US4080601A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radio frequency filter network having bandpass and bandreject characteristics
Assignee: Wacom Products Inc
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Filing: 1976-04-01
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Granted: 1978-03-21
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Expires: 1996-04-01
Abstract
Abstract In a filter network a common coupling element provides input of radio frequency energy to both an odd quarter wavelength resonant cavity and a variable reactance isolating the coupling element from ground. The resonant cavity presents an open circuit to a selected pass frequency and the variable reactance shunts energy to ground at a selected reject frequency. In a duplexer for radio transmitter and receiver, a filter network attaches to the transmission line between transmitter and antenna junction; the cavity is tuned to the transmitter carrier; the variable reactance is tuned to the receiver frequency. A similar filter network attaches to the transmission line between receiver and the same antenna junction; the resonant cavity is tuned to receiver frequency and the variable reactance is tuned to the transmitter carrier. The networks are spaced one quarter wavelength from the antenna junction.
Inventors
- 👤 Lloyd C. Alcorn, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:31
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/213; H01P1/2133
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
136 words
A filter network for connection to a transmission line of radio frequency energy, said filter network designed to selectively pass one frequency and selectively reject another frequency comprisng in combination: an odd quarter wavelength resonator including an outer shell connected to ground and an internal coupling loop, said coupling loop beng ungrounded and having a first point of contact at said outer shell for connection to said transmission line, said resonator being tuned to resonate and present generally maximum impedance at the frequency to be passed; and variable reactance means connected in series relationship between said ground and a second point of contact of said ungrounded, internal coupling loop at said outer shell, said reactance means being tuned to maximize shunting there-through to said ground of said radio frequency energy at the frequency to be rejected.
Claim 2
Dependent Claim
136 words
A filter network for connection to a transmission line of radio frequency energy, said filter network designed to selectively pass one frequency and selectively reject another frequency comprisng in combination: an odd quarter wavelength resonator including an outer shell connected to ground and an internal coupling loop, said coupling loop beng ungrounded and having a first point of contact at said outer shell for connection to said transmission line, said resonator being tuned to resonate and present generally maximum impedance at the frequency to be passed; and variable reactance means connected in series relationship between said ground and a second point of contact of said ungrounded, internal coupling loop at said outer shell, said reactance means being tuned to maximize shunting there-through to said ground of said radio frequency energy at the frequency to be rejected.
Claim 3
Dependent Claim
14 words
A filter network of claim 1 wherein said transmission line comprises a coaxial cable.
Claim 4
Dependent Claim
18 words
A filter network of claim 1 wherein the reactance means comprises a variable length of coaxial transmission line.
Claim 5
Dependent Claim
14 words
A filter network of claim 1 wherein said resonator comprises a high-Q selective cavity.
Claim 6
Dependent Claim
28 words
A filter network of claim 1 wherein an extension of said internal coupling loop protrudes externally of said outer shell and said second point of contact is external.
Claim 7
Dependent Claim
162 words
A duplexer network for operation of a radio transmitter and receiver comprising: a common antenna; a first transmission line connecting said antenna to said transmitter; a second transmission line connecting said antenna to said receiver; a first filter network of claim 1 connected to said first transmission line at a first distance from said connection of said first transmission line to said antenna, said first filter network being tuned to pass the carrier frequency of said transmitter and shunt off the operating frequency of said receiver, said first distance being one quarter wavelength of the operating frequency of said receiver; and a second filter network of claim 1 connected to said second transmission line at a second distance from said connection of said second transmission line to said antenna, said second filter network being tuned to pass the receiver operating frequency and shunt off the transmitter carrier frequency, said second distance being one quarter wavelength of the carrier frequency of said transmitter.
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) | 1981-03-20 | 1981-09-19 | 1982-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-20 | 1985-09-19 | 1986-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-20 | 1989-09-19 | 1990-03-21 | $7700.00 | Window Closed / Lapsed |