Note: Descriptions are shown in the official language in which they were submitted.
CA 02719300 2010-09-22
PCT/EP2009/002234
345 P 503 PCT
Multilayer antenna having a planar design
The invention relates to a multilayer antenna having a
planar design as claimed in the pre-characterizing clause
of claim 1.
A generic multilayer antenna has become known from DE 10
2006 027 694 B3.
The multilayer antenna having a planar design comprises in
this case an electrically conductive earth surface, a
conductive radiation surface (which is arranged with
parallel spacing from the earth surface) and also a
dielectric carrier which is sandwiched between the earth
surface and the radiation surface. A support means, on
which an electrically conductive patch element is
positioned, is arranged above the radiation surface. The
support means for the patch element has a thickness or
height which is less than the thickness or height of the
patch element.
The patch element itself can be configured as a volume
body, i.e. as solid material. It is also possible for the
patch element to consist of a metal plate or a metal sheet
which is provided, for example by cutting or punching,
with peripheral webs, edges or the like extending away
from the dielectric carrier.
An antenna of this type is particularly suitable as a
motor vehicle antenna, including for example for SDARS
services. For this purpose, a patch antenna of this type
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can be provided in addition to further antenna radiators
for other services on a common base assembly on antenna
structures which are separate from the base assembly and
generally protrude vertically upward.
An overall antenna assembly of this type is then located
below a hood, such as is known for example from EP 1 616
367 B1.
In antenna assemblies of this type, for example using a
patch antenna known from DE 10 2006 027 694 B3, which was
mentioned at the outset, care must be taken to ensure that
certain tolerances are adhered to. This certainly requires
the availability of an additional small dimension of from
1 - 2 mm as tolerance compensation to avoid insufficient
internal space within a hood. However, in hood-shaped
covers, overall this certainly leads to a perceptible
increase in the size of the hood as a whole, as even a
small increase in the minimum height leads overall, owing
to a specific curved configuration of the hood, to an
undesirable widening and lengthening of the hood housing.
A compact broadband antenna has, in addition, become known
from EP 1 793 451 Al. According to Figures 4 and 5 of this
prior publication, the patch antenna arrangement comprises
an earth surface and an active, planiform patch antenna
arranged above the earth surface and separated from it by
a dielectric substrate, above which at a distance a plane,
parasitic patch antenna is arranged. This plane, parasitic
patch antenna is fastened to the underside or inside of a
radome which comprises the dielectric substrate above the
earth surface together with the outer conversion range.
H-shaped patch antenna arrangements have become known from
the prior publication Anguera, J.; Boada, L.; Puente, C.;
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Borja, C.; Soler, J.: "Stacked H-shaped microstrip patch
antenna", IEEE Transactions on Antennas and Propagation,
Vol. 52, No. 4, 983-993, April 2004, and also from the
prior publication Moussa, I.K.; Mohamed, D.A.E.; Badran,
I.: Analysis of Stacked Rectangular Microstrip Antenna",
National Radio Science Conference, 2007.1-11, 13-15 March
2007. The effect of variable distances between patch
elements and the radiation surface can also be inferred
from the last-mentioned publication.
A microstrip antenna array has also become known from EP 0
279 050 Al. It comprises an active patch antenna element,
above which at a distance, by interconnecting a
dielectric, a first, plate-type, parasitic element and
above that at a further distance a second, plate-type,
parasitic element are arranged. In this way, a broadband
antenna arrangement can be achieved.
The object of the present invention is, however, to
develop a further improved multilayer antenna having a
planar design that allows a reduction in the tolerances to
be adhered to even in the case of optimum antenna
reception.
According to the invention, the object is achieved in
accordance with the features disclosed in claim 1.
Advantageous embodiments of the invention are disclosed in
the sub-claims.
The multilayer antenna having a planar design corresponds
basically to the construction known from DE 10 2006 027
694 B3. In this respect, reference is made to the
disclosure of the above-mentioned prior publication and to
the content of the present application.
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The improvement may now be achieved as a result of the
fact that the parasitic patch, which is provided on the
planar patch antenna above the support means 19, is now
divided at least into two and comprises a first patch
element and also a patch additional element. In order to
allow a different overall height, the two patch elements
can interlock telescopically to differing degrees; that is
to say, that the one patch element can dip into the other
patch element to differing degrees. One patch element may
in this case preferably be configured in a box-shaped or
box-like manner, preferably with a peripheral and upwardly
open edge. The second patch element, which will be
referred to hereinafter in some cases also as the patch
additional element, may consist of or comprise a volume
body or, for example, a likewise box-shaped radiation
element, thus allowing both patch elements to be moved
toward one another in a differing position in which one
patch element, as it were, ' ' dips '' in the other by a
certain height. In other words, preferably at least one of
the two patch elements should therefore have a length
and/or a width which is preferably at least slightly less
than the internal dimension of the second patch element
which is provided with a peripheral or generally
peripherally closed edge [and can] if required dip therein
to a certain degree. In this case, the further patch
additional element pertaining to the parasitic radiator
arrangement can, as mentioned, be provided as a volume
body or else as a box-shaped element which is preferably
downwardly open. However, in this case, the lower patch
element can in particular also be equipped as a volume
body or as a box-shaped patch element which is, for
example, even downwardly open and can dip into the upper
patch additional element, especially if it is configured
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to be slightly smaller (i.e. in the longitudinal and
transverse directions) than the upper patch additional
element.
This patch additional means is now fastened to the inside
5 of the hood, which overlaps the entire antenna assembly,
and/or is held thereby, in such a way that this patch
additional means rests directly above the patch assembly
which is located on the support means. Viewed from the
side, there should in this case preferably be no interval
between the edges or webs of the patch assembly, which is
located on the support means, and the patch additional
means located thereabove. However, in the event of
differences in tolerance, it is then quite possible for
the upper patch additional means to dip to differing
degrees into the box-shaped patch element located on the
carrier means, or else a gap is formed between the two.
In principle, the assembly can also be inverted in such a
way that, for example, the patch element which is fastened
to the hood is made larger and provided with the
aforementioned generally closed peripheral edge or web and
in this case, if required, overlaps to differing degrees
as required the patch element which is located therebelow
and held by way of the actual patch antenna.
Overall, this assembly according to the invention allows
the height of the hood to be reduced, as no additional
(albeit only slight) height dimension must be provided for
differences in tolerance. If there are differences in
tolerance, this merely means that the patch element, which
is held on the inside of the hood, can reach to differing
degrees into the box-shaped patch assembly which is
located therebelow and rests on the support means.
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However, from the point of view of electrics, this split
patch functions like the one-piece patch element described
in the generic prior art according to DE 10 2006 027 694
B3.
Further advantages, details and features of the invention
will emerge from the following discussion of the
invention. In the individual drawings:
Figure 1 is a cross section through a multilayer antenna
according to the invention, in particular a patch antenna
comprising a patch additional element which is
additionally provided in accordance with the invention;
Figure 2 is a schematic plan view onto the exemplary
embodiment according to Figure 1;
Figure 3 is a schematic three-dimensional view of the
patch antenna according to the invention with a primary
patch element which is configured in the manner of an open
box and into which a patch additional element dips;
Figure 4 is a view corresponding to Figure 3, although
without the further patch additional element;
Figure 5 is a schematic cross section through the
exemplary embodiment represented in Figure 3 with a hood
covering the entire assembly;
Figure 6 is a cross section differing from Figure 5 with a
differing hood geometry and a different type of holding
means for the patch additional element;
Figure 7 is a schematic plan view of a modified exemplary
embodiment from Figure 2; and
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Figure 8 is an exemplary embodiment differing from Figure
3 with a patch additional element which, at the top, has a
recess in the central surface.
Reference will now firstly be made to the exemplary
embodiment according to Figures 1 to 4 showing a patch
antenna which has surfaces and layers arranged one above
another along an axial axis Z. In principle, a patch
element of this type is known from DE 10 2006 027 694 B3,
to the full disclosure of which reference is made.
Nevertheless, the patch element known from DE 10 2006 027
694 does not have a split parasitic patch assembly
comprising a patch additional element according to the
invention.
The schematic cross section according to Figure 1 shows
that the patch antenna A has on what is known as its
underside or mounting side 1 an electrically conductive
earth surface 3. Arranged on the surface 3 or laterally
offset therefrom is a dielectric carrier 5 which, in plan
view, conventionally has an outer contour 5' corresponding
to the outer contour 3' of the earth surface 3. This
dielectric carrier 5 can however also be larger or smaller
and/or provided with an outer contour 5' differing from
the outer contour 3' of the earth surface 3. In general,
the outer contour 3' of the earth surface can be n-
polygonal and/or even provided with curved portions or be
curved in its configuration, although this is
unconventional.
The dielectric carrier 5 comprising an upper side 5a and a
lower side 5b has a sufficient height or thickness which
generally corresponds to a multiple of the thickness of
the earth surface 3, i.e. in contrast to the earth surface
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3, which roughly consists merely of a two-dimensional
surface, the dielectric carrier 5 is configured as a
three-dimensional body having sufficient height and
thickness.
As an alternative to the dielectric body 5, a different
type of dielectric or a different type of dielectric
construction can also be provided, for example using air
or with a layer of air next to a further dielectric body.
If air is used as the dielectric, then obviously a
corresponding carrier means, comprising for example
stilts, bolts, columns, etc., must then obviously be
provided to carry and to hold the further parts of the
patch antenna which are located thereabove and will be
described hereinafter.
An electrically conductive radiation surface 7, which can
likewise again roughly be conceived of as a two-
dimensional surface, is configured on the upper side 5a
opposing the underside 5b (which comes to lie adjacent to
the earth surface 3). This radiation surface 7 is
electrically powered and excited via a feed line 9 which
extends preferably in the transverse direction, in
particular perpendicularly to the radiation surface 7 from
below through the dielectric carrier 5 in a corresponding
hole or a corresponding channel 5c.
From a connection point 11 which is generally located at
the bottom and to which a coaxial cable (not shown in
greater detail) can be connected, the inner conductor of
the coaxial cable (not shown) is then electrically
connected to the feed line 9 and thus to the radiation
surface 7. The outer conductor of the coaxial cable (not
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shown) is then electrically connected to the earth surface
3 which is located at the bottom.
The exemplary embodiment according to Figure 1 ff. shows a
patch antenna having a dielectric 5 and a square shape
viewed from above. This shape or the corresponding contour
or outline 5' can however also differ from the square
shape and generally have an n-polygonal shape. Although
unconventional, even curved outer delimitations may be
provided.
The radiation surface 7 resting on the dielectric 5 can
have the same contour or outline 7' as the dielectric 5
located therebelow. In the exemplary embodiment shown, the
basic shape is likewise formed so as to be square, in
adaptation to the outline 5' of the dielectric 5, although
it has at two opposing ends flattenings 7'' formed, as it
were, as a result of the omission of an isosceles-
rectangular triangle. Generally, the outline 7' may
therefore also be an n-polygonal outline or contour or
even be provided with a curved outer delimitation 7'.
The aforementioned earth surface 3, although also the
radiation surface 7, is sometimes referred to as a ''two-
dimensional'' surface, as its thickness is so low that it
is scarcely possible to describe it as a ' 'volume body' ' .
The thickness of the earth surface and the radiation
surface 3, 7 is conventionally less than 1 mm, i.e.
generally less than 0.5 mm, in particular less than 0.25
mm, 0.20 mm, 0.10 mm.
The patch antenna A described hereinbefore can, for
example, consist of a conventional commercial patch
antenna, preferably of what is known as a ceramic patch
antenna in which, that is to say, the dielectric carrier
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layer 5 is made of a ceramic material. As will become
apparent from the remainder of the description, there may
also be configured, beyond the patch antenna A described
hereinbefore, a patch antenna in the sense of a stacked
5 patch antenna in which there is additionally provided,
with lateral of vertical offset from the upper radiation
surface 7, a patch assembly 13 comprising a first primary
patch element 53 and a second secondary patch additional
element 55. In this case, the first parasitic patch
10 element 53 is configured in such a way that it has,
compared to the aforementioned earth surface 3 and the
radiation surface 7, a three-dimensional structure with a
differing, i.e. greater, height or thickness.
Preferably, use is made of a support means 19 having a
thickness or height 17, in particular a dielectric support
means 19, via which the primary patch element 53 is held
and supported. This dielectric support means 19 consists
preferably of an adhesion or mounting layer 19' (Figure 6)
which can be configured, for example, as what is known as
a double-sided adhesive adhesion and mounting layer 19'.
For this purpose, use may be made of conventional
commercial double-sided adhesive tapes or double-sided
adhesive foam strips, adhesive pads or the like having an
appropriate, above-mentioned thickness. This easily allows
the aforementioned patch element 53 to be fastened and
mounted on the upper side of a conventional commercial
patch antenna, in particular a conventional commercial
ceramic patch antenna.
The stacked patch antenna as described is positioned on a
chassis B which in Figure 1 is indicated merely as a line
and may, for example, be the base chassis for a motor
vehicle antenna in which the antenna according to the
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invention may if appropriate be integrated in addition to
further antennas for other services. The stacked patch
antenna according to the invention can for example be
used, in particular, as an antenna for geostationary
positioning and/or for the reception of satellite or
terrestrial signals, for example of what is known as the
SDARS service. There are, however, no restrictions
preventing use for other services also.
The primary patch element 53 can, for example, consist of
an electrically conductive, upwardly open, box-shaped
metal body having appropriate longitudinal and transverse
extensions and sufficient height.
As may be seen from the three-dimensional view according
to Figures 3 and 4, this patch element 53 can have a
rectangular or square structure with a corresponding
outline 53'.
In the exemplary embodiment shown, the patch element 53
has a longitudinal extension and a transverse extension
which, on the one hand, are greater than the longitudinal
and transverse extensions of the radiation surface 7
and/or, on the other hand, are also greater than the
longitudinal and transverse extensions of the dielectric
carrier 5 and/or of the earth surface 3 located
therebelow.
As may be seen from the figures, the parasitic patch
assembly 13 is divided into two and comprises the primary
patch element 53 which rests on the carrier means 19 or is
fastened and held thereon and is configured in the manner
of an upwardly open box and comprises a base surface or
central surface 153 which, in the exemplary embodiment
shown, is provided with a peripheral edge or a peripheral
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web 53b (that is to say, generally a corresponding
elevation 53b) which rises transversely, in particular
perpendicularly, from the plane of the base surface 153
which is also parallel to the earth surface. A patch
element 53 of this type can, for example, be produced by
cutting and tilting from an electrically conductive metal
sheet, wherein the peripheral webs 53b can be electrically
connected to one another in the corner regions, for
example by soldering (wherein recesses may furthermore
also be provided in the central region 153, as will be
examined in greater detail hereinafter).
The secondary patch additional element 55, which in the
exemplary embodiment shown is likewise box-shaped, in the
manner of a volume body having a corresponding length and
width and height, is then located above this primary patch
element 53. The configuration of the length and width is
such that the dimensions are, for example, at least
slightly smaller than the free inner length and transverse
length between the peripheral webs 53b of the primary
patch element 53. That is to say, this allows the
secondary patch element, i.e. the secondary patch
additional element 55, to dip to differing degrees into
the interior 53a of the lower patch element 53. In other
words, the lowest level, i.e. the bottom delimiting plane
55' comes to lie in the interior 53a of the primary patch
element 53, i.e. below the upper delimiting plane 53'
which is defined by the upper peripheral rim of the webs
or edges or outer walls 53b.
However, as an alternative to a volume body formed in this
way, the secondary patch additional element 55 can also be
configured in such a way that it is formed, like the lower
patch element 53, in the manner of an open box with an
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interior or receiving chamber 55a (see Figures 5 and 6)
and with a peripheral edge or a peripheral web 55b
(generally a peripheral elevation 55b), i.e. this
secondary patch additional element 55 points downward with
its opening side and is closed off by the upper base 155.
The patch additional element 55 thus described is now held
by a separate support means 61, preferably in the form of
a hood or housing 61' covering and receiving the antenna.
Figure 5 is in this case a perpendicular section of a
first schematic exemplary embodiment transversely to the
earth plane or transversely to the radiation planes of the
patch antenna in which the secondary patch additional
element 55 is held and fastened with its upper side 13a,
which is formed by the base surface or central surface
155, on the top hood upper side 61a, which in this
exemplary embodiment is flat in its configuration, on the
inside 61b located there, for example by adhesion, by a
separate locking or fixing mechanism, etc.
This embodiment allows tolerance errors easily to be
compensated for as a result of the fact that this patch
additional element 55 can dip into the lower primary patch
element 53 to differing degrees depending on the resulting
overall construction of the patch antenna, including the
primary patch element 53 and the patch additional element
55, and also depending on the height of the hood 61 and
the available internal dimension below this hood 61. This
allows tolerance errors to be compensated for.
The variation according to Figure 6 shows a differently
configured hood which is more trapezoidal in cross
section. In this case, the upper patch additional element
55 is suspended from the upper side 61a of the hood via a
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separate support means 63. Any desired mechanical holding
and/or locking and/or clamping mechanisms may in this case
be used to support and fix the upper patch additional
element accordingly.
It may therefore be seen from the illustrated construction
that it is entirely possible for the overall height 114 of
the patch assembly 13 to vary in accordance with the
differing tolerance conditions. This is achieved as a
result of the fact that the patch assembly 13 is divided
at least into two and comprises the two components which
may if appropriate be positioned at differing relative
distance from one another, namely the patch element 53 and
the patch additional element 55.
The thickness of the patch assembly 13 as a whole should
preferably have a dimension which is not just twice, 3, 4
or 5 times, etc. but rather above all 10 times, 20, 30,
40, 50, 60, 70, 80, 90 and/or 100 and more times the
thickness of the earth surface 3 and/or the thickness of
the radiation surface 7.
In the exemplary embodiment shown, the thickness or height
114 of the patch assembly 13 as a whole is equal to or
greater than a distance 17 between the underside of the
patch element 53 and the upper side of the radiation
surface 7. On the other hand, this distance should also be
not less than 0.5 mm, preferably greater than 0.6 mm, 0.7
mm, 0.8 mm, 0.9 mm or equal to or greater than 1 mm.
Values of about 1 . 5 mm, i . e . generally between 1 mm and 2
mm or 1 mm and 3 mm, 4 mm or up to 5 mm are entirely
sufficient.
Furthermore, it may also be seen that the height or
thickness 114 of the three-dimensional patch assembly 13
CA 02719300 2010-09-22
is preferably less than the height or thickness 15 of the
dielectric carrier 5. Preferably, the overall thickness or
overall height 114 of the patch assembly 13 has a
dimension corresponding to less than 90 %, in particular
5 less than 80 %, 70 %, 60 %, 50 % or even less than 40 %
and if appropriate 30 % or less than 20 % of the height or
thickness 15 of the carrier element 5.
In addition, no limitation need necessarily be placed on
the above-mentioned height. Therefore, the height or
10 thickness 114 of the three-dimensional patch assembly 13
can also have a greater, and above all much greater,
height or thickness than the thickness or height 15 of the
dielectric carrier 5. In other words, this height or
thickness 15 of the carrier element 5 may, for example,
15 also have a dimension corresponding to up to 1.5 times, 2
times, 4, 5, 6, 7, 8, 9 and/or 10 and more times the
height or thickness 15 of the carrier element 5.
On the other hand, the thickness or height 114 of the
patch assembly 13 as a whole should preferably be greater
than the distance dimension 17 between the radiation
surface 7 and the underside 13b of the patch element 13.
The height 114a of the lower patch element 53 and the
height 114b of the upper patch additional element 55 are
preferably the same so as to allow maximum tolerance
compensation. Preferably, at least the two individual
heights 114a and 114b (Figure 5) with respect to the patch
element 53 should differ from one another relative to the
patch additional element 55 by less than 50 %, in
particular less than 40 %, 30 %, 20 %, in particular less
than 10 %.
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Obviously, the upper patch additional element 55 is also
electrically conductive or provided on its outside or if
appropriate with a cavity body having a conductive inside.
Therefore, this body may likewise consist of metal or of a
plastics material or a dielectric body which is coated if
appropriate with an electrically conductive layer. In
practice, use may in this case be made of an installation
within a hood in which the upper second patch element 55
optionally comes to lie with its lower delimiting plane
55' only at the level of the upper delimiting plane 53' of
the lower patch element 53, or even is positioned slightly
thereabove.
Merely for the sake of completeness, it should also be
noted that the overall construction of the lower and upper
patch elements may also be inverted in such a way that,
for example, the upper patch element 55, the outer
contours of which are smaller, is constructed on the
carrier means 19 and the patch element 53, which is shown
at the bottom in the figures, is fastened and/or held to a
hood; that is to say, in other words, the patch element
which is then on top overlaps the lower patch element, and
the lower patch element can dip in the upper patch
element. However, this would lead to an increase in the
size of the dimensions of the hood, and this is in
principle less desirable.
In principle, it should also be noted that one respective
part of the patch assembly 13 as a whole, which part is
smaller and can dip into the other respective patch
element or patch additional element (which is configured
in the manner of an open box), may be configured as a
volume body (i.e. a solid body) or likewise as a box which
is open toward one side. In this case, the open side of
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the box-shaped patch element 53 or patch additional
element 55 thus configured lies preferably in each case on
the side facing the other patch element. In other words,
the open sides of the patch element 53 and of the patch
additional element 55 therefore lie on the two mutually
facing sides. In principle, the opening side may, in
particular in the case of the smaller patch additional
element 55, also be configured on the side which is remote
from the patch element 53.
In conclusion, it will be noted merely in principle with
reference to Figure 7 that other geometric shapes and
contours are conceivable not only for the upper radiation
surface 7 but rather preferably also for the two mutually
engageable patch means 53, 55.
In the exemplary embodiment according to Figure 7, at
least at two opposing regions, both the patch element 53
and the patch additional element 55 are provided with a
shape which differs from a rectangular or square
structure, in which flattenings 153' and 155' respectively
are in this case provided at the corner regions.
Nevertheless, generally speaking, the shapes of the
outlines of both patch elements 53, 55 should be adapted
to one another in such a way that they are in general at
least similar to one another and allow optimum, as it were
telescopic, engageability.
Described hereinbefore are exemplary embodiments in which,
as has been shown in the drawings, the patch element 53
and the patch additional element 55 dip at least partly
one inside the other. As mentioned hereinbefore, the two
patch elements 53, 55 can also be arranged in such a way
that the lower delimiting plane of the upper patch element
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and the upper delimiting plane of the lower patch element
lie precisely in one plane or even in such a way that a
distance is formed between these two delimiting planes.
The arrangement should in this case be such that the
maximum distance between the upper delimiting plane 53' of
the primary patch element 53 and the lower delimiting
plane 55' of the patch additional element 55 is less than
5 times the height 114b of the patch additional element
55, preferably is less than 4 times, 3 times, 2 times and
in particular 1 times the height 114b of the patch
additional element 55 or even is less than half the height
114b.
Finally, it should also be noted, with regard to the
exemplary embodiment according to Figure 8 which shows,
merely for the sake of completeness, possible
modifications, that a recess or a cutout 5511 may, for
example, be formed also in the upper base surface or
central surface 155 of the patch additional element 55. In
the exemplary embodiment shown, this recess 5511 is
configured in the form of a round hole or circle.
