US4218683A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Range focus lens
Assignee: Plessey Inc
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Filing: 1978-08-25
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Granted: 1980-08-19
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Expires: 1998-08-25
Abstract
Abstract Various aspects of electro-magnetic testing are facilitated by inserting a foamed plastic dielectric lens at a particular position between a particular radiating source and the test aperture. The lens is constructed according to electro-optic formulae and the radiation wavelength to produce a plane wave of uniform phase. To control extraneous energy contributed by reflections from the flat face of the lens, this surface is provided with two layers of high-performance absorber material. The amplitude characteristics in the test region are controlled by appropriate selection of the source antenna. Radiation-absorbent material is also provided to eliminate amplitude distortion. This makes possible testing under far-field conditions in test cells of modest size, which has heretofore been possible only with elaborate parabolic reflectors. Weather restrictions on use of free-space ranges, the sheer size of such ranges, and security problems attendant on their use, are all thus avoided. The lens can be manufactured from any plastic having a suitable dielectric constant, by either blowing the plastic in a suitable mold, or by machining from a preformed foam block. The absorber layers are loaded with conductive carbon to provide desired insertion loss and attached to the flat face.
Inventors
- 👤 Leland H. Hemming
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:51
CPC Classifications
H; H01; H01Q; H01Q19/00; H01Q19/02; H01Q19/021; G; G01; G01R; G01R29/00; G01R29/08; G01R29/10; G01R29/105; H01Q15/00; H01Q15/02; H01Q15/08; H01Q19/005; H01Q19/022; H01Q19/06; H01Q19/062; G01S; G01S7/00; G01S7/02; G01S7/40; G01S7/4052; G01S7/4082; G01S7/4086
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
56 words
A dielectric lens for converting a spherical wavefront of electromagnetic radiation to a plane wave comprising: a planoconvex lens formed of uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5; a radiation-absorbing covering on the planar surface only of said lens; said covering being adapted to substantially prevent reflection of radiation.
Claim 2
Dependent Claim
56 words
A dielectric lens for converting a spherical wavefront of electromagnetic radiation to a plane wave comprising: a planoconvex lens formed of uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5; a radiation-absorbing covering on the planar surface only of said lens; said covering being adapted to substantially prevent reflection of radiation.
Claim 3
Dependent Claim
36 words
The dielectric lens as claimed in claim 1, wherein said covering comprises a pair of pyramidally-cut foamed plastic sheets loaded with conductive carbon and mounted back-to-back, with peaks in one sheet adjacent valleys in the other.
Claim 4
Dependent Claim
21 words
The dielectric lens as claimed in claim 2, wherein said covering is 1.1 to 1.5 times larger than said planar surface.
Claim 5
Dependent Claim
43 words
The dielectric lens as claimed in claim 2, and additionally comprising a third pyramidally-cut foamed plastic sheet having its flat surface affixed to said planar lens surface, and its pyramidally cut surface affixed to one of said pair of sheets in mating relation.
Claim 6
Dependent Claim
20 words
The dielectric lens as claimed in claim 4, wherein said third sheet is detachably secured to said pair of sheets.
Claim 7
Dependent Claim
23 words
The dielectric lens as claimed in claim 1, wherein said radiation-absorbing covering is adapted to provide between 5 and 30 dB of suppression.
Claim 8
Dependent Claim
56 words
A dielectric lens for converting a spherical wavefront of electromagnetic radiation to a plane wave comprising: a miniscus lens formed of uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5; a radiation-absorbing layer adjacent the concave surface only of said lens; said covering being adapted to substantially prevent reflection of radiation.
Claim 9
Dependent Claim
56 words
A dielectric lens for converting a spherical wavefront of electromagnetic radiation to a plane wave comprising: a miniscus lens formed of uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5; a radiation-absorbing layer adjacent the concave surface only of said lens; said covering being adapted to substantially prevent reflection of radiation.
Claim 10
Dependent Claim
36 words
The dielectric lens as claimed in claim 7, wherein said layer comprises a pair of pyramidally-cut foamed plastic sheets loaded with conductive carbon and mounted back-to-back, with peaks in one sheet adjacent valleys in the other.
Claim 11
Dependent Claim
21 words
The dielectric lens as claimed in claim 8, wherein said layer is 1.1 to 1.5 times larger than said lens diameter.
Claim 12
Dependent Claim
47 words
The dielectric lens as claimed in claim 8, and additionally comprising a third pyramidally-cut foamed plastic sheet having a convex surface affixed to and mating with said planar lens concave surface, and its pyramidally cut surface affixed to one of said pair of sheets in mating relation.
Claim 13
Dependent Claim
20 words
The dielectric lens as claimed in claim 10, wherein said third sheet is detachably secured to said pair of sheets.
Claim 14
Dependent Claim
23 words
The dielectric lens as claimed in claim 7, wherein said radiation-absorbing covering is adapted to provide between 5 and 30 dB of suppression.
Claim 15
Dependent Claim
87 words
A test fixture for an electromagnetic test range comprising: a movable supporting structure; an electromagnetic radiation antenna mounted on said structure; a dielectric plane wave lens mounted on said structure in a fixed, spaced relation to said antenna, said lens being formed of a uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5; a radiation-absorbing layer adjacent only the side of said lens adapted to face a test object; and radiation-absorbing material surrounding the radiation path between said antenna and said lens.
Claim 16
Dependent Claim
87 words
A test fixture for an electromagnetic test range comprising: a movable supporting structure; an electromagnetic radiation antenna mounted on said structure; a dielectric plane wave lens mounted on said structure in a fixed, spaced relation to said antenna, said lens being formed of a uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5; a radiation-absorbing layer adjacent only the side of said lens adapted to face a test object; and radiation-absorbing material surrounding the radiation path between said antenna and said lens.
Claim 17
Dependent Claim
28 words
The test fixture as claimed in claim 13, wherein said antenna is a transmitting antenna, and said lens is oriented to transmit a planar wavefront into free space.
Claim 18
Dependent Claim
24 words
The test fixture as claimed in claim 14, wherein the distance between said antenna and said lens equals the focal length of said lens.
Claim 19
Dependent Claim
28 words
The test fixture as claimed in claim 14, wherein said antenna is a receiving antenna, and said lens is oriented to transmit a planar wavefront to said antenna.
Claim 20
Dependent Claim
23 words
The test fixture as claimed in claim 13, wherein radiation-absorbing material on said lens side provides between 5 and 30 dB of suppression.
Claim 21
Dependent Claim
97 words
An electromagnetic test range comprising: a source of electromagnetic radiation; a test device; a dielectric plane wave lens between said source and said device, said lens being formed of a uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5 and positioned to direct a plane wave to said device; first radiation-absorbing means surrounding the path between said source and said device for minimizing reflections and amplitude distortion; and second radiation-absorbing means adjacent said lens on the side of said test device only, said second absorbing means adapted to substantially eliminate wave re-reflections.
Claim 22
Dependent Claim
97 words
An electromagnetic test range comprising: a source of electromagnetic radiation; a test device; a dielectric plane wave lens between said source and said device, said lens being formed of a uniformly foamed plastic having a dielectric constant in the range of 1.05 to 1.5 and positioned to direct a plane wave to said device; first radiation-absorbing means surrounding the path between said source and said device for minimizing reflections and amplitude distortion; and second radiation-absorbing means adjacent said lens on the side of said test device only, said second absorbing means adapted to substantially eliminate wave re-reflections.
Claim 23
Dependent Claim
25 words
The electromagnetic test range as claimed in claim 18, wherein the distance between said source and said lens equals the focal length of said lens.
Claim 24
Dependent Claim
38 words
The electromagnetic test range as claimed in claim 18, wherein said surrounding means comprise an enclosure for said source, test device and lens, said enclosure having interior surfaces adapted to absorb electromagnetic radiation and forming an anechoic chamber.
Claim 25
Dependent Claim
17 words
The electromagnetic test range as claimed in claim 18, wherein said test device is a receiving antenna.
Claim 26
Dependent Claim
23 words
The electromagnetic test range as claimed in claim 21, wherein the diameter of said lens is larger than the size of said antenna.
Claim 27
Dependent Claim
35 words
The electromagnetic test range as claimed in claim 18, wherein said second absorbing means is 1.1 to 1.5 times larger than said lens, and is adapted to provide between 5 and 30 dB of suppression.
Claim 28
Independent Claim
124 words
The method of testing electromagnetic devices under far-field conditions on an antenna range comprising: generating a test signal having a spherical wavefront at a first point, employing interception means to intercept said signal at a second point and convert same to a planar wavefront; intercepting the converted wavefront with the antenna to be tested; providing first radiation-absorbing means adjacent the path of said signal adapted to minimize amplitude distortion and reflection; said interception means comprising a plane wave lens constructed of a uniformly-foamed plastic having a dielectric constant in the range of 1.05 to 1.5; providing second radiation-absorbing means only on the side of said lens facing said tested antenna to absorb signals reflected from said antenna; and measuring predetermined properties of said device.
Claim 29
Independent Claim
124 words
The method of testing electromagnetic devices under far-field conditions on an antenna range comprising: generating a test signal having a spherical wavefront at a first point, employing interception means to intercept said signal at a second point and convert same to a planar wavefront; intercepting the converted wavefront with the antenna to be tested; providing first radiation-absorbing means adjacent the path of said signal adapted to minimize amplitude distortion and reflection; said interception means comprising a plane wave lens constructed of a uniformly-foamed plastic having a dielectric constant in the range of 1.05 to 1.5; providing second radiation-absorbing means only on the side of said lens facing said tested antenna to absorb signals reflected from said antenna; and measuring predetermined properties of said device.
Claim 30
Dependent Claim
23 words
The method as claimed in claim 24, wherein the distance between said first and second points equals the focal length of said lens.
Claim 31
Dependent Claim
32 words
The method as claimed in claim 24, wherein said second radiation-absorbing means is near the planar side of said lens and is adapted to provide between 5 and 30 dB of suppression.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-08-19 | 1984-02-18 | 1984-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-08-19 | 1988-02-18 | 1988-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-08-19 | 1992-02-18 | 1992-08-19 | $7700.00 | Window Closed / Lapsed |