CA1304155C - Lens/polarizer/radome - Google Patents
Lens/polarizer/radomeInfo
- Publication number
- CA1304155C CA1304155C CA000578627A CA578627A CA1304155C CA 1304155 C CA1304155 C CA 1304155C CA 000578627 A CA000578627 A CA 000578627A CA 578627 A CA578627 A CA 578627A CA 1304155 C CA1304155 C CA 1304155C
- Authority
- CA
- Canada
- Prior art keywords
- lens
- dielectric
- radio frequency
- aperture
- frequency energy
- Prior art date
- 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.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
- H01Q1/425—Housings not intimately mechanically associated with radiating elements, e.g. radome comprising a metallic grid
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/24—Polarising devices; Polarisation filters
- H01Q15/242—Polarisation converters
- H01Q15/244—Polarisation converters converting a linear polarised wave into a circular polarised wave
-
- 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
-
- 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
- H01Q19/06—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 refracting or diffracting devices, e.g. lens
Landscapes
- Aerials With Secondary Devices (AREA)
- Details Of Aerials (AREA)
Abstract
Abstract of the Disclosure An improved Lens/Polarizer/Radome system to modify the antenna pattern of an existing array antenna is shown to consist of a unitary assembly made up of a dielectric lens of appropriate shape, polarization determining means and absorbing means, such assembly being disposed to cover the aperture of the existing array antenna.
Description
~3q3 ~5~
LENS/POLARIZER/RADOME
Background of the Invention This invention pertains generally to directive antennas for radio frequency energy, and particularly to a Lens/Polarizer/Radome used in conjunc~ion with other types of antennas.
It is sometimes necessary to modify the shape of the antenna pattern of an array of antennas. In such case it would be standard practice to redesign the array to attain the desired modified antenna patternO However, such an approach could be relatively difficult and expensive to iinplement, especially if implementation were to require retrofitting an appreciable number of systems in the field.
~3~
62901~ S
Summar~_s~____e_~n _ ntion With the ore~oiny background in mind, it i~ a pr~mary object of ~his invention to provide a Lens~Polarizer/Radome ~hat may be easily attached to an existing array antenna to modify khe antenna pattern in a desired way without significantl~ affe~ting the other operating characteristies of such array antenna.
The foregoing and other objects of this lnverltlon are attained generally by providing a Lens/Polarizer/Radome incorporating an appropriately shaped dielectric lens alony with lo impedance matching and filtering structures, such Lens~Polarize.r/Radome being adapted for mounting on the existing array antenna to form a unitary structure.
More particularly, the presen~ invention pr~vides in an antenna system whereln the phase distribution of radio frequency energy across ~he aperture of an antenna array is ~o be changed from a first to a second phase distribution, khe improvemen~
comprising, (a) a dielectric lens formed o~ a material havin~ a dielectric constant greater ~han 2.0, such lens hav:Lny a ~lrst side with a ~urvature substantial:ly corresponcling to the curvature ~0 of the aperture of the antenna array and a second sld~ shaped to change the phase distrlbutian of radio frequency eneryy from the first to the second phase distrlbution; (b) impedance matching means overlying the first side o~ ~he dielectric lens and overlying the second side of the dielectric lens, such means being fabricated from a sheet of dielectric material having a dielec~ric constant substanti~lly equal to the square roo~ of the dielectric constant of the ma~erial o~ the dielectric lens and a thickness ~L3~ SS
6290~-7~5 substantially equal to one-quarter waveleng~h of the radlo frequency ener~iy; (c) absorbing means disposed around the periphery of the dielec~ric lens to control sidelobes and pattern nulls; and (d) supporting means ~or holdiny the lens, the lmpedance matching means and the absorbing means in the path of radio frequency energy passing to and from the aperture, ~he supporting means further being adaptecd to cause the first slde o~
the lens to be til~ed with reæpec~ to the aper~ure o~ the antenna array.
2a ~3~ 155i Brief Descr1ption of the _ wings For a more complete understanding of this invention, reference is now made to the following description of the accompanying drawings wherein:
FIG. 1 is an isometric drawing, partially cross-sectional, showing a Lens/Polarizer/Radome according to a preferred embodiment of this invention in place over an array antenna; and FIGS. 2 and 2A show a polarizer here contemplated.
~3~ 55;
Description of the Preferred Embo_iment Referring now to FIG. l, it may be seen that the elements of the contemplated Lens/Polarizer/Radome are mounted within a flan~ed rame 10 that is dimensioned to permit mountin~ in any convenient ~anner on the ace of an array antenna 12, here a linear array of sectoral horns ~not numbered). The elements of the contemplated Lens/Polari~er/Radome are a dielectric lens 13, a quarter-wave matching element 15, a polarization filter 17 and a polarizer l9. In addition, absorbers 21, 23, 24 are - ~ provided as shown.
The dielectric lens 13, here fabricated from polyethylene having a dielectric constant of approximately 2.3, is shaped to have a first surface 13a complementary in shape to the ends of the sectoral horns (not numbered). To put it another way, irst surface 13a is shaped to present nearly an equiphase surace to ields produced by the s0ctoral horns (not numberedj. A second surace 13b o the dielectric lens 13 is shaped to adjust the phase delay of rays passinq through the dlelectric lens 13 as required to attain a desired distribution across the aperture (not numbered) oE
the Lens/Polarizer/Radome. As is known, the phase delay at any point through the dielectric lens 13 is directly related to the thickness of the dielectric lens and to the square root of the dielectric constant .
, and inversely related to the wavelength of the electroma~netic energy being transmitted or received. In the illustrated example, where it is desired to increase the elevation angle of the up~er 3 dB point of the antenna pattern, i.e., increase the coverage in elevation, the cross-section of the dielectric lens 13 is shaped as shown. It is noted here that the first surface 13a of the dielectric lens 13 need not be concentric with the end of the sectoral horns (not numbered). As a matter of fact, in order to optimize elevation sidelobes it is here preferred that the dielectric lens 13 be rotated so that the upper end of the first surface 13a is sli~htly closer to the sectoral horn than the lower end of the first surface 13b.
The quarter-wave matching element 15 here is a sheet of foam rubber having a thickness of one-~uarter wavelength of electromagnetic energy passing throu~h the dielectric lens 13 in either direction. The dielectric constant of the foam rubber is equal approximately to the square root of the dielectric constant of the polyethylene of the dielectric lens 13. The quarter-wave matching element 15 is aEfixed with an electrically thin layer of R. F . transparent adhesive to the first and second surfaces 13a, 13b of the dielectric lens 13.
The polarization filter 17 and polarizer 19 here are ~3~5S
used to convert circularly polarized energy to linearly polarized enerqy and vice ~ersa and to compensate for changes in the cross-polarization component of the electromagnetic energy out of each sectoral horn (not numbered). As is known, such a cross-polarized component increases with non-principal plane angles. The polarization filter 17 is conventional, here being made up of parallel metal plates spaced at about 0.4 wavelengths at the upper end of the frequency band of interest and about 3/4 inches deep. The polarization filter 17, as shown, conforms with the polarizer 19. On transmission, then, only horizontally polarized energy is passed through the polarization filter 17 to the polarizer 19.
Referring now to FI~S. 2 and 2A, it will be seen that the polarizer 19 here consists of four sheets o dielectric material essentially transparent to the radio frequency energy passing throu~h the Lens/Polarizer/Radome, Before assembly a metallic meanderline l9a, l9b, l9c, l9d, l9e is formed on each one o the sheets in accordance with the table shown in FI(,. 2A. The meanderlines are oriented so that each is inclined at an angle of 45 to the horizontal. As a result, then, linearly polarized energy passing through the polarizer 19 is converted to circularly polarized energy. Because the polarizer 19 is a reciprocal device, circularly polarized enerqy passing through the ~olarizer 19 is converted to linearly polarized energy.
~30~9L55 To complete the contemplated Lens/Polarizer/Radome, absorbers 21, 23, 24 fabricated from any known absorbin~
material are affixed (as by cementing with an electrically thin layer of R~Fo transparent adhesive) to the perimeter of the dielectric lens 13 and adjacent areas. The absorbers 21, 23, 24 then are effective to prevent unwanted nulls in the antenna pattern and radiation from the ends of the dielectric lens 13. In addition, spaces between the elements of the just-described Lens/Polarizer/Radome preferably are filled with dielectrlc material (not shown) having a dielectric constant approximating 1Ø Such a filler then has no appreciable electrical effect, but rather serves only to make the Lens/Polarizer/Radome a unitary structure.
Having described apparatus that may be used to implement the contemplated invention, it will now be apparent to one of skill in the art that modifications may be made without departin~ from the inventive concept. It is felt, therefore, that this invention should not be restricted to its disclosed embodiment, but rather should be limited only by the spirit and scope of the appended claims.
'
LENS/POLARIZER/RADOME
Background of the Invention This invention pertains generally to directive antennas for radio frequency energy, and particularly to a Lens/Polarizer/Radome used in conjunc~ion with other types of antennas.
It is sometimes necessary to modify the shape of the antenna pattern of an array of antennas. In such case it would be standard practice to redesign the array to attain the desired modified antenna patternO However, such an approach could be relatively difficult and expensive to iinplement, especially if implementation were to require retrofitting an appreciable number of systems in the field.
~3~
62901~ S
Summar~_s~____e_~n _ ntion With the ore~oiny background in mind, it i~ a pr~mary object of ~his invention to provide a Lens~Polarizer/Radome ~hat may be easily attached to an existing array antenna to modify khe antenna pattern in a desired way without significantl~ affe~ting the other operating characteristies of such array antenna.
The foregoing and other objects of this lnverltlon are attained generally by providing a Lens/Polarizer/Radome incorporating an appropriately shaped dielectric lens alony with lo impedance matching and filtering structures, such Lens~Polarize.r/Radome being adapted for mounting on the existing array antenna to form a unitary structure.
More particularly, the presen~ invention pr~vides in an antenna system whereln the phase distribution of radio frequency energy across ~he aperture of an antenna array is ~o be changed from a first to a second phase distribution, khe improvemen~
comprising, (a) a dielectric lens formed o~ a material havin~ a dielectric constant greater ~han 2.0, such lens hav:Lny a ~lrst side with a ~urvature substantial:ly corresponcling to the curvature ~0 of the aperture of the antenna array and a second sld~ shaped to change the phase distrlbutian of radio frequency eneryy from the first to the second phase distrlbution; (b) impedance matching means overlying the first side o~ ~he dielectric lens and overlying the second side of the dielectric lens, such means being fabricated from a sheet of dielectric material having a dielec~ric constant substanti~lly equal to the square roo~ of the dielectric constant of the ma~erial o~ the dielectric lens and a thickness ~L3~ SS
6290~-7~5 substantially equal to one-quarter waveleng~h of the radlo frequency ener~iy; (c) absorbing means disposed around the periphery of the dielec~ric lens to control sidelobes and pattern nulls; and (d) supporting means ~or holdiny the lens, the lmpedance matching means and the absorbing means in the path of radio frequency energy passing to and from the aperture, ~he supporting means further being adaptecd to cause the first slde o~
the lens to be til~ed with reæpec~ to the aper~ure o~ the antenna array.
2a ~3~ 155i Brief Descr1ption of the _ wings For a more complete understanding of this invention, reference is now made to the following description of the accompanying drawings wherein:
FIG. 1 is an isometric drawing, partially cross-sectional, showing a Lens/Polarizer/Radome according to a preferred embodiment of this invention in place over an array antenna; and FIGS. 2 and 2A show a polarizer here contemplated.
~3~ 55;
Description of the Preferred Embo_iment Referring now to FIG. l, it may be seen that the elements of the contemplated Lens/Polarizer/Radome are mounted within a flan~ed rame 10 that is dimensioned to permit mountin~ in any convenient ~anner on the ace of an array antenna 12, here a linear array of sectoral horns ~not numbered). The elements of the contemplated Lens/Polari~er/Radome are a dielectric lens 13, a quarter-wave matching element 15, a polarization filter 17 and a polarizer l9. In addition, absorbers 21, 23, 24 are - ~ provided as shown.
The dielectric lens 13, here fabricated from polyethylene having a dielectric constant of approximately 2.3, is shaped to have a first surface 13a complementary in shape to the ends of the sectoral horns (not numbered). To put it another way, irst surface 13a is shaped to present nearly an equiphase surace to ields produced by the s0ctoral horns (not numberedj. A second surace 13b o the dielectric lens 13 is shaped to adjust the phase delay of rays passinq through the dlelectric lens 13 as required to attain a desired distribution across the aperture (not numbered) oE
the Lens/Polarizer/Radome. As is known, the phase delay at any point through the dielectric lens 13 is directly related to the thickness of the dielectric lens and to the square root of the dielectric constant .
, and inversely related to the wavelength of the electroma~netic energy being transmitted or received. In the illustrated example, where it is desired to increase the elevation angle of the up~er 3 dB point of the antenna pattern, i.e., increase the coverage in elevation, the cross-section of the dielectric lens 13 is shaped as shown. It is noted here that the first surface 13a of the dielectric lens 13 need not be concentric with the end of the sectoral horns (not numbered). As a matter of fact, in order to optimize elevation sidelobes it is here preferred that the dielectric lens 13 be rotated so that the upper end of the first surface 13a is sli~htly closer to the sectoral horn than the lower end of the first surface 13b.
The quarter-wave matching element 15 here is a sheet of foam rubber having a thickness of one-~uarter wavelength of electromagnetic energy passing throu~h the dielectric lens 13 in either direction. The dielectric constant of the foam rubber is equal approximately to the square root of the dielectric constant of the polyethylene of the dielectric lens 13. The quarter-wave matching element 15 is aEfixed with an electrically thin layer of R. F . transparent adhesive to the first and second surfaces 13a, 13b of the dielectric lens 13.
The polarization filter 17 and polarizer 19 here are ~3~5S
used to convert circularly polarized energy to linearly polarized enerqy and vice ~ersa and to compensate for changes in the cross-polarization component of the electromagnetic energy out of each sectoral horn (not numbered). As is known, such a cross-polarized component increases with non-principal plane angles. The polarization filter 17 is conventional, here being made up of parallel metal plates spaced at about 0.4 wavelengths at the upper end of the frequency band of interest and about 3/4 inches deep. The polarization filter 17, as shown, conforms with the polarizer 19. On transmission, then, only horizontally polarized energy is passed through the polarization filter 17 to the polarizer 19.
Referring now to FI~S. 2 and 2A, it will be seen that the polarizer 19 here consists of four sheets o dielectric material essentially transparent to the radio frequency energy passing throu~h the Lens/Polarizer/Radome, Before assembly a metallic meanderline l9a, l9b, l9c, l9d, l9e is formed on each one o the sheets in accordance with the table shown in FI(,. 2A. The meanderlines are oriented so that each is inclined at an angle of 45 to the horizontal. As a result, then, linearly polarized energy passing through the polarizer 19 is converted to circularly polarized energy. Because the polarizer 19 is a reciprocal device, circularly polarized enerqy passing through the ~olarizer 19 is converted to linearly polarized energy.
~30~9L55 To complete the contemplated Lens/Polarizer/Radome, absorbers 21, 23, 24 fabricated from any known absorbin~
material are affixed (as by cementing with an electrically thin layer of R~Fo transparent adhesive) to the perimeter of the dielectric lens 13 and adjacent areas. The absorbers 21, 23, 24 then are effective to prevent unwanted nulls in the antenna pattern and radiation from the ends of the dielectric lens 13. In addition, spaces between the elements of the just-described Lens/Polarizer/Radome preferably are filled with dielectrlc material (not shown) having a dielectric constant approximating 1Ø Such a filler then has no appreciable electrical effect, but rather serves only to make the Lens/Polarizer/Radome a unitary structure.
Having described apparatus that may be used to implement the contemplated invention, it will now be apparent to one of skill in the art that modifications may be made without departin~ from the inventive concept. It is felt, therefore, that this invention should not be restricted to its disclosed embodiment, but rather should be limited only by the spirit and scope of the appended claims.
'
Claims (2)
1. In an antenna system wherein the phase distribution of radio frequency energy across the aperture of an antenna array is to be changed from a first to a second phase distribution, the improvement comprising: (a) a dielectric lens formed of a material having a dielectric constant greater than 2.0, such lens having a first side with a curvature substantially corresponding to the curvature of the aperture of the antenna array and a second side shaped to change the phase distribution of radio frequency energy from the first to the second phase distribution; (b) impedance matching means overlying the first side of the dielectric lens and overlying the second side of the dielectric lens, such means being fabricated from a sheet of dielectric material having a dielectric constant substantially equal to the square root of the dielectric constant of the material of the dielectric lens and a thickness substantially equal to one-quarter wavelength of the radio frequency energy; (c) absorbing means disposed around the periphery of the dielectric lens to control sidelobes and pattern nulls; and (d) supporting means for holding the lens, the impedance matching means and the absorbing means in the path of radio frequency energy passing to and from the aperture, the supporting means further being adapted to cause the first side of the lens to be tilted with respect to the aperture of the antenna array.
2. The improvement as in claim 1 adapted to transmit or receive circularly polarized radio frequency energy comprising:
(a) a polarization filter disposed in the path of radio frequency energy passing to and from the lens, such filter being effective to limit the plane of polarization of such energy to a predetermined plane; and (b) a polarizer disposed over the polarization filter to convert the polarization of energy originating at the aperture/to/circular polarization.
(a) a polarization filter disposed in the path of radio frequency energy passing to and from the lens, such filter being effective to limit the plane of polarization of such energy to a predetermined plane; and (b) a polarizer disposed over the polarization filter to convert the polarization of energy originating at the aperture/to/circular polarization.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US103,778 | 1979-12-14 | ||
| US10377887A | 1987-10-02 | 1987-10-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1304155C true CA1304155C (en) | 1992-06-23 |
Family
ID=22296996
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000578627A Expired - Fee Related CA1304155C (en) | 1987-10-02 | 1988-09-28 | Lens/polarizer/radome |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0310414B1 (en) |
| AU (1) | AU618281B2 (en) |
| CA (1) | CA1304155C (en) |
| DE (1) | DE3889834T2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2729791B1 (en) * | 1988-06-14 | 1997-05-16 | Thomson Csf | DEVICE FOR REDUCING THE RADOME EFFECT WITH A BROADBAND ANTENNA WITH SURFACE RADIATION, AND REDUCING THE EQUIVALENT REFLECTING SURFACE OF THE ASSEMBLY |
| US5017939A (en) * | 1989-09-26 | 1991-05-21 | Hughes Aircraft Company | Two layer matching dielectrics for radomes and lenses for wide angles of incidence |
| US5086301A (en) * | 1990-01-10 | 1992-02-04 | Intelsat | Polarization converter application for accessing linearly polarized satellites with single- or dual-circularly polarized earth station antennas |
| IT1284301B1 (en) * | 1996-03-13 | 1998-05-18 | Space Engineering Spa | SINGLE OR DOUBLE REFLECTOR ANTENNA, SHAPED BEAMS, LINEAR POLARIZATION. |
| DE19714578C2 (en) * | 1997-04-09 | 1999-02-18 | Bosch Gmbh Robert | Radar system, especially for automotive applications |
| US20100074315A1 (en) * | 2008-09-24 | 2010-03-25 | Quellan, Inc. | Noise sampling detectors |
| CN107706526B (en) * | 2017-10-19 | 2024-04-05 | 西南交通大学 | High-power embedded polarization conversion radome |
| CN112234360B (en) * | 2020-09-17 | 2022-05-13 | 南京理工大学 | Dual-polarized transmission surface for controlling electrical characteristics by terminating filter circuit and design method thereof |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1267802A (en) * | 1968-03-25 | 1972-03-22 | Post Office | Improvements in or relating to front-fed aerial systems |
| GB1562866A (en) * | 1976-12-08 | 1980-03-19 | Gen Dynamics Corp | Antenn with performted metal plate angle filter |
| US4187507A (en) * | 1978-10-13 | 1980-02-05 | Sperry Rand Corporation | Multiple beam antenna array |
| US4220957A (en) * | 1979-06-01 | 1980-09-02 | General Electric Company | Dual frequency horn antenna system |
| DE3027094A1 (en) * | 1980-07-17 | 1982-02-04 | Siemens AG, 1000 Berlin und 8000 München | RE-POLARIZING DEVICE FOR GENERATING CIRCULAR POLARIZED ELECTROMAGNETIC WAVES |
| US4342034A (en) * | 1980-11-24 | 1982-07-27 | Raytheon Company | Radio frequency antenna with polarization changer and filter |
| FR2548466B1 (en) * | 1983-07-01 | 1985-10-25 | Radiotechnique Compelec | TRANSCEIVING DEVICE FOR PRESENCE DETECTION RADAR, AND METHOD FOR MAKING SAME |
| US4698639A (en) * | 1986-01-14 | 1987-10-06 | The Singer Company | Circularly polarized leaky waveguide doppler antenna |
| EP0280379A3 (en) * | 1987-02-27 | 1990-04-25 | Yoshihiko Sugio | Dielectric or magnetic medium loaded antenna |
-
1988
- 1988-09-28 CA CA000578627A patent/CA1304155C/en not_active Expired - Fee Related
- 1988-09-29 AU AU22923/88A patent/AU618281B2/en not_active Ceased
- 1988-09-30 DE DE19883889834 patent/DE3889834T2/en not_active Expired - Fee Related
- 1988-09-30 EP EP19880309094 patent/EP0310414B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0310414B1 (en) | 1994-06-01 |
| EP0310414A2 (en) | 1989-04-05 |
| DE3889834T2 (en) | 1995-01-05 |
| DE3889834D1 (en) | 1994-07-07 |
| AU618281B2 (en) | 1991-12-19 |
| AU2292388A (en) | 1989-04-06 |
| EP0310414A3 (en) | 1990-04-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |