US4799034A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Varactor tunable coupled transmission line band reject filter
Assignee: Northrop Grumman Guidance and Electronics Co Inc
•
Filing: 1987-10-26
•
Granted: 1989-01-17
•
Expires: 2007-10-26
Abstract
Abstract A tunable coupled transmission line band reject filter for use in the microwave frequency range includes a coupled transmission line having first and second line sections. Each line section has an input end and an output end. A transmission line exhibits a natural notch at a particular frequency. A first varactor is coupled between the input ends of the first and second sections. A second varactor is coupled between the output ends of the first and second sections. A D.C. bias voltage across the varactor diodes controls the center frequency of the resulting notch filter.
Inventors
- 👤 Lawrence H. Silverman
- 👤 Randy Teague
- 👤 Richard Kaminsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:26
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/201; H01P1/203; H01P1/20327; H01P1/20354; H01P1/20363
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
100 words
A tunable coupled transmission line band reject filter for use in the microwave frequency range comprising: a coupled transmission line having first and second line sections, each line section having an input end and an output end, said transmission line exhibiting a natural notch at a particular frequency; a first varactor coupled between the input ends of said first and second sections; a second varactor coupled between the output ends of said first and second sections; and means for biasing said first and second varactors to change the capacitance thereof, thereby changing the frequency at which said natural notch occurs.
Claim 2
Dependent Claim
100 words
A tunable coupled transmission line band reject filter for use in the microwave frequency range comprising: a coupled transmission line having first and second line sections, each line section having an input end and an output end, said transmission line exhibiting a natural notch at a particular frequency; a first varactor coupled between the input ends of said first and second sections; a second varactor coupled between the output ends of said first and second sections; and means for biasing said first and second varactors to change the capacitance thereof, thereby changing the frequency at which said natural notch occurs.
Claim 3
Dependent Claim
30 words
The filter of claim 1 further comprising: a first choke coupling said biasing means to said first varactor; and a second choke coupling said biasing means to said second varactor.
Claim 4
Dependent Claim
13 words
The filter of claim 1 wherein said transmission line is a suspended line.
Claim 5
Dependent Claim
92 words
The filter of claim 3 wherein said suspended line comprises: a dielectric substrate having a top surface and a bottom surface; said first line section located on the top surface of said substrate; said second line section located on the bottom surface of said substrate is parallel with said first line section and substantially in registration therewith; means for mounting said first varactor adjacent the input ends of said first and second line sections; and means for mounting said second varactor adjacent the output ends of said first and second line sections.
Claim 6
Dependent Claim
117 words
A tunable band reject filter for use at microwave frequencies comprising: a coupled transmission line having first and second straight-line sections coupled to each other and a natural band reject notch centered at a particular frequency; first conductor means electrically connected to said first line section for inputting an input signal to said first line section; varactor means coupled between said first and second line sections and adapted to receive a bias voltage for varying the center frequency of said notch, the change in center frequency being dependent on the magnitude of the bias voltage; and second conductor means electrically connected to said second line section for outputting the input signal after coupling through said transmission line.
Claim 7
Dependent Claim
117 words
A tunable band reject filter for use at microwave frequencies comprising: a coupled transmission line having first and second straight-line sections coupled to each other and a natural band reject notch centered at a particular frequency; first conductor means electrically connected to said first line section for inputting an input signal to said first line section; varactor means coupled between said first and second line sections and adapted to receive a bias voltage for varying the center frequency of said notch, the change in center frequency being dependent on the magnitude of the bias voltage; and second conductor means electrically connected to said second line section for outputting the input signal after coupling through said transmission line.
Claim 8
Dependent Claim
21 words
The filter of claim 5 wherein said first and second line sections are supported on opposite surfaces of a flat dielectric.
Claim 9
Dependent Claim
17 words
The filter of claim 5 wherein said first and second line sections are fabricated using microstrip techniques.
Claim 10
Dependent Claim
17 words
The filter of claim 5 wherein said first and second line sections are fabricated using stripline techniques.
Claim 11
Dependent Claim
18 words
The filter of claim 5 further comprising choke means for coupling said bias voltage to said varactor means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-17 | 1992-07-18 | 1993-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-17 | 1996-07-18 | 1997-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-17 | 2000-07-18 | 2001-01-17 | $7700.00 | Window Closed / Lapsed |