Patent US1386888A successfully refreshed from Google Patents.
US3579154A
Expired / Lapsed
US
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Vhf filter having absorptive tuned section to eliminate narrow spurious passband
Assignee: Collins Radio Co
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Filing: 1969-04-23
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Granted: 1971-05-18
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Expires: 1989-04-23
Abstract
Abstract Disclosed is a very high frequency filter for use with a high frequency radio transmitter which prevents transmission of harmonics. The filter includes an absorptive filter which eliminates spurious passbands resulting from interaction of components. The absorptive filter includes highpass filters arranged in an L-network.
Inventors
- 👤 Glen W Deen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:47
CPC Classifications
H; H03; H03H; H03H7/00; H03H7/01; H03H7/075; H03H7/17; H03H7/1741; H03H7/1766; H03H7/1783; H03H7/1791
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
88 words
A harmonic filter for use with a radio transmitter comprising at least first and second lowpass filters having first and second cutoff frequencies, respectively, said second frequency being higher than said first frequency, an absorptive filter interconnecting said first and second lowpass filters, said absorptive filter including series and parallel portions forming an L-network which functions as an attenuator above a third frequency and which functions as an essentially lossless, lumpedelement section of transmission line below said third frequency, said third frequency being higher than said first frequency.
Claim 2
Dependent Claim
88 words
A harmonic filter for use with a radio transmitter comprising at least first and second lowpass filters having first and second cutoff frequencies, respectively, said second frequency being higher than said first frequency, an absorptive filter interconnecting said first and second lowpass filters, said absorptive filter including series and parallel portions forming an L-network which functions as an attenuator above a third frequency and which functions as an essentially lossless, lumpedelement section of transmission line below said third frequency, said third frequency being higher than said first frequency.
Claim 3
Dependent Claim
21 words
A harmonic filter as defined by claim 1 wherein said series portion and said parallel portion are each a highpass filter.
Claim 4
Dependent Claim
23 words
A harmonic filter as defined by claim 2 wherein the cutoff frequencies of said series portion and said parallel portion are the same.
Claim 5
Dependent Claim
18 words
A harmonic filter as defined by claim 3 wherein each highpass filter has the same number of poles.
Claim 6
Dependent Claim
30 words
A harmonic filter as defined by claim 2 wherein said series portion is synthesized for a constant current generator and said parallel portion is synthesized for a constant voltage generator.
Claim 7
Dependent Claim
55 words
A harmonic filter as defined by claim 5 wherein said parallel portion includes a load resistance equal to a multiple of the nominal impedance of the transmission line to which said filter is connected and said series portion includes a load resistance equal to said nominal impedance of said transmission line divided by said multiple.
Claim 8
Dependent Claim
74 words
A filter comprising first and second lowpass filters having first and second cutoff frequencies, respectively, a first highpass filter serially connecting said first and second lowpass filters, and a second highpass filter connected to said first highpass filter to from an L-network which functions as an attenuator above a third frequency and as an essentially lossless, lumped-element section of transmission line below said third frequency, said third frequency being higher than said first frequency.
Claim 9
Dependent Claim
74 words
A filter comprising first and second lowpass filters having first and second cutoff frequencies, respectively, a first highpass filter serially connecting said first and second lowpass filters, and a second highpass filter connected to said first highpass filter to from an L-network which functions as an attenuator above a third frequency and as an essentially lossless, lumped-element section of transmission line below said third frequency, said third frequency being higher than said first frequency.
Claim 10
Dependent Claim
33 words
A filter as defined by claim 7 wherein said first highpass filter includes a shunt indicator as an input element and said second highpass filter includes a series capacitor as an input element.
Claim 11
Dependent Claim
25 words
A filter as defined by claim 8 wherein said first and second highpass filters have the same cutoff frequency and an equal number of poles.
Claim 12
Dependent Claim
55 words
An absorptive filter comprising a series highpass filter and a shunt highpass filter cooperatively forming an L-network, each of said highpass filters comprising a ladder network of shunt inductors and series capacitors, said series highpass filter including a shunt inductor as an input element, and each highpass filter being terminated in a single resistive load.
Claim 13
Dependent Claim
55 words
An absorptive filter comprising a series highpass filter and a shunt highpass filter cooperatively forming an L-network, each of said highpass filters comprising a ladder network of shunt inductors and series capacitors, said series highpass filter including a shunt inductor as an input element, and each highpass filter being terminated in a single resistive load.
Claim 14
Dependent Claim
29 words
An absorptive filter as defined by claim 9 wherein said series highpass filter and said shunt highpass filter have the same cutoff frequency and an equal number of poles.
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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) | 1974-05-17 | 1974-11-16 | 1975-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-17 | 1978-11-16 | 1979-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-17 | 1982-11-16 | 1983-05-18 | $7700.00 | Window Closed / Lapsed |