Title of Invention	" IMPROVEMENT TO SOURCE-ANTENNAS FOR TRANSMITTING /RECEIVING ELECTROMAGNETIC WAVES OPERATING IN THREE FREQUENCY BANDS FOR SATELLITE TELECOMMUNICATIONS SYSTEMS"
Abstract	The present invention relates to a source antenna for transmitting/receiving electromagnetic waves comprising means (11) for transmitting electromagnetic waves with longitudinal radiation operating in a first frequency band and means for receiving electromagnetic waves, characterized in that the means for receiving electromagnetic waves consist of a first array (231 – 234) of n radiating elements operating in a second frequency band and a second array (321 – 324 – 341 – 344) of n' radiating elements operating in a third frequency band, the first and second arrays and the longitudinal-radiation means having a substantially common phase centre and the radiating elements of the first and second arrays being arranged around the longitudinal-radiation means. (FIG.)2

Title of Invention

" IMPROVEMENT TO SOURCE-ANTENNAS FOR TRANSMITTING /RECEIVING ELECTROMAGNETIC WAVES OPERATING IN THREE FREQUENCY BANDS FOR SATELLITE TELECOMMUNICATIONS SYSTEMS"

Abstract

The present invention relates to a source antenna for transmitting/receiving electromagnetic waves comprising means (11) for transmitting electromagnetic waves with longitudinal radiation operating in a first frequency band and means for receiving electromagnetic waves, characterized in that the means for receiving electromagnetic waves consist of a first array (231 – 234) of n radiating elements operating in a second frequency band and a second array (321 – 324 – 341 – 344) of n' radiating elements operating in a third frequency band, the first and second arrays and the longitudinal-radiation means having a substantially common phase centre and the radiating elements of the first and second arrays being arranged around the longitudinal-radiation means. (FIG.)2

Full Text	The present invention relates to a source- antenna for transmitting/receiving electromagnetic waves, more particularly a system of source-antennas allowing the reception of satellite television signals in a certain frequency band such as the Ku band lying between 10.7 and 12.75 GHz and of satellite communications in a second frequency band such as the Ka band at around 30 GHz in transmission and at around 20 GHz in reception, using just a single structure of antennas. There are at present source-antenna structures for transmitting/receiving electromagnetic waves which operate with two frequency bands. These source-antennas make it possible to meet the requirements of satellite communication systems in respect of high bit rate multimedia applications. An antenna of this type has been proposed in patent WO 99/357/1 in the name of THOMSON multimedia. These dual-band antenna structures are composed of two cofocused antennas. Thus, as described in the abovementioned patent application, the first antenna used for reception or downpath consists of an array of n patches. This array can be used in linear or circular polarization and benefit from two orthogonal polarizations. The second antenna used for transmission or uppath consists of a waveguide terminating in a dielectric rod commonly referred to as a "polyrod". This antenna can be used in linear or circular polarization and benefit from two orthogonal polarizations. These two antennas are made in such a way that the phase centres of the "polyrod" and of the array of patches practically coincide and can be placed at the focus of the system of antennas. The aim of the present invention is to incorporate into a transmission/reception source- antenna structure operating in two frequency bands another source-antenna structure which operates in respect of reception, namely the downpath, at a lower working frequency than the other two frequencies, more particularly in a frequency band allowing the reception of conventional satellite television signals. This makes it possible to obtain an antenna structure operating on three frequency bands. Thus, the subject of the present invention is a source antenna for transmitting/receiving electromagnetic waves comprising means for transmitting electromagnetic waves with longitudinal radiation operating in a first frequency band and means for receiving electromagnetic waves, characterized in that the means for receiving electromagnetic waves consist of a first array of n radiating elements operating in a second frequency band and a second array of n" radiating elements operating in a third frequency band, the first and second arrays and the longitudinal- radiation means having a substantially common phase centre and the radiating elements of the first and second arrays being arranged around the longitudinal- radiation means. According to one embodiment, the first array of n radiating elements consists of an array of n patches having linear or circular, orthogonal double polarization, the first array of n patches being connected to a feed circuit made in microstrip technology on a first substrate. Moreover, the means for transmitting electromagnetic waves with longitudinal radiation consist of an antenna of the longitudinal-radiation travelling wave type with axis coinciding with the axis of radiation, excited by means comprising a waveguide, the waveguide being filled with a dielectric material. This makes it possible to restrict the dimensions of the cross section of the waveguide and to reduce the guided wavelength inside the guide. Moreover, the antenna of the travelling wave type may consist of a dielectric rod known as a "polyrod" or of a helix. Furthermore, the second array of n" radiating elements consists of an array of n" radiating elements having linear or circular, orthogonal double polarization and a wide band. This array is made, preferably, by using two parallel substrates, one of the substrates being the first substrate receiving the first array. According to a first embodiment, the substrate is covered with a metallic layer forming an earth plane comprising demetallized zones, at the level of the radiating elements of the second array. According to a preferred embodiment, the radiating elements of the array with orthogonal double polarization and a wide band consist of two patches which are superimposed and made respectively on each substrate and coupled electromagnetically. In this case, the two substrates may be connected plumb with the demetallized zones by metallic walls. According to another embodiment, the radiating elements of the array with orthogonal double polarization and with a wide band consist of a patch coupled electromagnetically to a probe connected to the feed circuit. According to yet another embodiment, the radiating elements of the array with orthogonal double polarization and a wide band consist of an aperture made in the first substrate and a probe connected to the feed circuit and made on the parallel substrate. According to yet another embodiment, the radiating elements of the array with orthogonal double polarization and a wide band consist of an aperture made in the first substrate and a patch connected to the feed circuit and made on the parallel substrate. Moreover, the second array of n" radiating elements is connected to a feed circuit made in microstrip technology. According to a characteristic of the present invention, the first array of n radiating elements is an array with four elements arranged in a square and the second array of n" radiating elements is an array with four elements arranged in a cross around the first array. In accordance with the present invention, the first and second frequency bands correspond to the Ka band and the third frequency band corresponds to the Ku band. Other characteristics and advantages of the present invention will become apparent on reading the following description, this description being given with reference to the herein-appended drawings in which: Figure 1 is a plan view from above of a source- antenna system operating in three frequency bands, in accordance with the present invention. Figure 2 is a sectional view through A-A" of Figure 1. Figure 3 is a view from above of the lower substrate of the source-antenna system of Figures 1 and 2. Figure 4 is a sectional view of the "polyrod" used for transmission in Ka band in the system of Figures 1 and 2. Figures 5a-5b to 9a-9b respectively represent a view from above and a sectional view of various embodiments of radiating elements or "patches" used for receiving in Ku band and in accordance with the present invention. To simplify the description, the same references will be used in the various figures to designate the elements fulfilling the same functions or identical functions. We shall now describe with reference to Figures 1 to 4 a first embodiment of a source-antenna for transmitting/receiving electromagnetic waves operating in three frequency bands. More specifically and as represented in Figures 2 and 4, the source-antennas system comprises a first source-antenna used for transmission or uppath, which, in the embodiment represented, operates in the Ka band, namely around 30 GHz. As represented more particularly in Figures 2 and 4, the source-antenna structure used in this case consists essentially of a waveguide 12 terminating in a dielectric rod 11, this antenna structure being known , by the term "polyrod". The cross section of the waveguide 12 can be circular, rectangular, square or other. The shape of the cross section depends on the amount of room left free by the other two source- antenna structures, as will be explained hereinbelow. In the embodiment represented, the cross section of the waveguide is a circular section 12. As represented also in Figure 4, this cross section is filled with dielectric material whose purpose is to reduce the guided wavelength inside the guide. It is obvious to the person skilled in the art that other types of travelling-wave source-antennas may be used to embody the antenna structure of the uppath. Mention may be made, in particular, of helical antennas. A first embodiment of the two source-antenna structures used on reception, namely for the downpath, will now be described with reference to Figures 1 to 3. As represented more particularly in Figures 1 and 2, the source-antenna structure used for the downpath in the Ka band, namely around 20 GHz, consists of an array 20 of patches in linear polarization with two orthogonal polarizations and fed in series/parallel. More particularly, four patches 231, 232, 233, 234 of square shape arranged in a cross have been made on a substrate 21. The patches are arranged around the "polyrod" in such a way that their diagonal is at a distance D equal to 0.7 lg where lg is the guided wavelength. In the embodiment represented, the patches are connected as represented in Figure 1, namely the patch 231 is connected to the patch 232 by a line 241, the patch 232 is connected to the patch 233 by a line 244, the patch 233 is connected to the patch 234 by a line 243 and the patch 234 is connected to the patch 231 by a line 242. Moreover, the feed lines 26, 27 are connected in a specific manner on another input of the patches 231, 234, 233. The feed line 26 is connected by a line 251 to the patch 231, and by a line 252 to the patch 234 and the feed line 27 is connected to the patch 234 by a line 253 and to the patch 233 by a line 254 in such a manner as to produce a series/parallel feed. In this case, the lines 241, 242, 243 and 244 are of the same length. Given the gap between two patches, these lines have lengths like lg/2 modulo the guided wavelength. One embodiment of the transmission/reception source-antenna structure for the downpath used in the Ku band, namely between 10.7 GHz and 12.75 GHz, will now be described with reference to Figures 2 and 3. In this case, the antenna comprises an array of four patches. This array of patches is arranged in a square around the array of four patches in a cross used for the electromagnetic wave source-antenna in the Ka band, owing to its lower working frequency. As represented in Figure 2, the Ku band source- antenna structure is made by using two parallel substrates 21, 33 on which electromagnetically coupled parallel patches 321, 341 have been made, the lower substrate 33 being used to make the feed circuit which will be described subsequently and which can receive patches as represented in Figures 2 and 3, these electromagnetically coupled patches increasing the pass band. As represented in Figures 1 to 3, each patch 321, 322, 323, 324 is positioned on the first substrate 21 in a demetallized part 311, 312, 313, 314 of the layer 22 and the second substrate 33 on which a parallel patch 341 to 344 has been made receives the feed array. The feed array is represented in greater detail in Figure 3. In this case, each patch is fed at two points in such a way as to obtain the two orthogonal polarizations. More specifically, the patch 341 is connected to the point C2 of the first feed circuit by a line 351, the patch 344 is connected to the point C2 by a line 354, the patch 343 is connected to the point C1 by a line 353 and the patch 342 it connected to the point C1 by a line 352. The points C1 and C2 are connected to the point C3 respectively by a line 355 and 356, the point C3 being connected to a feed line. The length of the lines 353 and 354 is equal, likewise the length of the lines 352 and 311 is equal and such that length 352 - length 353 =lg/2. Moreover , the patch 343 is connected by a second input to the point C4 by a line 363, the patch 342 is connected to the point C4 by a line 362, the patch 341 is connected to the point C5 by a line 361, the patch 344 is connected to the point C5 by a line 364, the point C4 being connected to the point C6 by a Kne 366 and the point C5 being connected to the point C6 by a line 365. The point C6 is connected to another feed in such a way as to obtain a parallel feed. In the second case, the lines 361, 362, 363, 364 are of the same length and the difference DL between the length of the line 365 and the length of the line 366=lg/2. The various feed lines are connected in a known manner to reception circuits comprising at least a low-noise amplifier and a frequency converter. The circuits being weft known to the person skilled in the art, they will not be described in greater detail. Thus, with the circuit described hereinabove, the patches 341, 342, 343, 344 are all fed in phase and with the same amplitude by two power dividers made in microstrip technology, the feeding of the patches having to be done in phase so that the electric fields add together in the direction of propagation of the guided waves. Specifically, the phase shift d between two horizontally polarized waves is equal to d = b* DL where b = (2p/Ag), lg being equal to the wavelength of the guided wave. In the embodiment represented, the patches are excited via opposite lateral sides. Thus, the patch 341 is excited via its toft lateral side, this creating, at an instant t, a field E oriented from left to right while simultaneously the patch 344 is excited via its right lateral side which creates at the same instant t a field E oriented from right to left ultimately giving out-of-phase fields. By introducing a wavelength difference given by the difference of the length of the lines 351 and 354 which is equal to lg/2, a further phase shift d is created such that d = b* DL = (2P/lg)*x (lg/2) = P, thereby cancelling out the difference of the phases between the said electric fields. This configuration improves the quality of the polarization, since it eliminates the problems of cross polarization. Various embodiments of the patches used in the framework of the Ku band reception source-antenna structure will now be described with reference to Figures 5a-5b to 9a-9b. Various figures represent the lower right part of the system of Figure 1. Represented in Figures 5a-5b is another embodiment of the patches. In this case, a patch 302 with square shape has been deposited on the upper substrate 300. As represented clearly in the figure, the earth plane 301 has been recessed in such a way as to form a window 303 facilitating radiation. Moreover, a second patch 306 electromagnetically coupled to the first patch 302 is made parallel to the first patch 302 on the lower substrate 304. The patch 306 is fed by the lines 307 and 307" in two orthogonal sides. In accordance with this embodiment, metal walls 304 are provided plumb with the window 303 in such a way as to favour forward radiation of the superimposed patches 306 and 302. The part between the two substrates 305- 300 is filled with air. According to a variant, it could be filled with a material such as a foam. Represented in Figures 6a and 6b is another embodiment with superimposed patches. In this case, the upper substrate 310 furnished with the earth plane 311 is recessed to form a window 314. The part lying between the upper substrate 310 and the lower substrate 315 is filled with foam. The patch 312 is made on the foam and is coupled electromagnetically to the patch 316 made on the lower substrate 315. The patch 316 is fed like the patch 306 of Figures 5a and 5b by the lines 317 and 317". Yet another embodiment has been represented in Figures 7a and 7b. In this case, a patch 322 has been made on the upper substrate 320 in the window 323 obtained by demetallizing the earth plane 321. The feed circuit formed at least of the lines 327 and 327" is made on the lower substrate 325 furnished with an earth plane 326. In this case, the patch 322 is coupled electromagnetically with the lines 327, 327". The embodiments of Figures 8a and 8b and Figures 9a and 9b are akin to a radiating aperture. Thus, as represented in Figures 8a and 8b, the upper substrate 330 furnished with its earth plane 331 is recessed to form a window 333. In the embodiment represented, the upper substrate 330 is mounted on the lower substrate 335 with interposition of the metal walls 334. The feed lines 337, 337" are made on the lower substrate 335. In this case, the radiating aperture thus made is excited by probes. In the variant represented in Figures 9a and 9b, a patch 336 is made on the lower substrate 335. This patch 336 is connected to the feed lines 337, 337" in a conventional manner. The embodiments described hereinabove by way of example make it possible to incorporate a source- antenna in reception operating in the Ka band with a source-antenna in reception operating in the Ku band, the two antennas being cofocused. It is obvious to the person skilled in the art that the frequency bands are given by way of illustration and that the invention can also operate in other bands. It is obvious to the person skilled in the art that other types of arrays could be used to produce the source-antennas structures used on reception, in particular any type of array comprising radiating elements with linear or circular, orthogonal double polarization. WE CLAIM: 1. Source antenna for transmitting/receiving electromagnetic waves comprising means (11) for transmitting electromagnetic waves with longitudinal radiation operating in a first frequency band and means for receiving electromagnetic waves, characterized in that the means for receiving electromagnetic waves consist of a first array (231- 234) of n radiating elements operating in a second frequency band and a second array (321 - 324 - 341 - 344) of n" radlating elements operating in a third frequency band, the first and second arrays and the longitudinal-radiation means having a substantially common phase center and the radiating elements of the first and second arrays being arranged around the longitudinal-radiation means. 2. Source antenna as claimed in claim 1, wherein the first array of n radiating elements consists of an array of n patches (231 - 234) having linear or circular, orthogonal double polarization. 3. Source antenna as claimed in claim 2, wherein the first array of n patches is connected to a feed circuit (241 - 244, 251 - 254, 26, 27) made in microstrip technology on a first substrate. 4. Source antenna as claimed in any one of claims 1 to 3, wherein the means for transmitting electromagnetic waves with longitudinal notation consist of an antenna of the longitudinal-radiation travelling wave type with axis coinciding with the axis of radiation, excited by means (12) comprising a waveguide. 5. Source antenna as claimed in claim 4, wherein the antenna of the longitudinal-radiation traveling wave type consists of a dielectric rod known as a "polyrod" (11) or of a helix. 6. Source antenna as claimed in claim 4, wherein the waveguide is filled with a dielectric material. 7. Source antenna as claimed in any one of claims 1 to 6, wherein the second array of n" radiating dements consists of an array of n1 radiating elements (321 - 324; 341 -344) having linear or circular, orthogonal double polarization and a wide band. 8. Source antenna as claimed in claim 7, wherein the array of n" elements having linear or circular, orthogonal double polarization with a wide band is made by using two parallel substrates (21, 33), one of the substrates being the first substrate (21) receiving the first array. 9. Source antenna as claimed in claim 8, wherein the first substrate (21) is covered with a metallic layer (22) forming an earth plane comprising demetallized zones (311 - 314), at the level of the radiating elements of the second array. 10. Source antenna as claimed in claims 7 to 9, wherein the radiating elements of the array with linear or circular, orthogonal double polarization and a wide band consist of two patches (321 - 341; 302 - 306; 312 - 316) which are superimposed and made respectively on each substrate and coupled electromagnetically. 11. Source antenna as claimed in claim 10, wherein the two substrates are connected plumb with the demetallized zones (303) by metallic walls (304). 12. Source antenna as claimed in claims 7 to 9, wherein the radiating elements of the array with linear or circular, orthogonal double polarization and with a wide band consist of a patch (322) coupled electromagnetically to a probe (327, 327") connected to the feed circuit. 13. Source antenna as claimed in claims 7 to 9, wherein the radiating elements of the array with linear or circular, orthogonal double polarization and a wide band consist of an aperture (333) made in the first substrate (330) and a probe (337, 337") connected to the feed circuit and made on the parallel substrate. 14. Source antenna at claimed in claims 7 to 9, wherein the radiating elements of the array with linear or circular, orthogonal double polarization and a wide band consist of an aperture (333) made in the first substrate (330) and a patch (336) connected to the feed circuit and made on the parallel substrate. 15. Source antenna as claimed in claims 7 to 14, wherein the second array of n" radieting elements is connected to a feed circuit made in microstrip technology. 16. Source antenna as claimed in claims 1 to 14, wherein the first array of n radiating elements is an array with four elements arranged in a square and in that the second array of n" radiating elements is an array with four elements arranged in a cross around the first array. 17. Source antenna as claimed in any one of claims 1 to 16, wherein the first and second frequency bands correspond to the Ka band and the third frequency band corresponds to the Ku band. The Invention relates to an improvement to a compact, low cost and hybrid waveguide/microstrip feed such that for the high frequency transmitting band, the feed is realised in a W/G technology using a well known compact polyrod feed solution, and for the low frequency receiving band, the feed is realized in a microstrip technology. In order to ensure the necessary wide frequency bandwidth, a small array of dual band electromagnetically coupled patch antennas is used. This antenna operates within two frequency bands. The present invention proposes a new structure able to operate within three frequency bands. According to the invention, the antenna feed comprises a second network of n" radiating elements operating in a third frequency band. This invention is used for satellite antennas.

Full Text

The present invention relates to a source-
antenna for transmitting/receiving electromagnetic
waves, more particularly a system of source-antennas
allowing the reception of satellite television signals
in a certain frequency band such as the Ku band lying
between 10.7 and 12.75 GHz and of satellite
communications in a second frequency band such as the
Ka band at around 30 GHz in transmission and at around
20 GHz in reception, using just a single structure of
antennas.
There are at present source-antenna structures
for transmitting/receiving electromagnetic waves which
operate with two frequency bands. These source-antennas
make it possible to meet the requirements of satellite
communication systems in respect of high bit rate
multimedia applications. An antenna of this type has
been proposed in patent WO 99/357/1 in the name of
THOMSON multimedia. These dual-band antenna structures
are composed of two cofocused antennas. Thus, as
described in the abovementioned patent application, the
first antenna used for reception or downpath consists
of an array of n patches. This array can be used in
linear or circular polarization and benefit from two
orthogonal polarizations. The second antenna used for
transmission or uppath consists of a waveguide
terminating in a dielectric rod commonly referred to as
a "polyrod". This antenna can be used in linear or
circular polarization and benefit from two orthogonal
polarizations. These two antennas are made in such a
way that the phase centres of the "polyrod" and of the
array of patches practically coincide and can be placed
at the focus of the system of antennas.
The aim of the present invention is to
incorporate into a transmission/reception source-
antenna structure operating in two frequency bands
another source-antenna structure which operates in
respect of reception, namely the downpath, at a lower
working frequency than the other two frequencies, more
particularly in a frequency band allowing the reception
of conventional satellite television signals. This
makes it possible to obtain an antenna structure
operating on three frequency bands.
Thus, the subject of the present invention is a
source antenna for transmitting/receiving
electromagnetic waves comprising means for transmitting
electromagnetic waves with longitudinal radiation
operating in a first frequency band and means for
receiving electromagnetic waves, characterized in that
the means for receiving electromagnetic waves consist
of a first array of n radiating elements operating in a
second frequency band and a second array of n"
radiating elements operating in a third frequency band,
the first and second arrays and the longitudinal-
radiation means having a substantially common phase
centre and the radiating elements of the first and
second arrays being arranged around the longitudinal-
radiation means.
According to one embodiment, the first array of
n radiating elements consists of an array of n patches
having linear or circular, orthogonal double
polarization, the first array of n patches being
connected to a feed circuit made in microstrip
technology on a first substrate.
Moreover, the means for transmitting
electromagnetic waves with longitudinal radiation
consist of an antenna of the longitudinal-radiation
travelling wave type with axis coinciding with the axis
of radiation, excited by means comprising a waveguide,
the waveguide being filled with a dielectric material.
This makes it possible to restrict the dimensions of
the cross section of the waveguide and to reduce the
guided wavelength inside the guide. Moreover, the
antenna of the travelling wave type may consist of a
dielectric rod known as a "polyrod" or of a helix.
Furthermore, the second array of n" radiating
elements consists of an array of n" radiating elements
having linear or circular, orthogonal double
polarization and a wide band. This array is made,
preferably, by using two parallel substrates, one of
the substrates being the first substrate receiving the
first array.
According to a first embodiment, the substrate
is covered with a metallic layer forming an earth plane
comprising demetallized zones, at the level of the
radiating elements of the second array.
According to a preferred embodiment, the
radiating elements of the array with orthogonal double
polarization and a wide band consist of two patches
which are superimposed and made respectively on each
substrate and coupled electromagnetically. In this
case, the two substrates may be connected plumb with
the demetallized zones by metallic walls.
According to another embodiment, the radiating
elements of the array with orthogonal double
polarization and with a wide band consist of a patch
coupled electromagnetically to a probe connected to the
feed circuit.
According to yet another embodiment, the
radiating elements of the array with orthogonal double
polarization and a wide band consist of an aperture
made in the first substrate and a probe connected to
the feed circuit and made on the parallel substrate.
According to yet another embodiment, the
radiating elements of the array with orthogonal double
polarization and a wide band consist of an aperture
made in the first substrate and a patch connected to
the feed circuit and made on the parallel substrate.
Moreover, the second array of n" radiating
elements is connected to a feed circuit made in
microstrip technology.
According to a characteristic of the present
invention, the first array of n radiating elements is
an array with four elements arranged in a square and
the second array of n" radiating elements is an array
with four elements arranged in a cross around the first
array.
In accordance with the present invention, the
first and second frequency bands correspond to the Ka
band and the third frequency band corresponds to the Ku
band.
Other characteristics and advantages of the
present invention will become apparent on reading the
following description, this description being given
with reference to the herein-appended drawings in
which:
Figure 1 is a plan view from above of a source-
antenna system operating in three frequency bands, in
accordance with the present invention.
Figure 2 is a sectional view through A-A" of
Figure 1.
Figure 3 is a view from above of the lower
substrate of the source-antenna system of Figures 1 and
2.
Figure 4 is a sectional view of the "polyrod"
used for transmission in Ka band in the system of
Figures 1 and 2.
Figures 5a-5b to 9a-9b respectively represent a
view from above and a sectional view of various
embodiments of radiating elements or "patches" used for
receiving in Ku band and in accordance with the present
invention.
To simplify the description, the same
references will be used in the various figures to
designate the elements fulfilling the same functions or
identical functions.
We shall now describe with reference to Figures
1 to 4 a first embodiment of a source-antenna for
transmitting/receiving electromagnetic waves operating
in three frequency bands. More specifically and as
represented in Figures 2 and 4, the source-antennas
system comprises a first source-antenna used for
transmission or uppath, which, in the embodiment
represented, operates in the Ka band, namely around
30 GHz.
As represented more particularly in Figures 2
and 4, the source-antenna structure used in this case
consists essentially of a waveguide 12 terminating in a
dielectric rod 11, this antenna structure being known
,
by the term "polyrod". The cross section of the
waveguide 12 can be circular, rectangular, square or
other. The shape of the cross section depends on the
amount of room left free by the other two source-
antenna structures, as will be explained hereinbelow.
In the embodiment represented, the cross
section of the waveguide is a circular section 12. As
represented also in Figure 4, this cross section is
filled with dielectric material whose purpose is to
reduce the guided wavelength inside the guide. It is
obvious to the person skilled in the art that other
types of travelling-wave source-antennas may be used to
embody the antenna structure of the uppath. Mention may
be made, in particular, of helical antennas.
A first embodiment of the two source-antenna
structures used on reception, namely for the downpath,
will now be described with reference to Figures 1 to 3.
As represented more particularly in Figures 1 and 2,
the source-antenna structure used for the downpath in
the Ka band, namely around 20 GHz, consists of an array
20 of patches in linear polarization with two
orthogonal polarizations and fed in series/parallel.
More particularly, four patches 231, 232, 233, 234 of
square shape arranged in a cross have been made on a
substrate 21. The patches are arranged around the
"polyrod" in such a way that their diagonal is at a
distance D equal to 0.7 lg where lg is the guided
wavelength.
In the embodiment represented, the patches are
connected as represented in Figure 1, namely the patch
231 is connected to the patch 232 by a line 241, the
patch 232 is connected to the patch 233 by a line 244,
the patch 233 is connected to the patch 234 by a line
243 and the patch 234 is connected to the patch 231 by a
line 242. Moreover, the feed lines 26, 27 are connected
in a specific manner on another input of the patches
231, 234, 233. The feed line 26 is connected by a line
251 to the patch 231, and by a line 252 to the patch 234
and the feed line 27 is connected to the patch 234 by a
line 253 and to the patch 233 by a line 254 in such a
manner as to produce a series/parallel feed. In this
case, the lines 241, 242, 243 and 244 are of the same
length. Given the gap between two patches, these lines
have lengths like lg/2 modulo the guided wavelength.
One embodiment of the transmission/reception
source-antenna structure for the downpath used in the
Ku band, namely between 10.7 GHz and 12.75 GHz, will
now be described with reference to Figures 2 and 3. In
this case, the antenna comprises an array of four
patches. This array of patches is arranged in a square
around the array of four patches in a cross used for
the electromagnetic wave source-antenna in the Ka band,
owing to its lower working frequency.
As represented in Figure 2, the Ku band source-
antenna structure is made by using two parallel
substrates 21, 33 on which electromagnetically coupled
parallel patches 321, 341 have been made, the lower
substrate 33 being used to make the feed circuit which
will be described subsequently and which can receive
patches as represented in Figures 2 and 3, these
electromagnetically coupled patches increasing the pass
band. As represented in Figures 1 to 3, each patch 321,
322, 323, 324 is positioned on the first substrate 21 in
a demetallized part 311, 312, 313, 314 of the layer 22
and the second substrate 33 on which a parallel patch
341 to 344 has been made receives the feed array. The
feed array is represented in greater detail in
Figure 3. In this case, each patch is fed at two points
in such a way as to obtain the two orthogonal
polarizations. More specifically, the patch 341 is
connected to the point C2 of the first feed circuit by
a line 351, the patch 344 is connected to the point C2
by a line 354, the patch 343 is connected to the point C1 by a line 353
and the patch 342 it connected to the point C1 by a line 352. The points
C1 and C2 are connected to the point C3 respectively by a line 355 and
356, the point C3 being connected to a feed line. The length of the lines
353 and 354 is equal, likewise the length of the lines 352 and 311 is equal
and such that length 352 - length 353 =lg/2. Moreover , the patch 343 is
connected by a second input to the point C4 by a line 363, the patch 342
is connected to the point C4 by a line 362, the patch 341 is connected to
the point C5 by a line 361, the patch 344 is connected to the point C5 by
a line 364, the point C4 being connected to the point C6 by a Kne 366 and
the point C5 being connected to the point C6 by a line 365. The point C6
is connected to another feed in such a way as to obtain a parallel feed.
In the second case, the lines 361, 362, 363, 364 are of the same length
and the difference DL between the length of the line 365 and the length
of the line 366=lg/2.
The various feed lines are connected in a known manner to
reception circuits comprising at least a low-noise amplifier and a
frequency converter. The circuits being weft known to the person skilled
in the art, they will not be described in greater detail. Thus, with the
circuit described hereinabove, the patches 341, 342, 343, 344 are all fed
in phase and with the same amplitude by two power dividers made in
microstrip technology, the feeding of the patches having to be done in
phase so that the electric fields add together in the direction of
propagation of the guided waves. Specifically, the phase shift d between
two horizontally polarized waves is equal to d = b* DL where b = (2p/Ag),
lg being equal to the wavelength of the guided wave.
In the embodiment represented, the patches are excited via
opposite lateral sides. Thus, the patch 341 is excited via its toft lateral
side, this creating, at an instant t, a field E oriented from left to right
while simultaneously the patch 344 is excited via its
right lateral side which creates at the same instant t
a field E oriented from right to left ultimately giving
out-of-phase fields. By introducing a wavelength
difference given by the difference of the length of the
lines 351 and 354 which is equal to lg/2, a further
phase shift d is created such that d = b* DL =
(2P/lg)*x (lg/2) = P, thereby cancelling out the
difference of the phases between the said electric
fields. This configuration improves the quality of the
polarization, since it eliminates the problems of cross
polarization.
Various embodiments of the patches used in the
framework of the Ku band reception source-antenna
structure will now be described with reference to
Figures 5a-5b to 9a-9b. Various figures represent the
lower right part of the system of Figure 1.
Represented in Figures 5a-5b is another
embodiment of the patches. In this case, a patch 302
with square shape has been deposited on the upper
substrate 300. As represented clearly in the figure,
the earth plane 301 has been recessed in such a way as
to form a window 303 facilitating radiation. Moreover,
a second patch 306 electromagnetically coupled to the
first patch 302 is made parallel to the first patch 302
on the lower substrate 304. The patch 306 is fed by the
lines 307 and 307" in two orthogonal sides. In
accordance with this embodiment, metal walls 304 are
provided plumb with the window 303 in such a way as to
favour forward radiation of the superimposed patches
306 and 302. The part between the two substrates 305-
300 is filled with air. According to a variant, it
could be filled with a material such as a foam.
Represented in Figures 6a and 6b is another
embodiment with superimposed patches. In this case, the
upper substrate 310 furnished with the earth plane 311
is recessed to form a window 314. The part lying
between the upper substrate 310 and the lower substrate
315 is filled with foam. The patch 312 is made on the
foam and is coupled electromagnetically to the patch
316 made on the lower substrate 315. The patch 316 is
fed like the patch 306 of Figures 5a and 5b by the
lines 317 and 317".
Yet another embodiment has been represented in
Figures 7a and 7b. In this case, a patch 322 has been
made on the upper substrate 320 in the window 323
obtained by demetallizing the earth plane 321. The feed
circuit formed at least of the lines 327 and 327" is
made on the lower substrate 325 furnished with an earth
plane 326. In this case, the patch 322 is coupled
electromagnetically with the lines 327, 327".
The embodiments of Figures 8a and 8b and
Figures 9a and 9b are akin to a radiating aperture.
Thus, as represented in Figures 8a and 8b, the upper
substrate 330 furnished with its earth plane 331 is
recessed to form a window 333. In the embodiment
represented, the upper substrate 330 is mounted on the
lower substrate 335 with interposition of the metal
walls 334. The feed lines 337, 337" are made on the
lower substrate 335. In this case, the radiating
aperture thus made is excited by probes.
In the variant represented in Figures 9a and
9b, a patch 336 is made on the lower substrate 335.
This patch 336 is connected to the feed lines 337, 337"
in a conventional manner.
The embodiments described hereinabove by way of
example make it possible to incorporate a source-
antenna in reception operating in the Ka band with a
source-antenna in reception operating in the Ku band,
the two antennas being cofocused.
It is obvious to the person skilled in the art
that the frequency bands are given by way of
illustration and that the invention can also operate in
other bands.
It is obvious to the person skilled in the art
that other types of arrays could be used to produce the
source-antennas structures used on reception, in
particular any type of array comprising radiating
elements with linear or circular, orthogonal
double polarization.
WE CLAIM:
1. Source antenna for transmitting/receiving electromagnetic waves
comprising means (11) for transmitting electromagnetic waves with
longitudinal radiation operating in a first frequency band and means for
receiving electromagnetic waves, characterized in that the means for
receiving electromagnetic waves consist of a first array (231- 234) of n
radiating elements operating in a second frequency band and a second
array (321 - 324 - 341 - 344) of n" radlating elements operating in a third
frequency band, the first and second arrays and the longitudinal-radiation
means having a substantially common phase center and the radiating
elements of the first and second arrays being arranged around the
longitudinal-radiation means.
2. Source antenna as claimed in claim 1, wherein the first array of n
radiating elements consists of an array of n patches (231 - 234) having
linear or circular, orthogonal double polarization.
3. Source antenna as claimed in claim 2, wherein the first array of n patches
is connected to a feed circuit (241 - 244, 251 - 254, 26, 27) made in
microstrip technology on a first substrate.
4. Source antenna as claimed in any one of claims 1 to 3, wherein the
means for transmitting electromagnetic waves with longitudinal notation
consist of an antenna of the longitudinal-radiation travelling wave type with
axis coinciding with the axis of radiation, excited by means (12)
comprising a waveguide.
5. Source antenna as claimed in claim 4, wherein the antenna of the
longitudinal-radiation traveling wave type consists of a dielectric rod
known as a "polyrod" (11) or of a helix.
6. Source antenna as claimed in claim 4, wherein the waveguide is filled with
a dielectric material.
7. Source antenna as claimed in any one of claims 1 to 6, wherein the
second array of n" radiating dements consists of an array of n1 radiating
elements (321 - 324; 341 -344) having linear or circular, orthogonal double
polarization and a wide band.
8. Source antenna as claimed in claim 7, wherein the array of n" elements
having linear or circular, orthogonal double polarization with a wide band
is made by using two parallel substrates (21, 33), one of the substrates
being the first substrate (21) receiving the first array.
9. Source antenna as claimed in claim 8, wherein the first substrate (21) is
covered with a metallic layer (22) forming an earth plane comprising
demetallized zones (311 - 314), at the level of the radiating elements of the
second array.
10. Source antenna as claimed in claims 7 to 9, wherein the radiating
elements of the array with linear or circular, orthogonal double polarization
and a wide band consist of two patches (321 - 341; 302 - 306; 312 - 316)
which are superimposed and made respectively on each substrate and
coupled electromagnetically.
11. Source antenna as claimed in claim 10, wherein the two substrates are
connected plumb with the demetallized zones (303) by metallic walls
(304).
12. Source antenna as claimed in claims 7 to 9, wherein the radiating
elements of the array with linear or circular, orthogonal double polarization
and with a wide band consist of a patch (322) coupled electromagnetically
to a probe (327, 327") connected to the feed circuit.
13. Source antenna as claimed in claims 7 to 9, wherein the radiating
elements of the array with linear or circular, orthogonal double polarization
and a wide band consist of an aperture (333) made in the first substrate
(330) and a probe (337, 337") connected to the feed circuit and made on
the parallel substrate.
14. Source antenna at claimed in claims 7 to 9, wherein the radiating
elements of the array with linear or circular, orthogonal double polarization
and a wide band consist of an aperture (333) made in the first substrate
(330) and a patch (336) connected to the feed circuit and made on the
parallel substrate.
15. Source antenna as claimed in claims 7 to 14, wherein the second array of
n" radieting elements is connected to a feed circuit made in microstrip
technology.
16. Source antenna as claimed in claims 1 to 14, wherein the first array of n
radiating elements is an array with four elements arranged in a square and
in that the second array of n" radiating elements is an array with four
elements arranged in a cross around the first array.
17. Source antenna as claimed in any one of claims 1 to 16, wherein the first
and second frequency bands correspond to the Ka band and the third
frequency band corresponds to the Ku band.
The Invention relates to an improvement to a compact, low cost and hybrid
waveguide/microstrip feed such that for the high frequency transmitting band, the
feed is realised in a W/G technology using a well known compact polyrod feed
solution, and for the low frequency receiving band, the feed is realized in a
microstrip technology. In order to ensure the necessary wide frequency
bandwidth, a small array of dual band electromagnetically coupled patch
antennas is used. This antenna operates within two frequency bands. The
present invention proposes a new structure able to operate within three
frequency bands. According to the invention, the antenna feed comprises a
second network of n" radiating elements operating in a third frequency band. This
invention is used for satellite antennas.

Documents:

http://ipindiaonline.gov.in/documentkol/321-CAL-2001/321-CAL-2001-FORM-27.pdf

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Patent Number

216344

Indian Patent Application Number

321/CAL/2001

PG Journal Number

11/2008

Publication Date

14-Mar-2008

Grant Date

12-Mar-2008

Date of Filing

31-May-2001

Name of Patentee

THOMSON LICENSING,S.A

Applicant Address

46 QUAI A.LE GALIO, F-92100 BOULOGNE BILLANCOURT FRANCE

Inventors:

#	Inventor's Name	Inventor's Address
1	FORDEUX HENRI	L SUDRAIS F-35150 CORPS-NUDS, ARANCE NATIONAL
2	MINARD PHILIPPE	17 DWUSTR FU BOID PRTTIN F-35700 RENNES FRANCE
3	LOUZIR ALI	6 RUE DE LA GODMONDIERE F-35000 RENNES TUNISIA.

PCT International Classification Number

G01 F 23/32

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA