EP0140598B1 - Horn-reflector microwave antennas with absorber lined conical feed - Google Patents
Horn-reflector microwave antennas with absorber lined conical feed Download PDFInfo
- Publication number
- EP0140598B1 EP0140598B1 EP19840306759 EP84306759A EP0140598B1 EP 0140598 B1 EP0140598 B1 EP 0140598B1 EP 19840306759 EP19840306759 EP 19840306759 EP 84306759 A EP84306759 A EP 84306759A EP 0140598 B1 EP0140598 B1 EP 0140598B1
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- EP
- European Patent Office
- Prior art keywords
- horn
- conical
- absorber
- reflector
- plane
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000006096 absorbing agent Substances 0.000 title claims description 63
- 239000000463 material Substances 0.000 claims description 34
- 238000009826 distribution Methods 0.000 claims description 7
- 230000005855 radiation Effects 0.000 claims description 3
- 239000002184 metal Substances 0.000 description 12
- 230000008901 benefit Effects 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000000593 degrading effect Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000219000 Populus Species 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000005574 cross-species transmission Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
- H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
- H01Q19/12—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave
- H01Q19/13—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave the primary radiating source being a single radiating element, e.g. a dipole, a slot, a waveguide termination
- H01Q19/132—Horn reflector antennas; Off-set feeding
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/001—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems for modifying the directional characteristic of an aerial
Definitions
- the present invention relates generally to microwave antennas and, more particularly, to reflector-type microwave antennas having conical feeds.
- Conical feeds for reflector-type microwave antennas have been known for many years. For example, a 1963 article in The Bell System Technical Journal describes the selection of a conical horn-reflector antenna for use in satellite communication ground station (Hines et al, "The Electrical Characteristics of The Conical Horn-Reflector Antenna", The Bell System Technical Journal, July 1963, pp. 1187-1211). A conical horn-reflector antenna is also described in Daw- son U.S. Patent No. 3,550,142, issued December 22, 1970. Conical feed horns have also been used with large parabolic dish antennas.
- a related object of this invention is to provide an improved conical feed which is capable of bringing the RPE's in both the E and H-planes even closer together.
- a conical horn-reflector antenna comprising the combination of a paraboloidal reflector forming a paraboloidal reflecting surface for transmitting and receiving microwave energy, and a conical feed horn for guiding microwave energy from the focus of said paraboloidal reflecting surface to said reflector, the small end of the horn being located near and with its apex coincident with the focal point of the paraboloidal reflector, the lower portion of said horn having a smooth metallic interior wall defining a conical surface which, when projected onto the reflector, is intercepted by the paraboloidal reflecting surface thereof, the upper portion of said horn being lined with absorber on at least those portions of the interior wall which affect the E-plane field distribution so as to cause the radiation pattern envelope width in the E-plane to approach that in the H-plane, characterised by said absorber having its thickness located outside of the projection of said conical surface defined by said lower portion of said horn and having its exposed surface lying substantially on said conical surface projection.
- the exposed surface of the absorber may be smooth or profiled in the form of multiple pyramids or convoluted cones.
- a conical horn-reflector microwave antenna having a conical section 10 for guiding microwave signals to a parabolic reflector plate 11. From the reflector plate 11, the microwave signals are transmitted through an aperture 12 formed in the front of a cylindrical section 13 which is attached to both the conical section 10 and the reflector plate 11 to form a completely enclosed integral antenna structure.
- the parabolic reflector plate 11 is a section of a paraboloid representing a surface of revolution formed by rotating a parabolic curve about an axis which extends through the vertex and the focus of the parabolic curve.
- any microwaves originating at the focus of such a parabolic surface will be reflected by the plate 11 in planar wavefronts perpendicular to the axis 14.
- the conical section 10 of the illustrative antenna is arranged so that its apex coincides with the focus of the paraboloid, and so that the axis 15 of the conical section is perpendicular to the axis of the paraboloid.
- the cylindrical section 13 serves as a shield which prevents the reflector plate 11 from producing interfering side and back signals and also helps to capture some spillover energy launched from the conical section feed.
- the conical section 10, the reflector plate 11, and the cylindrical shield 13 are usually formed of conductive metal (though it is only essential that the reflector plate 11 have a metallic surface).
- the top of the reflector plate 11 is covered by a panel 20 attached to the cylindrical shield 13.
- a radome 21 also covers the aperture 12 at the front of the antenna to provide further protection from the weather.
- the inside surface of the cylindrical shield 12 is covered with an absorber material 22 to absorb stray signals so that they do not degrade the RPE.
- absorber materials are well known in the art, and typically comprise a conductive material such as metal or carbon dispersed throughout a dielectric material having a surface in the form of multiple pyramids or convoluted cones.
- the lower end portion of the inside surface of the conical feed horn is formed by a smooth metal wall, and the balance of the inside surface of the horn is formed by a layer of absorber material, the surfaces of the metal wall and the absorber material defining a single continuous conical surface.
- the bottom section 10a of the conical feed horn 10 has a smooth inside metal surface.
- the balance of the inside surface of the conical horn 10 is formed by an absorber material 30, with the innermost surfaces of the metal section 10a and the absorber material 30 defining a single continuous conical surface.
- the metal wall adjoining the lower horn section 10a forms an outwardly extending shoulder 10b at the top of the section 10a, and then extends upwardly along the outside surface of the absorber 30.
- the metal wall forms a second outwardly extending shoulder 10d to accommodate the greater thickness of the absorber material 22 which lines the shield portion of the antenna above the conical feed horn.
- This recessed arrangement of the absorber material 30 permits further narrowing of the E-plane RPE and/or reductions in the gain drop of the antenna as compared with the structure shown in the aforementioned European Patent Publication No. 66455A. More specifically, for a given gain drop, the structure of the present invention permits the absober material to be extended farther down into the throat of the conical feed horn 10, thereby further narrowing the E-plane RPE.
- the metal surface of the section 10 can be extended farther up from the bottom of the conical feed horn so that the narrowness of the E-plane RPE is essentially the same as that produced by the structure described in European Patent Publication No. 66455A, but at the same time reducing the gain drop relative to that of the structure described in said copending Application.
- the lining 30 may be formed from conventional absorber materials, one example of which is AAP-ML-73 absorber made by Advanced Absorber Products Inc., 4 Poplar Street, Amesbury, Maine, U.S.A.
- This absorber material has a flat surface, as illustrated in Fig. 4 (in contrast to the pyramidal or conical surface of the absorber used in the shield), and is about 3/8 inches (9.5 mm) thick.
- the absorber material may be secured to the metal walls of the antenna by means of an adhesive.
- the exemplary absorber material identified above it is preferably cut into a multiplicity of relatively small pads which can be butted against each other to form a continuous layer of absorber material over the curvilinear surface to which it is applied. This multiplicity of pads is illustrated by the grid patterns shown in Figs. 1-3.
- the absorber material 30 is provided only on the two diametrically opposed regions of the interior walls of the conical horn 10 that affect the patterns of the antenna in the horizontal plane.
- the only significant patterns of the antenna are those taken in the horizontal plane, which is the Y-Z plane in Fig. 3. That is, for a horizontally polarized signal, the Y-Z plane is the E-plane, and the X-Z plane is the H-plane; for a vertically polarized signal, the Y-Z plane is the H-plane, and the X-Z plane is the E-plane.
- the portions of the conical feed horn 10 that principally affect the E-plane RPE (of a horizontally polarized signal) are the left and right hand walls of the horn through which the X-Y plane extends.
- the absorber material 30 can be limited to diametrically opposed regions 40 of the inside surface of the feed horn. Restricting the absorber material in this manner reduces the cost of the antenna by reducing both the amount of absorber material required and the labour required to instal the absorber lining within the conical horn.
- the absorber can be recessed (flush mounted) into the horn wall in the two regions 40 so as to maintain a single continuous conical surface on the inside of the horn 10.
- the metal wall can form the entire conical surface, as in the structure described in the aforementioned European Patent Publication No. 66455A, and the absorber material 30 applied only to the limited regions 40 on the inner surface thereof.
- the absorber material 30 within the conical section 10 causes the field distribution within the cone to taper off more sharply adjacent to the inside surface of the cone, due to the fact that the wall impedance of the absorber lining tends to force the perpendicular E field to zero. Furthermore, it does this while abstracting only a small fraction of the passing microwave energy propagating through the cone.
- E8 (r, 8, 0) and E0 (r, 6, 0) be the polar and azimuthal components of electric field (with the origin at the apex of the cone, and 8 and 0 the polar and azimuthal angles, respectively) then, it can be shown that they can be mathematically expressed as:
- An actual absorber has E differing from the no absorber case of 1.84 and the perfect absorber case of 2.39, with a hybridicity factor, Rs, neither zero (no absorber) or unity (perfect absorber). In general both will be complex with finite loss in the absorber.
- the RPE improvements described above can be achieved over a relatively wide frequency band.
- the improvements described above for the antenna illustrated in Figs. 1-3 can be realised over the common carrier frequency bands commonly referred to as the 4 GHz, 6 GHz and 11 GHz bands.
- Absorber materials are generally characterised by three parameters: thickness, dielectric constant, and loss tangent.
- the absorber used in the present invention must have a thickness and loss tangent sufficient to suppress undesirable surface (slow) waves.
- Such surface waves can be readily generated at the transition from the metallic portion of the inside surface of the cone wall to the absober-lined portion of the cone wall, but these waves are attenuated by the absorber so that they do not interfere with the desired field pattern of the energy striking the reflector plate 11.
- the end result is that all the improvements described above are attained without producing any undesirable distortion in the field patterns.
- the narrowing E-plane effect can, in fact, be achieved with zero loss tangent material, but with no loss the surfaces waves are not attenuated and the operating bandwidth is reduced. Consequently, it is preferred to use an absorber material with some loss.
- the invention has been described with particular reference to a horn-reflector antenna, it will be appreciated that the invention can also be used to advantage in a primary feed horn for a dish-type antenna. Indeed, in the latter application the substantially equal main beam widths in the E and H planes provided by the absorber lined feed horn are particularly advantageous because they provide symmetrical illumination of the parabolic dish. The consequent approximately equal second patterns with their reduced sidelobes, over a wide bandwidth, and with negligible gain loss, are also important in this primary feed horn application.
Landscapes
- Aerials With Secondary Devices (AREA)
- Waveguide Aerials (AREA)
Description
- The present invention relates generally to microwave antennas and, more particularly, to reflector-type microwave antennas having conical feeds.
- Conical feeds for reflector-type microwave antennas have been known for many years. For example, a 1963 article in The Bell System Technical Journal describes the selection of a conical horn-reflector antenna for use in satellite communication ground station (Hines et al, "The Electrical Characteristics of The Conical Horn-Reflector Antenna", The Bell System Technical Journal, July 1963, pp. 1187-1211). A conical horn-reflector antenna is also described in Daw- son U.S. Patent No. 3,550,142, issued December 22, 1970. Conical feed horns have also been used with large parabolic dish antennas.
- One of the problems with a smooth-walled conical horn reflector antenna is that its radiation pattern envelope (hereinafter referred to as the "RPE") in the E-plane is substantially wider than its RPE in the H-plane. When used in terrestrial communication systems, the wide beamwidth in the E-plane can cause interference with signals from other antennas. Also, when a smooth-walled conical horn is used as the primary feed for a parabolic dish antenna, its different beamwidths in the E and H-planes make it difficult to achieve symmetrical illumination of the parabolic dish.
- In European Patent Publication No. 66455A there is described an improved horn-reflector antenna having a lining of absorber material within the conical feed horn. That antenna produces narrower E-plane RPE's, thereby bringing the E-plane and H-plane RPE's closer together, without significantly degrading other performance characteristics of the antenna.
- It is a primary object of the present invention to provide an economical and effective way to achieve further narrowing of the E-plane RPE of a horn-reflector antenna having a conical feed, without significantly degrading the H-plane RPE or any other performance characteristic of the antenna. In this connection, a related object of this invention is to provide an improved conical feed which is capable of bringing the RPE's in both the E and H-planes even closer together.
- It is another important object of this invention to provide an improved horn-deflector antenna which introduces only a small gain drop into the microwave system in which it is used.
- It is yet another object of this invention to provide such an improved horn-reflector antenna which can be efficiently and economically fabricated.
- Other objects and advantages of the invention will be apparent from the following detailed description and the accompanying drawings.
- According to the present invention there is provided a conical horn-reflector antenna comprising the combination of a paraboloidal reflector forming a paraboloidal reflecting surface for transmitting and receiving microwave energy, and a conical feed horn for guiding microwave energy from the focus of said paraboloidal reflecting surface to said reflector, the small end of the horn being located near and with its apex coincident with the focal point of the paraboloidal reflector, the lower portion of said horn having a smooth metallic interior wall defining a conical surface which, when projected onto the reflector, is intercepted by the paraboloidal reflecting surface thereof, the upper portion of said horn being lined with absorber on at least those portions of the interior wall which affect the E-plane field distribution so as to cause the radiation pattern envelope width in the E-plane to approach that in the H-plane, characterised by said absorber having its thickness located outside of the projection of said conical surface defined by said lower portion of said horn and having its exposed surface lying substantially on said conical surface projection.
- The exposed surface of the absorber may be smooth or profiled in the form of multiple pyramids or convoluted cones.
- Fig. 1 is a front elevation, partially in section, of a horn-reflector antenna embodying the present invention;
- Fig. 2 is a vertical section taken along line 2-2 in Fig. 1;
- Fig. 3 is a perspective view of the antenna illustrated in Figs. 1 and 2 with various reference lines superimposed therein;
- Fig. 4 is an enlarged end view of one of the pads of absorber material used to form an absorber lining in the conical section of the antenna of Figs. 1-3;
- Fig. 5 is a vertical section, similar to Fig. 2 of a modified horn-reflector antenna embodying the present invention; and
- Fig. 6 is a section taken generally along line 6-6 in Fig. 5.
- Turning now to the drawings and referring first to Figs. 1 and 2, there is illustrated a conical horn-reflector microwave antenna having a
conical section 10 for guiding microwave signals to a parabolic reflector plate 11. From the reflector plate 11, the microwave signals are transmitted through anaperture 12 formed in the front of acylindrical section 13 which is attached to both theconical section 10 and the reflector plate 11 to form a completely enclosed integral antenna structure. - The parabolic reflector plate 11 is a section of a paraboloid representing a surface of revolution formed by rotating a parabolic curve about an axis which extends through the vertex and the focus of the parabolic curve. As is well known, any microwaves originating at the focus of such a parabolic surface will be reflected by the plate 11 in planar wavefronts perpendicular to the axis 14. Thus, the
conical section 10 of the illustrative antenna is arranged so that its apex coincides with the focus of the paraboloid, and so that the axis 15 of the conical section is perpendicular to the axis of the paraboloid. With this geometry, a diverging spherical wave emanating from theconical section 10 and striking the reflector plate 11 is reflected as a plane wave which passes through theaperture 12 and is perpendicular to the axis 14. Thecylindrical section 13 serves as a shield which prevents the reflector plate 11 from producing interfering side and back signals and also helps to capture some spillover energy launched from the conical section feed. It will be appreciated that theconical section 10, the reflector plate 11, and thecylindrical shield 13 are usually formed of conductive metal (though it is only essential that the reflector plate 11 have a metallic surface). - To protect the interior of the antenna from both the weather and stray signals, the top of the reflector plate 11 is covered by a
panel 20 attached to thecylindrical shield 13. Aradome 21 also covers theaperture 12 at the front of the antenna to provide further protection from the weather. The inside surface of thecylindrical shield 12 is covered with anabsorber material 22 to absorb stray signals so that they do not degrade the RPE. Such absorber materials are well known in the art, and typically comprise a conductive material such as metal or carbon dispersed throughout a dielectric material having a surface in the form of multiple pyramids or convoluted cones. - In keeping with the present invention, the lower end portion of the inside surface of the conical feed horn is formed by a smooth metal wall, and the balance of the inside surface of the horn is formed by a layer of absorber material, the surfaces of the metal wall and the absorber material defining a single continuous conical surface. Thus, in the illustrative embodiment of Figs. 1-3, the bottom section 10a of the
conical feed horn 10 has a smooth inside metal surface. The balance of the inside surface of theconical horn 10 is formed by anabsorber material 30, with the innermost surfaces of the metal section 10a and theabsorber material 30 defining a single continuous conical surface. To support theabsorber material 30 in the desired position and shape, the metal wall adjoining the lower horn section 10a forms an outwardly extending shoulder 10b at the top of the section 10a, and then extends upwardly along the outside surface of theabsorber 30. This forms a continuous conical metal shell 10c along the entire length of theabsorber material 30. At the top of theabsorber material 30, the metal wall forms a second outwardly extendingshoulder 10d to accommodate the greater thickness of theabsorber material 22 which lines the shield portion of the antenna above the conical feed horn. - This recessed arrangement of the
absorber material 30 permits further narrowing of the E-plane RPE and/or reductions in the gain drop of the antenna as compared with the structure shown in the aforementioned European Patent Publication No. 66455A. More specifically, for a given gain drop, the structure of the present invention permits the absober material to be extended farther down into the throat of theconical feed horn 10, thereby further narrowing the E-plane RPE. On the other hand, for a given RPE (in other words, if it is desired to minimise the gain drop of the antenna), the metal surface of thesection 10 can be extended farther up from the bottom of the conical feed horn so that the narrowness of the E-plane RPE is essentially the same as that produced by the structure described in European Patent Publication No. 66455A, but at the same time reducing the gain drop relative to that of the structure described in said copending Application. - The
lining 30 may be formed from conventional absorber materials, one example of which is AAP-ML-73 absorber made by Advanced Absorber Products Inc., 4 Poplar Street, Amesbury, Maine, U.S.A. This absorber material has a flat surface, as illustrated in Fig. 4 (in contrast to the pyramidal or conical surface of the absorber used in the shield), and is about 3/8 inches (9.5 mm) thick. The absorber material may be secured to the metal walls of the antenna by means of an adhesive. When the exemplary absorber material identified above is employed, it is preferably cut into a multiplicity of relatively small pads which can be butted against each other to form a continuous layer of absorber material over the curvilinear surface to which it is applied. This multiplicity of pads is illustrated by the grid patterns shown in Figs. 1-3. - In accordance with a further aspect of the present invention, the
absorber material 30 is provided only on the two diametrically opposed regions of the interior walls of theconical horn 10 that affect the patterns of the antenna in the horizontal plane. In terrestrial communication systems, the only significant patterns of the antenna are those taken in the horizontal plane, which is the Y-Z plane in Fig. 3. That is, for a horizontally polarized signal, the Y-Z plane is the E-plane, and the X-Z plane is the H-plane; for a vertically polarized signal, the Y-Z plane is the H-plane, and the X-Z plane is the E-plane. The portions of theconical feed horn 10 that principally affect the E-plane RPE (of a horizontally polarized signal) are the left and right hand walls of the horn through which the X-Y plane extends. Thus, as illustrated in Fig. 5, theabsorber material 30 can be limited to diametrically opposedregions 40 of the inside surface of the feed horn. Restricting the absorber material in this manner reduces the cost of the antenna by reducing both the amount of absorber material required and the labour required to instal the absorber lining within the conical horn. - When the
absorber material 30 does not extend around the entire circumference of thehorn 10, the absorber can be recessed (flush mounted) into the horn wall in the tworegions 40 so as to maintain a single continuous conical surface on the inside of thehorn 10. Alternatively, the metal wall can form the entire conical surface, as in the structure described in the aforementioned European Patent Publication No. 66455A, and theabsorber material 30 applied only to thelimited regions 40 on the inner surface thereof. These constructions will not offer the full advantages of the recessed absorber arrangement illustrated in Figs. 1-3, but they reduce the manufacturing cost of the antenna. - As described in the aforementioned European Patent Publication No. 66455A, the
absorber material 30 within theconical section 10 causes the field distribution within the cone to taper off more sharply adjacent to the inside surface of the cone, due to the fact that the wall impedance of the absorber lining tends to force the perpendicular E field to zero. Furthermore, it does this while abstracting only a small fraction of the passing microwave energy propagating through the cone. - There is a substantial difference in the taper or drop-off of the field distributions in the E and H-planes in the absence of the
absorber material 30. With theabsorber material 30 in the horn, the E-plane field distribution tapers off much more sharply, approaching that of the H-plane field, while there is only a slight degradation in the H-plane taper which brings it even closer to the E-plane field. In the theoretically ideal situation, the profile of the E-plane field distribution would coincide with that of the H-plane. In actual practice, this theoretically ideal condition can only be approximated, though the approximation is closer with the present invention than with the structure described in the aforementioned European Patent Publication No. 66455A. - Mathematically, the operation of the feed horn can be characterised as follows. If we let E8 (r, 8, 0) and E0 (r, 6, 0) be the polar and azimuthal components of electric field (with the origin at the apex of the cone, and 8 and 0 the polar and azimuthal angles, respectively) then, it can be shown that they can be mathematically expressed as:
-
- One then notes that the fields are uniquely known for the range of 0≤θ≤αo and 0≤0̸≤360° if the parameters E (the Eigen value) and Rs (the spherical hybridicity factor) are known. These parameters are uniquely determined by the nature of the conical wall material.
-
- For the perfect absorber case (also a corrugated horn with quarter wave teeth) it can be shown that E=2.39, Rs=+1, thus giving
- An actual absorber has E differing from the no absorber case of 1.84 and the perfect absorber case of 2.39, with a hybridicity factor, Rs, neither zero (no absorber) or unity (perfect absorber). In general both will be complex with finite loss in the absorber.
- The RPE improvements described above can be achieved over a relatively wide frequency band. For example, the improvements described above for the antenna illustrated in Figs. 1-3 can be realised over the common carrier frequency bands commonly referred to as the 4 GHz, 6 GHz and 11 GHz bands.
- Absorber materials are generally characterised by three parameters: thickness, dielectric constant, and loss tangent. The absorber used in the present invention must have a thickness and loss tangent sufficient to suppress undesirable surface (slow) waves. Such surface waves can be readily generated at the transition from the metallic portion of the inside surface of the cone wall to the absober-lined portion of the cone wall, but these waves are attenuated by the absorber so that they do not interfere with the desired field pattern of the energy striking the reflector plate 11. The end result is that all the improvements described above are attained without producing any undesirable distortion in the field patterns. The narrowing E-plane effect can, in fact, be achieved with zero loss tangent material, but with no loss the surfaces waves are not attenuated and the operating bandwidth is reduced. Consequently, it is preferred to use an absorber material with some loss.
- Although the invention has been described with particular reference to a horn-reflector antenna, it will be appreciated that the invention can also be used to advantage in a primary feed horn for a dish-type antenna. Indeed, in the latter application the substantially equal main beam widths in the E and H planes provided by the absorber lined feed horn are particularly advantageous because they provide symmetrical illumination of the parabolic dish. The consequent approximately equal second patterns with their reduced sidelobes, over a wide bandwidth, and with negligible gain loss, are also important in this primary feed horn application.
Claims (3)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US54239683A | 1983-10-17 | 1983-10-17 | |
US542396 | 1983-10-17 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0140598A1 EP0140598A1 (en) | 1985-05-08 |
EP0140598B1 true EP0140598B1 (en) | 1989-03-01 |
Family
ID=24163654
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19840306759 Expired EP0140598B1 (en) | 1983-10-17 | 1984-10-04 | Horn-reflector microwave antennas with absorber lined conical feed |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0140598B1 (en) |
JP (1) | JPH0626285B2 (en) |
BR (1) | BR8405210A (en) |
CA (1) | CA1223345A (en) |
DE (1) | DE3476950D1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5317328A (en) * | 1984-04-02 | 1994-05-31 | Gabriel Electronics Incorporated | Horn reflector antenna with absorber lined conical feed |
GB9006752D0 (en) * | 1990-03-27 | 1990-05-23 | Ferguson Ltd | Microwave antenna unit |
JP3006602U (en) * | 1994-07-13 | 1995-01-31 | ダイワ精工株式会社 | Double-bearing reel for fishing |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4012738A (en) * | 1961-01-31 | 1977-03-15 | The United States Of America As Represented By The Secretary Of The Navy | Combined layers in a microwave radiation absorber |
US3936837A (en) * | 1975-02-25 | 1976-02-03 | The United States Of America As Represented By The Secretary Of The Navy | Corrugated horn fed offset paraboloidal reflector |
FR2396435A1 (en) * | 1977-06-28 | 1979-01-26 | Thomson Csf | ANTENNA WITH LARGE ANGULAR DECOUPLING AND HIGH PURITY OF POLARIZATION |
US4282530A (en) * | 1979-12-26 | 1981-08-04 | Bell Telephone Laboratories, Incorporated | Cylindrical paraboloid weather cover for a horn reflector antenna with wave absorbing means |
US4410892A (en) * | 1981-05-26 | 1983-10-18 | Andrew Corporation | Reflector-type microwave antennas with absorber lined conical feed |
US4423422A (en) * | 1981-08-10 | 1983-12-27 | Andrew Corporation | Diagonal-conical horn-reflector antenna |
-
1984
- 1984-10-04 DE DE8484306759T patent/DE3476950D1/en not_active Expired
- 1984-10-04 EP EP19840306759 patent/EP0140598B1/en not_active Expired
- 1984-10-16 CA CA000465538A patent/CA1223345A/en not_active Expired
- 1984-10-16 BR BR8405210A patent/BR8405210A/en unknown
- 1984-10-16 JP JP59217212A patent/JPH0626285B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE3476950D1 (en) | 1989-04-06 |
JPH0626285B2 (en) | 1994-04-06 |
BR8405210A (en) | 1985-08-27 |
CA1223345A (en) | 1987-06-23 |
EP0140598A1 (en) | 1985-05-08 |
JPS60103804A (en) | 1985-06-08 |
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