US3656162A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Diplexer for radio communication
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1969-09-19
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Granted: 1972-04-11
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Expires: 1989-09-19
Abstract
Abstract A diplexer enabling radio transmitter and receiver to operate simultaneously or sequentially with the same antenna with closely spaced transmitter and receiver frequencies. The diplexer consists essentially of a low pass and notch filter in the transmitter circuit, a band pass filter in the receiving circuit and series coaxial cables of predetermined lengths in the transmitting and receiving circuits which are connected to a common antenna. The electrical length of the coaxial cable in the transmitting circuit is adjusted to be a high impedance to the receiver frequency, whereas the electrical length of the coaxial cable in the receiving circuit is adjusted to be a high impedance to the transmitter frequency. The low pass filter and the receiver band pass filter may be similar to those normally used in radio communication without diplexing. The notch filter is tuned to reject the wave energy generated by the transmitter at the receiver frequency.
Inventors
- 👤 Thomas Francis Mee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:11
CPC Classifications
H; H03; H03H; H03H7/00; H03H7/01; H03H7/17; H03H7/1741; H03H7/1791; H03H7/0115; H03H7/46; H03H2007/013
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
356 words
An improved diplexer circuit for connecting a radio transmitter and a radio receiver to a common antenna, wherein the transmitter operates at a first transmitter frequency and the receiver operates at a second receiver frequency within one percent of said first frequency, comprising: a low pass filter connected in series with said transmitter; a notch filter connected in series with said low pass filter tuned to reject noise generated by said transmitter at said second receiver frequency; said low pass filter and said notch filter integrally combined into first, second and third sections serially connected and housed within a common grounded enclosure; said low pass filter in said first, second and third sections each including a two terminal inductor serially connected to the other inductors in said other sections and a capacitor shunting the terminal of said inductor furthest from said transmitter to said grounded enclosure; said low pass filter in said first section including an additional capacitor shunting the terminal of the inductor nearest said transmitter to said grounded enclosure; said notch filter in said first, second and third sections each including a shunt capacitor having one electrode connected between the terminal of said first mentioned inductors furthest from said transmitter and said first mentioned capacitors, and further including second shunt capacitors and inductors connected in parallel between the second electrode of each of said first mentioned notch filter shunt capacitors and said grounded enclosure; a first coaxial cable connected in series between said notch filter and said common antenna, the length of said coaxial cable being a quarter wave length of said second receiver frequency such as to present a high impedance to said second receiver frequency; a band pass filter connected in series with said receiver; and a second coaxial cable connected in series between said band pass filter and said common antenna, the length of said second coaxial cable being a quarter wave length of said first transmitter frequency such as to present a high impedance to said first transmitter frequency; whereby said transmitter and receiver may be operated simultaneously in combination with said common antenna without interference and with negligible losses.
Claim 2
Dependent Claim
356 words
An improved diplexer circuit for connecting a radio transmitter and a radio receiver to a common antenna, wherein the transmitter operates at a first transmitter frequency and the receiver operates at a second receiver frequency within one percent of said first frequency, comprising: a low pass filter connected in series with said transmitter; a notch filter connected in series with said low pass filter tuned to reject noise generated by said transmitter at said second receiver frequency; said low pass filter and said notch filter integrally combined into first, second and third sections serially connected and housed within a common grounded enclosure; said low pass filter in said first, second and third sections each including a two terminal inductor serially connected to the other inductors in said other sections and a capacitor shunting the terminal of said inductor furthest from said transmitter to said grounded enclosure; said low pass filter in said first section including an additional capacitor shunting the terminal of the inductor nearest said transmitter to said grounded enclosure; said notch filter in said first, second and third sections each including a shunt capacitor having one electrode connected between the terminal of said first mentioned inductors furthest from said transmitter and said first mentioned capacitors, and further including second shunt capacitors and inductors connected in parallel between the second electrode of each of said first mentioned notch filter shunt capacitors and said grounded enclosure; a first coaxial cable connected in series between said notch filter and said common antenna, the length of said coaxial cable being a quarter wave length of said second receiver frequency such as to present a high impedance to said second receiver frequency; a band pass filter connected in series with said receiver; and a second coaxial cable connected in series between said band pass filter and said common antenna, the length of said second coaxial cable being a quarter wave length of said first transmitter frequency such as to present a high impedance to said first transmitter frequency; whereby said transmitter and receiver may be operated simultaneously in combination with said common antenna without interference and with negligible losses.
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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) | 1975-04-11 | 1975-10-11 | 1976-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-11 | 1979-10-11 | 1980-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-11 | 1983-10-11 | 1984-04-11 | $7700.00 | Window Closed / Lapsed |