Patent US3631346A successfully refreshed from Google Patents.
US3631346A
Expired / Lapsed
US
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Low self-noise radiometer system
Assignee: Unisys Corp
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Filing: 1970-02-02
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Granted: 1971-12-28
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Expires: 1990-02-02
Abstract
Abstract An improved microwave radiometer of the comparison type features elimination of broadband amplification through the employment of a modified high-frequency switch operating on the signal to be investigated in cooperation with a broadband low self-noise detector. The switch cyclically exposes the signal to be investigated and a reference signal to the detector at a rate of switching such that a strong component of the detected signal falls within the passband of a narrow band comparison and indicator system.
Inventors
- 👤 Robert F Riggs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:30
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/08; G01R29/0864; G01R29/0892
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
183 words
Radiometer apparatus including: antenna means, reference electrical noise source means, switch means having output port means and adapted alternately to connect said antenna means and said reference noise source means to said output port means, driver circuit means for operating said switch means at a predetermined frequency, semiconductor diode detector means having predetermined excess noise, shot noise, and thermal noise amplitude characteristics as a function of frequency, said thermal and shot noise amplitude characteristics being substantially constant as a function of frequency, said excess noise characteristic having a substantially hyperbolic characteristic as a function of frequency, said predetermined switching frequency being equal to or less than the frequency at which said excess noise is substantially equal to the sum of said thermal and shot noise, said semiconductor diode detector means being coupled to said switch output port means, amplifier means responsive to said semiconductor diode detector means, said amplifier means having a narrow passband including said predetermined switching frequency, phase sensitive detector means responsive to said amplifier means and to said driver circuit means, and utilization means responsive to said phase-sensitive detector means.
Claim 2
Dependent Claim
183 words
Radiometer apparatus including: antenna means, reference electrical noise source means, switch means having output port means and adapted alternately to connect said antenna means and said reference noise source means to said output port means, driver circuit means for operating said switch means at a predetermined frequency, semiconductor diode detector means having predetermined excess noise, shot noise, and thermal noise amplitude characteristics as a function of frequency, said thermal and shot noise amplitude characteristics being substantially constant as a function of frequency, said excess noise characteristic having a substantially hyperbolic characteristic as a function of frequency, said predetermined switching frequency being equal to or less than the frequency at which said excess noise is substantially equal to the sum of said thermal and shot noise, said semiconductor diode detector means being coupled to said switch output port means, amplifier means responsive to said semiconductor diode detector means, said amplifier means having a narrow passband including said predetermined switching frequency, phase sensitive detector means responsive to said amplifier means and to said driver circuit means, and utilization means responsive to said phase-sensitive detector means.
Claim 3
Dependent Claim
55 words
Apparatus as described in claim 1 wherein said predetermined switching frequency lies between that frequency at which said excess noise amplitude is substantially equal to the sum of said thermal and shot noise and that lower frequency at which said excess noise amplitude is substantially three times the sum of said thermal and shot noise.
Claim 4
Dependent Claim
30 words
Apparatus as described in claim 1 wherein said utilization means responsive to said phase sensitive detector means comprises: low-pass filter means, and display means responsive to said low-pass filter means.
Claim 5
Dependent Claim
30 words
Apparatus as described in claim 3 where said reference noise source means comprises at least one body of material having a predetermined electrical noise emitting characteristic at a predetermined temperature.
Claim 6
Dependent Claim
80 words
Apparatus as described in claim 4 wherein said switch means comprises: hollow wave transmission line means, said hollow wave transmission line means having at least one reentrant surface having a longitudinal slot therein, and resonant motive means for translating said reference noise source means through said slot means into and out of said hollow transmission line means for alternately and cyclically connecting said antenna means and said reference source means to said switch output port means at said predetermined frequency.
Claim 7
Dependent Claim
102 words
Apparatus as described in claim 3 wherein: said reference noise source means comprises a pair of bodies of material haviNg a predetermined electrical noise emitting characteristic at a predetermined temperature, and said switch means comprises: hollow wave transmission line means, said hollow wave transmission line means having opposed reentrant surfaces with opposed longitudinal slot means, resonant fork motive means for translating said reference noise bodies through said respective slot means into and out of said hollow wave transmission line means alternately and cyclically connecting said antenna means and said reference noise bodies to said switch output port means at said predetermined rate.
Claim 8
Dependent Claim
75 words
Apparatus as described in claim 6 wherein said resonant fork motive means is adapted cyclically to translate said bodies into and out of said ridged wave transmission line in phase synchronization so that, at one instant of time both bodies are substantially removed from said ridged transmission line interior and, at a succeeding instant of time, both bodies are moved into said ridged wave transmission line interior so that they are substantially in contacting relation.
References Cited (Backward Citations)
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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) | 1974-12-27 | 1975-06-28 | 1975-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-27 | 1979-06-28 | 1979-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-27 | 1983-06-28 | 1983-12-28 | $7700.00 | Window Closed / Lapsed |