Title of Invention	"A MICROWAVE CORRUGATED-HORN ANTENNA AND A PROCESS FOR MANUFACTURING THE SAME"
Abstract	A manufacturing process for a microwave corrugated-horn antenna (5) using waveguide technology, characterized in that it comprises the steps of: conforming a block of foam (3) of synthetic material into a horn, - forming corrugations (6) on whole external surface of the foam block by deforming such external surface, and metallizing the external surface of the foam block provided with corrugations.

Title of Invention

"A MICROWAVE CORRUGATED-HORN ANTENNA AND A PROCESS FOR MANUFACTURING THE SAME"

Abstract

A manufacturing process for a microwave corrugated-horn antenna (5) using waveguide technology, characterized in that it comprises the steps of: conforming a block of foam (3) of synthetic material into a horn, - forming corrugations (6) on whole external surface of the foam block by deforming such external surface, and metallizing the external surface of the foam block provided with corrugations.

Full Text	MANUFACTURING PROCESS FOR A NICROWAVE ANTENNA USING WAVEGUJJMC TECHNOLOGY The invention relates to a manufacturing process for a microwave corrugated-horn antenna using waveguide technology. This type of antenna is generally made up of several molded parts. In particular, for making the corrugated horn, the manufacturing process consists * in molding two half-parts that are symmetrical relative to an axial plane of the horn. The number of molds required for the manufacture of the various elements of such an antenna can become prohibitive with a view to high-volume, low-cost production. Moreover, the alignment and interconnection of the various elements of the antenna, in order to limit the electrical discontinuities, lead to manufacturing constraints that impact the production cost of the antenna. Figure 1 shows a perspective view of an example of a microwave antenna using waveguide technology comprising a corrugated horn 1 with, amongst other features, a frequency separator 2. The corrugated horn 1 is formed by assembly- of'-two symmetrical"'half-parts. The use of blocks of synthetic foam, such as polymethacrylimide, for constructing microwave devices using waveguide technology is known from the document "Foam technology for integration of microwave 3D functions" - ELECTRONICS LETTERS 14 October 1999 - Vol.35 N°21. In particular, this document proposes the construction of a 3D bandpass filter by molding of a block of foam. A manufacturing process for a horn antenna, according to the abstract of the Japanese patent JP-A-59107607, is also known that consists in rolling a fiber-reinforced plastic into the grooves of a conical mold so as to form a corrugated horn whose corrugations are metallized. A process for depositing a metallic film onto a block of foam for manufacturing microwave antennas using waveguide technology is also known from the French patent document n°2780319. The aim of the invention is to propose a process for manufacturing, from a block of synthetic foam, a microwave corrugated-horn antenna using waveguide technology, which process is designed for low-cost volume production, but which avoids the drawbacks » indicated above. The process according to the invention consists in forming the corrugations of the horn on the external surface of a block of synthetic foam and in subsequently metallizing the surface of the conformed block of foam to form the antenna. With this process, the corrugated horn can be manufactured as a single piece, which will contribute to eliminate the electrical discontinuities in the antenna. The conformation of the external surface of the block of foam for forming the corrugations of the horn is preferably obtained by thermoforming according to a hot-press molding technique. The preform of the block of foam used for forming the horn will preferably be "substantially conical/. .y•••<::>^'••;i.:* The surface metallization of the block of foam is preferably carried out by projection or using a brush, or alternatively by dipping in a metallic bath. The synthetic material used for the foam will preferably be a polymethacrylimide foam, marketed under the name of "ROHACELL HF", that exhibits, amongst other advantages, a good compromise between rigidity, low dielectric constant and low losses. In addition, the external surface of several sections of the same block of foam can be conformed by hot pressing in a mold in order to form, as a single piece, a microwave antenna comprising, successively, a corrugated horn, an impedance adapter and a polarizer. A microwave antenna polarizer using waveguide technology can be formed by insertion of two metal plates inside a circular waveguide, these two parts being disposed symmetrically with respect to one another in an axial plane of the circular waveguide. These parts are formed (length, profile), in a known manner, such that they allow the phase of a mode whose electric field E is in the plane of the metal plates to be delayed by 90° relative to a mode whose i field E is perpendicular to the plane of the plates, thus obtaining a circular polarization at the exit of the polarizer, starting from a field at the entry that has a linear polarization in a plane situated at 45° from the plane of the plates and vice versa. Two radial slots are formed by hot pressing on a cylindrical section of the block of foam, in which the corrugated horn is formed, and the surface of this cylindrical section is then metallized in order to form the polarizer. On another cylindrical section of the same block of foam, a circular groove forming a narrowing in the cross-section of the cylindrical section is formed by hot pressing and the surface of this other cylindrical section is then metallized in order ^tb" form the impedance adapter. .-• - >::yt-;';:. The process according to the invention is described below in relation to the drawings. Figure 1 shows a perspective view of a microwave antenna using waveguide technology that comprises a corrugated horn. Figure 2 illustrates very schematically a molding operation by hot pressing of a block of foam according to the invention in order to form a corrugated horn using waveguide technology as a single piece. Figure 3 shows an axial cross-section of the corrugated horn obtained with the process according to the invention. Figure 4 illustrates very schematically a molding * operation by hot pressing of a block of foam according to the invention in order to form a polarizer using waveguide technology. Figure 5 shows an axial cross-section of the polarizer obtained with the process according to the invention. Figure 6 shows an axial cross-section of a microwave antenna produced with the process according to the .invention. Figure 2 shows a preform of substantially conical shape from a block of synthetic foam 3 . This preform is conformed in a mold • 4 by hot pressing in order to form a corrugated horn 5 shown in figure 3. Here, the synthetic foam is a polymethacrylimide foam marketed .under the name of "ROHACELL HF%. The corrugations • &.; of•the horn are formed on the external surface of the block of foam 3 by thermoforming. The surface of the conformed block of foam 3 is then metallized in order to form the corrugated horn. The heavy line 7 on the external surface of the block of foam 3 represents the metallic coating of the block of foam. Figure 4 shows a preform of substantially cylindrical shape from a block of synthetic foam 3'. This preform is conformed in a mold 4' by hot pressing in order to form a polarizer 8 shown in figure 5. The conformation consists in the formation of two radial slots 9, 10 in the block of foam 3' that are symmetrical in an axial plane of the cylindrical block of foam. The surface of the conformed block of foam 3' is then metallized as shown by the heavy line 11. Figure 6 now shows a microwave antenna produced using waveguide technology according to the process of the invention. The antenna comprises a corrugated horn such as 5 that is excited by a circular waveguide polarizer such as 8 together with an impedance adapter 13. The antenna is formed as a single piece from a thermoformed block of foam. More particularly, on the external surface of a first section of the block of foam of conical shape, the corrugations of the horn have been formed by thermof orming. On the external surface of a second section of the block of foam of cylindrical shape, a circular groove 12 has been formed by thermof orming in order to form the - impedance adapter. On the external surface of a third~ section of the block of foam of cylindrical shape, two radial slots have been formed by thermoforming in order to form the polarizer. The thermof orming of the:; three sections of the block of foam is carried out in a single step using a single mold. In the case where a polymethacrylimide foam is used, the preform is preheated to around 150°C in order to ,r.s;Qfiteen>; . it for insertion into the "mold. Once the,*> preform has been inserted into the mold, a suitable temperature profile is applied, for both the temperature rise phase up to 180°C and for the temperature decrease, with a progressive application of pressure. The removal from the mold is effected at room temperature or slightly higher. Subsequently, the surfaces of the sections of the block of foam are metallized by projection of a metallic paint of the silver type or derivative thereof, or alternatively using a brush or by dipping into a metallic bath as indicated above. The metallic coating on the surface of the block of foam (depicted with hatching) is represented by the heavy line in figure 6. 1. A manufacturing process for a microwave corrugated-horn antenna (5) using waveguide technology, characterized in that it comprises the steps of: conforming a block of foam (3) of synthetic material into a horn, - forming corrugations (6) on whole external surface of the foam block by deforming such external surface, and metallizing the external surface of the foam block provided with corrugations. 2. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in claim 1, wherein the corrugations of the horn are formed by hot pressing of the block of foam in a mold (4). 3. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in claim 1 or 2, wherein the metallization of the surface of the block of foam is carried out by projection or using a brush, or alternatively by dipping. 4. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in one of claims 1 to 3, wherein two radial slots (9, 10) are formed in a cylindrical section of the block of foam by thermoforming and the surface of this section of the block of foam is metallized in order to form a waveguide polarizer. 5. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in one of claims 1 to 4, wherein a circular groove (12) is formed in another section of the block of foam by thermoforming and the surface of this other section of the block of foam is metallized in order to form an impedance adapter. 6. A microwave corrugated-horn antenna (5) using waveguide technology characterized in that formed from a block of synthetic foam (3) having, on its external surface, corrugations (6) obtained by deformation of said surface, said corrugations (6) being metallized. 7. The microwave corrugated-horn antenna (5) as claimed in claim 6, wherein it comprises, in addition, a waveguide polarizer (8) formed by two radial slots (9, 10) formed in a first cylindrical section of the block of foam (3), this first section being metallized. 8. The microwave corrugated-horn antenna (5) as claimed in either of claims 6 and 7, wherein it comprises, in addition, an impedance adapter (13) formed by a circular groove (12) formed in a second section of the block of foam, this second section being metallized.

Full Text

MANUFACTURING PROCESS FOR A NICROWAVE ANTENNA USING
WAVEGUJJMC TECHNOLOGY
The invention relates to a manufacturing process for
a microwave corrugated-horn antenna using waveguide
technology.
This type of antenna is generally made up of several
molded parts. In particular, for making the
corrugated horn, the manufacturing process consists
*
in molding two half-parts that are symmetrical relative to an axial plane of the horn. The number of molds required for the manufacture of the various elements of such an antenna can become prohibitive with a view to high-volume, low-cost production. Moreover, the alignment and interconnection of the various elements of the antenna, in order to limit the electrical discontinuities, lead to manufacturing constraints that impact the production cost of the antenna.
Figure 1 shows a perspective view of an example of a microwave antenna using waveguide technology comprising a corrugated horn 1 with, amongst other features, a frequency separator 2. The corrugated horn 1 is formed by assembly- of'-two symmetrical"'half-parts.
The use of blocks of synthetic foam, such as polymethacrylimide, for constructing microwave devices using waveguide technology is known from the document "Foam technology for integration of microwave 3D functions" - ELECTRONICS LETTERS 14 October 1999 - Vol.35 N°21. In particular, this document proposes the construction of a 3D bandpass filter by molding of a block of foam. A manufacturing process for a horn antenna, according to the abstract of the Japanese patent JP-A-59107607, is also known that consists in rolling a fiber-reinforced plastic into the grooves of a conical mold so as to form a corrugated horn whose corrugations are metallized.
A process for depositing a metallic film onto a block of foam for manufacturing microwave antennas using waveguide technology is also known from the French patent document n°2780319.
The aim of the invention is to propose a process for manufacturing, from a block of synthetic foam, a microwave corrugated-horn antenna using waveguide technology, which process is designed for low-cost
volume production, but which avoids the drawbacks »
indicated above.
The process according to the invention consists in
forming the corrugations of the horn on the external
surface of a block of synthetic foam and in
subsequently metallizing the surface of the conformed
block of foam to form the antenna. With this process,
the corrugated horn can be manufactured as a single
piece, which will contribute to eliminate the
electrical discontinuities in the antenna.
The conformation of the external surface of the block
of foam for forming the corrugations of the horn is
preferably obtained by thermoforming according to a
hot-press molding technique. The preform of the block
of foam used for forming the horn will preferably be
"substantially conical/. .y•••<::>^'••;i.:* The surface metallization of the block of foam is preferably carried out by projection or using a brush, or alternatively by dipping in a metallic bath.
The synthetic material used for the foam will preferably be a polymethacrylimide foam, marketed under the name of "ROHACELL HF", that exhibits, amongst other advantages, a good compromise between rigidity, low dielectric constant and low losses. In addition, the external surface of several sections of the same block of foam can be conformed by hot pressing in a mold in order to form, as a single piece, a microwave antenna comprising, successively, a corrugated horn, an impedance adapter and a polarizer.
A microwave antenna polarizer using waveguide technology can be formed by insertion of two metal plates inside a circular waveguide, these two parts being disposed symmetrically with respect to one another in an axial plane of the circular waveguide. These parts are formed (length, profile), in a known manner, such that they allow the phase of a mode whose electric field E is in the plane of the metal plates to be delayed by 90° relative to a mode whose
i
field E is perpendicular to the plane of the plates, thus obtaining a circular polarization at the exit of the polarizer, starting from a field at the entry that has a linear polarization in a plane situated at 45° from the plane of the plates and vice versa. Two radial slots are formed by hot pressing on a cylindrical section of the block of foam, in which the corrugated horn is formed, and the surface of this cylindrical section is then metallized in order to form the polarizer. On another cylindrical section of the same block of foam, a circular groove forming a narrowing in the cross-section of the cylindrical section is formed by hot pressing and the surface of this other cylindrical section is then metallized in order ^tb" form the impedance adapter. .-• - >::yt-;';:. The process according to the invention is described below in relation to the drawings.
Figure 1 shows a perspective view of a microwave antenna using waveguide technology that comprises a corrugated horn.
Figure 2 illustrates very schematically a molding operation by hot pressing of a block of foam according to the invention in order to form a corrugated horn using waveguide technology as a single piece.
Figure 3 shows an axial cross-section of the corrugated horn obtained with the process according to the invention.
Figure 4 illustrates very schematically a molding
*
operation by hot pressing of a block of foam according to the invention in order to form a polarizer using waveguide technology.
Figure 5 shows an axial cross-section of the polarizer obtained with the process according to the invention.
Figure 6 shows an axial cross-section of a microwave antenna produced with the process according to the .invention.
Figure 2 shows a preform of substantially conical shape from a block of synthetic foam 3 . This preform is conformed in a mold • 4 by hot pressing in order to form a corrugated horn 5 shown in figure 3. Here, the synthetic foam is a polymethacrylimide foam marketed .under the name of "ROHACELL HF%. The corrugations • &.; of•the horn are formed on the external surface of the block of foam 3 by thermoforming. The surface of the conformed block of foam 3 is then metallized in order to form the corrugated horn. The heavy line 7 on the external surface of the block of foam 3 represents the metallic coating of the block of foam. Figure 4 shows a preform of substantially cylindrical shape from a block of synthetic foam 3'. This preform is conformed in a mold 4' by hot pressing in order to form a polarizer 8 shown in figure 5. The conformation consists in the formation of two radial slots 9, 10 in the block of foam 3' that are symmetrical in an axial plane of the cylindrical block of foam. The surface of the conformed block of
foam 3' is then metallized as shown by the heavy line 11.
Figure 6 now shows a microwave antenna produced using waveguide technology according to the process of the invention. The antenna comprises a corrugated horn such as 5 that is excited by a circular waveguide polarizer such as 8 together with an impedance adapter 13. The antenna is formed as a single piece from a thermoformed block of foam. More particularly, on the external surface of a first section of the block of foam of conical shape, the corrugations of the horn have been formed by thermof orming. On the external surface of a second section of the block of foam of cylindrical shape, a circular groove 12 has been formed by thermof orming in order to form the
- impedance adapter. On the external surface of a third~ section of the block of foam of cylindrical shape, two radial slots have been formed by thermoforming in order to form the polarizer. The thermof orming of the:; three sections of the block of foam is carried out in a single step using a single mold.
In the case where a polymethacrylimide foam is used, the preform is preheated to around 150°C in order to
,r.s;Qfiteen>; . it for insertion into the "mold. Once the,*> preform has been inserted into the mold, a suitable temperature profile is applied, for both the temperature rise phase up to 180°C and for the temperature decrease, with a progressive application of pressure. The removal from the mold is effected at room temperature or slightly higher.
Subsequently, the surfaces of the sections of the block of foam are metallized by projection of a metallic paint of the silver type or derivative thereof, or alternatively using a brush or by dipping into a metallic bath as indicated above. The metallic coating on the surface of the block of foam (depicted with hatching) is represented by the heavy line in figure 6.

1. A manufacturing process for a microwave corrugated-horn
antenna (5) using waveguide technology, characterized in that it
comprises the steps of:
conforming a block of foam (3) of synthetic material into a horn,
- forming corrugations (6) on whole external surface of
the foam block by deforming such external surface, and
metallizing the external surface of the foam block provided with corrugations.
2. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in claim 1, wherein the corrugations of the horn are formed by hot pressing of the block of foam in a mold (4).
3. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in claim 1 or 2, wherein the metallization of the surface of the block of foam is carried out by projection or using a brush, or alternatively by dipping.
4. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in one of claims 1 to 3, wherein two radial slots (9, 10) are formed in a cylindrical section of the block of foam by thermoforming and the surface of this section of the block of foam is metallized in order to form a waveguide polarizer.

5. The manufacturing process for a microwave corrugated-horn antenna (5) as claimed in one of claims 1 to 4, wherein a circular groove (12) is formed in another section of the block of foam by thermoforming and the surface of this other section of the block of foam is metallized in order to form an impedance adapter.
6. A microwave corrugated-horn antenna (5) using waveguide technology characterized in that formed from a block of synthetic foam (3) having, on its external surface, corrugations (6) obtained by deformation of said surface, said corrugations (6) being metallized.
7. The microwave corrugated-horn antenna (5) as claimed in claim 6, wherein it comprises, in addition, a waveguide polarizer (8) formed by two radial slots (9, 10) formed in a first cylindrical section of the block of foam (3), this first section being metallized.
8. The microwave corrugated-horn antenna (5) as claimed in either of claims 6 and 7, wherein it comprises, in addition, an impedance adapter (13) formed by a circular groove (12) formed in a second section of the block of foam, this second section being metallized.

Documents:

1084-DELNP-2005-Abstract-(19-02-2008).pdf

1084-delnp-2005-abstract.pdf

1084-delnp-2005-claims-(01-07-2008).pdf

1084-DELNP-2005-Claims-(19-02-2008).pdf

1084-delnp-2005-claims.pdf

1084-DELNP-2005-Correspondence-Others-(19-02-2008).pdf

1084-delnp-2005-correspondence-others.pdf

1084-delnp-2005-description (complete)-01-07-2008.pdf

1084-delnp-2005-description (complete)-19-02-2008.pdf

1084-delnp-2005-description (complete).pdf

1084-DELNP-2005-Drawings-(19-02-2008).pdf

1084-delnp-2005-drawings.pdf

1084-delnp-2005-form-1.pdf

1084-delnp-2005-form-18.pdf

1084-delnp-2005-form-2.pdf

1084-DELNP-2005-Form-3-(19-02-2008).pdf

1084-delnp-2005-form-3.pdf

1084-delnp-2005-form-5.pdf

1084-DELNP-2005-GPA-(19-02-2008).pdf

1084-delnp-2005-gpa.pdf

1084-DELNP-2005-Petition-137-(19-02-2008).pdf

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Patent Number

222097

Indian Patent Application Number

1084/DELNP/2005

PG Journal Number

32/2008

Publication Date

08-Aug-2008

Grant Date

21-Jul-2008

Date of Filing

18-Mar-2005

Name of Patentee

THOMSON LICENSING S.A.

Applicant Address

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

Inventors:

#	Inventor's Name	Inventor's Address
1	ALI LOUZIR	6 RUE DE LA GODMONDIERE, F-35000 RENNES, FRANCE
2	DOMINIQUE LO HINE TONG	44 RUE JEANNE COUPLAN, F-35700 RENNES, FRANCE
3	FLORENT AVERTY	24 BOULEVARD SOLFERINO, F-35000 RENNES, FRANCE
4	CHRISTIAN PERSON	5 IMPASSE DES HORTENSIAS, F-29280 LOCMARIA PLOUZANE, FRANCE
5	JEAN PHILIPPE COUPEZ	RESIDENCE EDEN PARK, 260 RUE JEAN SALIOU, F-29480 LE RELECQ KERHUON, FRANCE

PCT International Classification Number

H01Q

PCT International Application Number

PCT/FR2003/050071

PCT International Filing date

2003-10-01

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	02/12411	2002-10-07	France