US4786915A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Attenuation of microwave signals
Assignee: British Telecommunications PLC
•
Filing: 1988-03-16
•
Granted: 1988-11-22
•
Expires: 2008-03-16
Abstract
Abstract It is sometimes necessary to reduce the power of microwave transmissions, e.g. to avoid overloading a receiver or to reduce a transmitter's potential to cause interference. The invention reduces the power by inserting radiation absorbent material into the aperture of the antenna. In the preferred embodiment a membrane of absorbent plastics is stretched across the aperture of the dish reflector.
Inventors
- 👤 Norman E. Cartwright
- 👤 Miles E. Butcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:04
CPC Classifications
H; H01; H01Q; H01Q17/00; H01Q17/001
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
73 words
An antenna assembly having an r.f. aperture and which includes removable signal attenuation means which can be situated to cover substantially the entirety of said aperture, said signal attenuation means being adapted to partially absorb electromagnetic radiation so as to partially attenuate the signal by at least 1 dB when it is situated so as to obscure said aperture while permitting the remainder of such signal to pass onward toward a receiving site.
Claim 2
Dependent Claim
73 words
An antenna assembly having an r.f. aperture and which includes removable signal attenuation means which can be situated to cover substantially the entirety of said aperture, said signal attenuation means being adapted to partially absorb electromagnetic radiation so as to partially attenuate the signal by at least 1 dB when it is situated so as to obscure said aperture while permitting the remainder of such signal to pass onward toward a receiving site.
Claim 3
Dependent Claim
24 words
An antenna according to claim 1, wherein the signal attenuation means is adapted to attenuate the signal by between 5 dB and 30 dB.
Claim 4
Dependent Claim
36 words
An antenna according to either claim 1 or claim 2, wherein the antenna includes a reflective dish and the signal attenuation means takes the form of an absorptive sheet extending across the aperture of the dish.
Claim 5
Dependent Claim
18 words
An antenna according to claim 3, wherein the sheet comprises one or more layers of lossy dielectric material.
Claim 6
Dependent Claim
25 words
An antenna according to claim 3, wherein the sheet is resistive with a sheet resistance in the range of 10 to 1000 ohms per square.
Claim 7
Dependent Claim
23 words
An antenna according to either claim 1 or 2, wherein the signal attenuation means includes an array of resistively loaded dipole antenna elements.
Claim 8
Dependent Claim
22 words
An antenna according to claim 6, wherein the resistive loaded dipoles are implemented as conductive areas supported on an inert plastics sheet.
Claim 9
Dependent Claim
41 words
An attenuator, suitable for use in an antenna according to any one of the preceding claims, 1 or 2 which comprises attachment means carrying said signal attenuation means wherein said attachment means is adapted for removable attachment to said antenna assembly.
Claim 10
Dependent Claim
39 words
An attenuator according to claim 8, which takes the form of an absorptive sheet stretched across one end of a tubular support member the other end of which is adapted for attachment to the periphery of said antenna assembly.
Claim 11
Independent Claim
86 words
A method for controlling the amplitude of electromagnetic radiation of r.f. signals transmitted out of the r.f. aperture of an antenna assembly and onward toward a receiving site; said method comprising the step of: obscuring substantially all of said aperture with an r.f. absorptive sheet which absorbs a predetermined portion of at least 1 dB of said r.f. signals as they pass therethrough while permitting the remainder of said r.f. signals to pass onward, thereby controlling the amplitude of r.f. signals onward toward a receiving site.
Claim 12
Independent Claim
86 words
A method for controlling the amplitude of electromagnetic radiation of r.f. signals transmitted out of the r.f. aperture of an antenna assembly and onward toward a receiving site; said method comprising the step of: obscuring substantially all of said aperture with an r.f. absorptive sheet which absorbs a predetermined portion of at least 1 dB of said r.f. signals as they pass therethrough while permitting the remainder of said r.f. signals to pass onward, thereby controlling the amplitude of r.f. signals onward toward a receiving site.
References Cited (Backward Citations)
GB755011A
Cited
US3078461A
Cited
US3295131A
Cited
US3329958A
Cited
US3351947A
Cited
GB1326210A
Cited
US3740755A
Cited
GB1359266A
Cited
US3877920A
Cited
FR2269720A1
Cited
FR2304192A1
Cited
JPS5267945A
Cited
US4169268A
Cited
US4439768A
Cited
US4282530A
Cited
US4364053A
Cited
US4480256A
Cited
GB2120858A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-22 | 1992-05-23 | 1992-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-22 | 1996-05-23 | 1996-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-22 | 2000-05-23 | 2000-11-22 | $7700.00 | Window Closed / Lapsed |