side of the alignment of the HF radiating elements 64, so as to optimise the radiation
diagram in the horizontal plane of the antenna 60. These partitions may have different
dimensions and different shapes, for example like the partition 36 shown in figure 2 .
The combined use of a radiation element like that described above operating on
a low frequency band with a radiating element operating on a high frequency band gives
an antenna operating on a wide band that is narrower than known antennas.
Alternately, cubic or cuboid cavities of different sizes could be used instead of the
partitions, as shown in figure 6 . An LF element 70, similar to that shown in figure 1, is
placed on an antenna reflector 7 1. An HF element 72 is placed at the centre of the
square formed by the radiating strands of the LF element 70 to form a radiating device 73.
The HF element 72 is surrounded by a cubic cavity 74. An HF element 75 located close
to the radiating device 73 is also surrounded by a cubic cavity 76 that is less tall.
Obviously, this invention is not limited to the embodiments described but it can be
used in many variants that could be developed by those skilled in the art without going
outside the scope of this invention. Although the invention is described for a radiating
element operating particularly in the LF band in a two-frequency band application, the
radiating element can be used regardless of the frequency necessary for the final
application. This radiating element could also be used in a single frequency wide band
antenna or in three-frequency band or multiband antenna.
Although embodiments have been described with reference to a number of
illustrative embodiments thereof, it should be understood that numerous other
modifications and embodiments can be devised by those skilled in the art that will fall
within the spirit and scope of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts and/or arrangements of
the subject combination arrangement within the scope of the disclosure, the drawings and
the appended claims. In addition to variations and modifications in the component parts
and/or arrangements, alternative uses will also be apparent to those skilled in the art.
CLAIMS
1. Dual polarised radiating element comprising four dipoles each comprising
one stand and two arms, a first arm and a second arm belonging to two adjacent dipoles
form a straight radiating strand composed of a single part, and the four radiating strands
are arranged so as to form a square that is disjoint at the corners.
2 . Radiating element according to claim 1, in which each of the radiating
strands is composed of a single conducting part with folded prolongations at each end of
the radiating strand.
3 . Radiating element according to claim 2 , in which the prolongations of each
conducting part are folded at 90° from the plane of the radiating strands.
4 . Radiating element according to one of claims 2 and 3 , in which at least one
of the prolongations of each part forms a half-stand of the stand of one of the dipoles.
5 . Radiating element according to one of claims 1 to 4 , in which each dipole is
powered by a power supply system comprising a power supply line and at least one
ground plane that is one of the half-stands of the stand of one of the dipoles.
6 . Radiating element according to claim 5 , in which the power supply system
for a dipole has a stripline structure formed from a power supply line surrounded by two
ground planes, each ground plane being one of the half-stands of the stand of one of the
dipoles.
7 . Radiating element according to claim 5 , in which the power supply system
for a dipole has a microstrip structure formed from a power supply line adjacent to a
ground plane that is the stand of the contiguous dipole.
8 . Radiating device comprising a first radiating element operating in a first
frequency band according to one of the previous claims, and at least one second radiating
element operating in a second frequency band and comprising at least one dipole,
arranged at the centre of the square formed by the radiating strands of the first radiating
element, the radiating elements being arranged above a common reflector.
9 . Antenna comprising at least one first radiating element operating in a first
frequency band according to one of claims 1 to 7 , and at least one second radiating
element operating in a second frequency band, the first and second radiating elements
being aligned and arranged above a common reflector such that the transverse strands of
the first radiating elements are located between two adjacent second radiating elements.
10. Antenna according to claim 9 , in which partitions are arranged parallel to
the alignment of the second radiating elements, inside the alignment of the first radiating
elements.
11. Antenna according to claim 9 , in which parallelepiped, cubic or rectangular
shaped cavities are arranged around the second radiating elements, inside the alignment
of the first radiating elements.
AMENDED CLAIMS
received by the International Bureau on 12 March 2012 (12.03.2012)
1. Dual polarised radiating element comprising four dipoles each comprising
one stand and two orthogonal arms, wherein a first arm and a second arm belonging to
two adjacent dipoles and being colinear form a straight radiating strand composed of a
single part, and the four radiating strands are arranged so as to form a square that is
disjoint at the corners.
2. Radiating element according to claim 1, wherein the radiating strand is
composed of a single conducting part and the end of the conducting part is folded so as
to form folded prolongation at the end of the radiating strand.
3. Radiating element according to claim 2, wherein the end of the conducting
part forming folded prolongation is folded at 90° from the plane of the radiating strands.
4. Radiating element according to one of claims 2 and 3, wherein the stand
comprising two half-stands, the prolongation of the conducting part forms the half-stand
of the stand of one of the dipoles involved in the radiating strand.
5. Radiating element according to one of claims 1 to 4, wherein the dipole is
powered by a power supply system comprising a power supply line and at least one
ground plane that is the half-stand of the stand of the dipole.
6. Radiating element according to claim 5, wherein the power supply system
for a dipole has a stripline structure formed from a power supply line surrounded by two
ground planes, each ground plane being one of the half-stands of the stand of the dipole.
7. Radiating element according to claim 5, wherein the power supply system
for a dipole has a microstrip structure formed from a power supply line adjacent to a
ground plane that is the stand of the dipole.
8. Radiating device comprising a first radiating element operating in a first
frequency band according to one of the previous claims, and at least one second
radiating element operating in a second frequency band and comprising at least one
dipole, arranged at the centre of the square formed by the radiating strands of the first
radiating element, the radiating elements being arranged above a common reflector.
9. Antenna comprising at least one first radiating element operating in a first
frequency band according to one of claims 1 to 7, and at least one second radiating
element operating in a second frequency band, the first and second radiating elements
being aligned and arranged above a common reflector such that the transverse strands
of the first radiating elements are located between two adjacent second radiating
elements.
10. Antenna according to claim 9, wherein partitions are arranged parallel to
the alignment of the second radiating elements, inside the alignment of the first radiating
elements.
1. Antenna according to claim 9, in which parallelepiped, cubic or rectangular
shaped cavities are arranged around the second radiating elements, inside the alignment
of the first radiating elements.