US5838215A
Expired / Lapsed
US
⏱️ 0.0 years remaining
RF choke with a low Q core formed by sintering ferrous and ferric oxides
Assignee: Motorola Solutions Inc
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Filing: 1996-02-05
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Granted: 1998-11-17
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Expires: 2016-02-05
Abstract
Abstract A radio frequency (RF) choke inductor (102, 500, 600) includes a magnetic core (502, 602) which substantially dissipates RF and microwave signals. The magnetic core (502, 602) is sufficiently lossy to provide a substantially resistive impedance at RF and microwave frequencies. The magnetic core is formed by providing a homogeneous ferrite composition characterized by a mixture of ferrous ions and ferric ions (404), and then sintering the homogeneous ferrite composition in an inert gas atmosphere (412) to provide a rapid electron exchange reaction. A conductive wire is then wound about the magnetic core (414) to complete the choke inductor.
Inventors
- 👤 Wang-Chang Albert Gu
- 👤 E. S. Ramakrishnan
- 👤 Robert A. Burr
- 👤 Adam D. Moya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:02
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/34; H01F1/342; H01F1/344; C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; H01F17/00; H01F17/04; H01F41/00; H01F41/02; H01F41/0206; H01F41/0246
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
126 words
A radio frequency (RF) choke, comprising: a magnetic core having a quality factor (Q) less than 1 formed by: mixing at least two powdered iron oxide compounds, at least one compound being characterized by a ferrous valence state (Fe 2+ ) and at least one compound being characterized by a ferric valence state (Fe 3+ ), into a liquid media to form a homogeneous mixture; drying the homogeneous mixture at a temperature sufficient to remove the liquid media; compacting the dried homogeneous mixture into a form; and sintering the form in a non-oxidizing atmosphere sufficient to convert a portion of the Fe 3+ to Fe 2+ ; a wire wrapped about said magnetic core; and the magnetic core providing a substantially resistive impedance at RF frequencies.
Claim 2
Dependent Claim
126 words
A radio frequency (RF) choke, comprising: a magnetic core having a quality factor (Q) less than 1 formed by: mixing at least two powdered iron oxide compounds, at least one compound being characterized by a ferrous valence state (Fe 2+ ) and at least one compound being characterized by a ferric valence state (Fe 3+ ), into a liquid media to form a homogeneous mixture; drying the homogeneous mixture at a temperature sufficient to remove the liquid media; compacting the dried homogeneous mixture into a form; and sintering the form in a non-oxidizing atmosphere sufficient to convert a portion of the Fe 3+ to Fe 2+ ; a wire wrapped about said magnetic core; and the magnetic core providing a substantially resistive impedance at RF frequencies.
Claim 3
Dependent Claim
24 words
An RF choke as described in claim 1, wherein the at least two powdered iron oxide compounds includes Fe 3 O 4 and FeO.
Claim 4
Dependent Claim
28 words
An RF choke as described in claim 1, wherein the at least two powdered iron oxide compounds includes NiFe 2 O 4 and Fe 3 O 4 .
Claim 5
Dependent Claim
24 words
An RF choke as described in claim 1, wherein the at least two powdered iron oxide compounds includes NiFe 2 O 4 and FeO.
Claim 6
Dependent Claim
16 words
An RF choke as described in claim 1, wherein the liquid media comprises alcohol or water.
Claim 7
Dependent Claim
31 words
An RF choke as described in claim 1, wherein the step of mixing comprises mixing 50% by weight Fe 2 O 3 and 50% by weight Fe 3 O 4 .
Claim 8
Dependent Claim
24 words
An RF choke as described in claim 6, wherein the step of sintering takes place over a temperature range of approximately 1000-1300 degrees Celsius.
Claim 9
Dependent Claim
77 words
A radio frequency (RF) choke, comprising: a magnetic core having a qualitv factor (Q) less than 1 formed by: providing a homogeneous ferrite composition characterized by a mixture of ferrous ions and ferric ions; and sintering the homogeneous ferrite composition in an inert gas atmosphere sufficient to convert a portion of the ferric ions to ferrous ions; a conductive wire wrapped about said magnetic core; and said magnetic core providing a substantially resistive impedance at RF frequencies.
Claim 10
Dependent Claim
77 words
A radio frequency (RF) choke, comprising: a magnetic core having a qualitv factor (Q) less than 1 formed by: providing a homogeneous ferrite composition characterized by a mixture of ferrous ions and ferric ions; and sintering the homogeneous ferrite composition in an inert gas atmosphere sufficient to convert a portion of the ferric ions to ferrous ions; a conductive wire wrapped about said magnetic core; and said magnetic core providing a substantially resistive impedance at RF frequencies.
Claim 11
Dependent Claim
19 words
A radio frequency choke as described in claim 8, wherein the sintering provides for a rapid electron exchange reaction.
Claim 12
Dependent Claim
125 words
A radio frequency (RF) choke, comprising: a magnetic core having a quality factor (Q) less than 1 formed by: mixing at least two powdered iron oxide compounds into a liquid media to form a homogeneous mixture, said at least two powdered iron oxide compounds including at least one compound being characterized by a ferric valence state (Fe 3+ ); drying the homogeneous mixture at a temperature sufficient to remove the liquid media; compacting the dried homogeneous mixture into a shape; and sintering the shape in a non-oxidizing atmosphere sufficient to convert a portion of the Fe 3+ to a ferrous valence state (Fe2 + ); a conductive wire wrapped about said magnetic core; and said magnetic core providing a substantially resistive impedance at RF frequencies.
Claim 13
Dependent Claim
125 words
A radio frequency (RF) choke, comprising: a magnetic core having a quality factor (Q) less than 1 formed by: mixing at least two powdered iron oxide compounds into a liquid media to form a homogeneous mixture, said at least two powdered iron oxide compounds including at least one compound being characterized by a ferric valence state (Fe 3+ ); drying the homogeneous mixture at a temperature sufficient to remove the liquid media; compacting the dried homogeneous mixture into a shape; and sintering the shape in a non-oxidizing atmosphere sufficient to convert a portion of the Fe 3+ to a ferrous valence state (Fe2 + ); a conductive wire wrapped about said magnetic core; and said magnetic core providing a substantially resistive impedance at RF frequencies.
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| 3.5 Years (Year 4) | 2001-11-16 | 2002-05-18 | 2002-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-16 | 2006-05-18 | 2006-11-17 | $3760.00 | Window Closed / Lapsed |
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