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US3673500A
Expired / Lapsed
US
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Cyclotron resonance frequency-selective limiter using inhomogeneous rf magnetic field
Assignee: Westinghouse Electric Corp
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Filing: 1970-06-09
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Granted: 1972-06-27
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Expires: 1990-06-09
Abstract
Abstract A tunable limiter is disclosed which utilizes a semiconductor containing an excess of free electrons and having a cyclotron resonance line which is inhomogeneously broadened. The semiconductor is exposed to a static magnetic field and spatially inhomogeous RF electric field at the cyclotron resonance frequency, within a waveguide cavity. The RF electric field is derived from the incoming signal, which contains information as well as possible jamming signals. By virtue of the thermoelectric-cyclotron-resonance effect, power from signals exceeding a saturation level set by the intensity of the RF field causes saturation of the limiter, but only at the frequency of those signals. This provides limiting of intense jamming signals without disturbing information signals at nearby frequencies.
Inventors
- 👤 Dickron Mergerian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:12
CPC Classifications
H; H04; H04K; H04K3/00; H04K3/20; H04K3/22; H04K3/224; H04K3/228; G; G01; G01S; G01S7/00; G01S7/02; G01S7/36; H03; H03G; H03G11/00; H03G11/006
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
115 words
A tunable limiter for received signals, comprising: a semiconductor sample containing an excess of free electrons and having a cyclotron resonance line which can be broadened by an inhomogeneous magnetic field, means for subjecting said semiconductor to a static magnetic field, means for subjecting said semiconductor sample to a spatially inhomogeneous RF electric field derived from RF signals, means for simultaneously subjecting said semiconductor sample simultaneously to a static magnetic field in crossed relation to said RF magnetic field and of such magnitude as to establish a selected cyclotron resonance frequency to thereby obtain preferential absorption determined by said free electrons, over the specific narrow frequency bands occupied by the signals exceeding said saturation level.
Claim 2
Dependent Claim
115 words
A tunable limiter for received signals, comprising: a semiconductor sample containing an excess of free electrons and having a cyclotron resonance line which can be broadened by an inhomogeneous magnetic field, means for subjecting said semiconductor to a static magnetic field, means for subjecting said semiconductor sample to a spatially inhomogeneous RF electric field derived from RF signals, means for simultaneously subjecting said semiconductor sample simultaneously to a static magnetic field in crossed relation to said RF magnetic field and of such magnitude as to establish a selected cyclotron resonance frequency to thereby obtain preferential absorption determined by said free electrons, over the specific narrow frequency bands occupied by the signals exceeding said saturation level.
Claim 3
Dependent Claim
22 words
The limiter of claim 1, wherein: said static magnetic field is variable in magnitude to tune the center frequency of the limiter.
Claim 4
Dependent Claim
22 words
The limiter of claim 1, wherein: said semiconductor is positioned in a microwave cavity within which all of said fields are present.
Claim 5
Dependent Claim
18 words
The limiter of claim 1, wherein: said semiconductor comprises germanium having approximately 1017 free electrons per cubic centimeter.
Claim 6
Dependent Claim
19 words
The limiter of claim 1, wherein: said semiconductor comprises indium antimonide having approximately 1017 free electrons per cubic centimeter.
Claim 7
Dependent Claim
30 words
The limiter of claim 1, further including: means for subjecting said semiconductor to a separate RF electric field of preselected intensity to establish said saturation level at a desired value.
Claim 8
Independent Claim
98 words
A method of limiting jamming signals in a RF receiver, comprising: producing a static magnetic field in a waveguide while simultaneously applying a spatially inhomogeneous RF magnetic field orthogonal to said static magnetic field in response to RF signals in said waveguide, and disposing a semiconductor in said waveguide for simultaneous subjection to both of said fields, said semiconductor having an excess of free electrons, for preferential absorption of power by said semiconductor from said electric field at specific discrete frequencies of signals exceeding a saturation level established by said free electrons, for preferential limiting at said frequencies.
Claim 9
Independent Claim
98 words
A method of limiting jamming signals in a RF receiver, comprising: producing a static magnetic field in a waveguide while simultaneously applying a spatially inhomogeneous RF magnetic field orthogonal to said static magnetic field in response to RF signals in said waveguide, and disposing a semiconductor in said waveguide for simultaneous subjection to both of said fields, said semiconductor having an excess of free electrons, for preferential absorption of power by said semiconductor from said electric field at specific discrete frequencies of signals exceeding a saturation level established by said free electrons, for preferential limiting at said frequencies.
Claim 10
Dependent Claim
32 words
The method according to claim 7 further including: varying the magnitude of said static magnetic field to vary the center frequency of the band of frequencies over which said limiting is achieved.
Claim 11
Dependent Claim
27 words
The method according to claim 8 further including: varying the collision time of said free electrons to vary said band of frequencies over which limiting is achieved.
Claim 12
Dependent Claim
30 words
The method according to claim 7 further including: applying a separate RF electric field to said semiconductor to set the saturation level to which received signals are to be limited.
References Cited (Backward Citations)
US3327247A
Cited
US3506933A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |