US3750165A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intrusion detection apparatus having a high frequency diode oscillator-mixer element
Assignee: Johnson Service Co
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Filing: 1971-08-16
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Granted: 1973-07-31
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Expires: 1991-08-16
Abstract
Abstract An intrusion detector detects motion of a human intruder into a selected volumetric space. An oscillator-detector avalanche or impatt diode operating above 4GHz is mounted within an open ended conductive cavity of a coaxial line construction to define the active transmitting and mixing element of an oscillator-mixer establishing an RF field in the selected space and receiving the motion related signals via a common antenna. The diode is exposed to both the transmitted and the echo signal and produces a Doppler frequency output signal which is connected to an alarm. The system antenna and a load coupling impedance transformer are selected to optimize the magnitude of the Doppler motion signal response sensitivity. The microwave frequency oscillator signal is modulated by loosely coupling a general purpose diode to the open end of the oscillator-mixer open ended cavity.
Inventors
- 👤 J Bailey
- 👤 D Pridemore
- 👤 C Klein
- 👤 L Korta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:12
CPC Classifications
H; H03; H03B; H03B9/00; H03B9/12; H03B9/14; H03B9/145; G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/56; G08; G08B; G08B13/00; G08B13/22; G08B13/24; H03B2009/126; H03B7/00; H03B7/02; H03B7/06; H03B7/08
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
171 words
In a Doppler frequency generating oscillator-mixer apparatus, comprising a microwave cavity housing having an open-ended transmission cavity, a solid state two-terminal diode element having only two distinct states of conduction including one state defining a negative resistance characteristic, said one state being established by selected bias input potential, said diode element being mounted within the base of said cavity and defining a coaxial conductor with said cavity which is less than a quarter wave length, input bias means connected to said diode to bias the diode to said one state, load means including a common transmitting-receiving opening coupled to an antenna unit for transmitting and receiving microwave energy with respect to said cavity, said cavity impedance and said diode impedance and said load impedance being selected to provide for substantial mixing of the transmitted and received signals by said diode element and generating a significant Doppler frequency signal, and means connected to said solid state two-terminal device and responsive to the Doppler frequency signals generated by said solid state two-terminal device.
Claim 2
Dependent Claim
171 words
In a Doppler frequency generating oscillator-mixer apparatus, comprising a microwave cavity housing having an open-ended transmission cavity, a solid state two-terminal diode element having only two distinct states of conduction including one state defining a negative resistance characteristic, said one state being established by selected bias input potential, said diode element being mounted within the base of said cavity and defining a coaxial conductor with said cavity which is less than a quarter wave length, input bias means connected to said diode to bias the diode to said one state, load means including a common transmitting-receiving opening coupled to an antenna unit for transmitting and receiving microwave energy with respect to said cavity, said cavity impedance and said diode impedance and said load impedance being selected to provide for substantial mixing of the transmitted and received signals by said diode element and generating a significant Doppler frequency signal, and means connected to said solid state two-terminal device and responsive to the Doppler frequency signals generated by said solid state two-terminal device.
Claim 3
Dependent Claim
22 words
The apparatus oF claim 1 wherein said solid state two-terminal device is an avalanche diode of the impact avalanche transit time phenomena.
Claim 4
Dependent Claim
24 words
The microwave detection apparatus of claim 1 wherein the solid state two-terminal device is a diode operating with a bulk effect negative conduction characteristic.
Claim 5
Dependent Claim
37 words
The apparatus of claim 1 wherein said input bias means establishes an input power level creating optimum sensitivity with minimum output power and thereby optimizes the amplitude of the Doppler motion signal for a minimum input power.
Claim 6
Dependent Claim
61 words
The apparatus of claim 1 including a coupling iris to said oscillator microwave cavity, a reduced height wave guide cavity adjacent and coupled to said iris opening and including tuning means to vary the impedance of the reduced height wave guide and defining an impedance transformer for matching of the antenna''s load impedance to the impedance of the cavity and diode.
Claim 7
Dependent Claim
59 words
The apparatus of claim 5 wherein said tuning means includes a tuning screw selectively positioned into said reduced height wave guide to control the impedance of the impedance transformer, said tuning screw being spaced from the iris opening such that its impedance locus permits operation on a Smith Chart sensitivity contour characteristic in accordance with a desired sensitivity control.
Claim 8
Dependent Claim
42 words
The apparatus of claim 6 wherein said tuning screw is selected to establish a region of operation within the complete load impedance region in which a sensitivity contour, which establishes a Doppler motion signal, is less than maximum but avoids zero sensitivity.
Claim 9
Dependent Claim
37 words
The apparatus of claim 1 including a modulating diode, a coupling member connected to the modulating diode and disposed in the fringing field of the open transmission line cavity to couple the modulating diode to the cavity.
Claim 10
Dependent Claim
41 words
The apparatus of claim 8 wherein the coupling means is a small loop passed through a hole in the cavity wall immediately adjacent the open coaxial transmission line and a feed-through capacitor interconnecting the modulating diode to a modulating power supply.
Claim 11
Dependent Claim
195 words
In a solid state microwave cavity oscillator for generating and detecting motion within a microwave energy field, comprising a microwave cavity housing having an open-ended cavity, a microwave diode element secured within the lower end of the cavity, a center coaxial conductor connected to said diode and projecting outward of said cavity and terminating within said cavity to define a coaxial transmission line, an iris coupling opening to said cavity for transmitting and receiving of microwave energy, an impedance transformer with a reduced height wave guide adjacent said iris opening and having means coupled to said diode element to operate said diode element above 4 GHz, said input power level being established and selected to produce a diode impedance establishing less than maximum output power, said output power being selected in accordance with a significant increase in efficiency in the mixer characteristic of the diode element to thereby minimize the input power requirements while maintaining significant motion Doppler signal, said impedance transformer being adjusted to establish a Doppler motion sensitivity avoiding all zero sensitivity while establishing reliable continuous sensitive response to motion with significant variations in the load impedance so presented to the oscillator-mixer cavity.
Claim 12
Dependent Claim
195 words
In a solid state microwave cavity oscillator for generating and detecting motion within a microwave energy field, comprising a microwave cavity housing having an open-ended cavity, a microwave diode element secured within the lower end of the cavity, a center coaxial conductor connected to said diode and projecting outward of said cavity and terminating within said cavity to define a coaxial transmission line, an iris coupling opening to said cavity for transmitting and receiving of microwave energy, an impedance transformer with a reduced height wave guide adjacent said iris opening and having means coupled to said diode element to operate said diode element above 4 GHz, said input power level being established and selected to produce a diode impedance establishing less than maximum output power, said output power being selected in accordance with a significant increase in efficiency in the mixer characteristic of the diode element to thereby minimize the input power requirements while maintaining significant motion Doppler signal, said impedance transformer being adjusted to establish a Doppler motion sensitivity avoiding all zero sensitivity while establishing reliable continuous sensitive response to motion with significant variations in the load impedance so presented to the oscillator-mixer cavity.
Claim 13
Dependent Claim
37 words
The apparatus of claim 10 including a modulating diode, a coupling member connected to the modulating diode and disposed in the fringing field of the open transmission line cavity to couple the modulating diode to the cavity.
Claim 14
Dependent Claim
41 words
The apparatus of claim 11 wherein the coupling means is a small loop passed through a hole in the cavity wall immediately adjacent the open coaxial transmission line and a feed-through capacitor interconnecting the modulating diode to a modulating power supply.
Claim 15
Dependent Claim
79 words
The apparatus of claim 1 including a bias assembly secured within said housing and including a bias disC connected to said coaxial conductor, a dielectric member clamped to the housing by said bias disc and defining a first RF by-pass path to said housing, a connector pin connected to the bias disc and projecting outwardly of the housing, and a relatively thin second dielectric member surrounding said connector pin and defining a second RF by-pass path to said housing.
Claim 16
Dependent Claim
45 words
The apparatus of claim 13 wherein said connector pin is mounted within an opening in a threaded metal support and includes a body portion substantially filling said opening, said second dielectric member being a tape-like element disposed between the body portion and the metal support.
References Cited (Backward Citations)
US3611374A
Cited
US3659293A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |