CA1214232A
Expired / Lapsed
CA
⏱️ 0.0 years remaining
Intrusion detector field probe
Assignee: Senstar Security Systems Corp
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Filing: 1982-09-20
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Granted: 1986-11-18
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Expires: 2002-09-20
Abstract
Abstract ABSTRACT OF THE DISCLOSURE This invention relates to a field probe for use with an electromagnetic type of intrusion detector, in which an electromagnetic field emanating from a cable is coupled to a receiving cable and in which a disturbance to the field is detected, thus providing an indication that an intruding body has entered the field. The field probe provides a means for simulating the entrance of an intruding body into the field, and thereby affording means for testing the intrusion detector system and facilitating calibration. The probe consists of an antenna located between the cables with a transmission line connected to the antenna, and a switchable termination to the transmission line for varying the reflection coefficient of the transmission line termination. The phase of the reflected field is thereby changed which simulates the entrance of an intruding body into the detector region.
Inventors
- 👤 R. Keith Harman
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-11-02 12:33
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2491
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
118 words
A field probe for an intrusion detector of the type having a radio frequency electromagnetic emanating cable which has its field coupled to a radio frequency electromagnetic field detecting cable comprising: (a) an antenna for situating generally between said cables, of a kind for receiving a radio frequency signal from said field and reflecting said signal to said detecting cable, (b) a transmission line connected to said antenna, and (c) means for varying the reflection coefficient of the transmission line, whereby the radio frequency signal received from said field by said antenna and reflected thereby to said detecting cable is caused to change with said variation, thus providing a reference for determination of operation Of said intrusion detector.
Claim 2
Dependent Claim
118 words
A field probe for an intrusion detector of the type having a radio frequency electromagnetic emanating cable which has its field coupled to a radio frequency electromagnetic field detecting cable comprising: (a) an antenna for situating generally between said cables, of a kind for receiving a radio frequency signal from said field and reflecting said signal to said detecting cable, (b) a transmission line connected to said antenna, and (c) means for varying the reflection coefficient of the transmission line, whereby the radio frequency signal received from said field by said antenna and reflected thereby to said detecting cable is caused to change with said variation, thus providing a reference for determination of operation Of said intrusion detector.
Claim 3
Dependent Claim
48 words
A field probe as defined in claim 1, in which the means for varying the reflection coefficient of the transmission line is comprised of a termination to said transmission line connected thereto at a location remote from the antenna, and means for changing the phase of said termination.
Claim 4
Dependent Claim
35 words
A field probe as defined in claim 2, in which said termination is comprised of a very high impedance, said means for varying including means for short circuiting said transmission line across said high impedance.
Claim 5
Dependent Claim
17 words
A field probe as defined in claim 3, in which said high impedance is an open circuit.
Claim 6
Dependent Claim
18 words
A field probe as defined in claim 2, in which the termination is comprised of a tuned circuit.
Claim 7
Dependent Claim
17 words
A field probe as defined in claim 2, in which the termination is comprised of a capacitor.
Claim 8
Dependent Claim
17 words
A field probe as defined in claim 2, in which the termination is comprised of an inductor.
Claim 9
Dependent Claim
20 words
A field probe as defined in claim 2, in which the termination is comprised of a length of transmission line.
Claim 10
Dependent Claim
36 words
A field probe as defined in claim 3 or 4, in which the termination is comprised of a semiconductor switch, and further including means for applying a switching current to the switch to change its conductivity.
Claim 11
Dependent Claim
54 words
A field probe as defined in claim 3 or 4 in which the termination is comprised of one or a parallel connected pair of oppositely poled diodes and further including means for applying a D.C. current to one of said pair of diodes to bias and change the conductivity of the diode or diodes.
Claim 12
Dependent Claim
18 words
A field probe as defined in claim 1, 2 or 3 in which the antenna is a dipole.
Claim 13
Dependent Claim
26 words
A field probe as defined in claim 1, 2 or 3 in which the antenna is a dipole having one arm significantly longer than the other.
Claim 14
Dependent Claim
26 words
A field probe as defined in claim 1, 2 or 3 in which the antenna is a wire located in said field generally between said cables.
Claim 15
Dependent Claim
29 words
A field probe as defined in claim 1, 2 or 3 in which the length of the transmission line is a multiple of the wavelength of the electromagnetic field.
Claim 16
Dependent Claim
21 words
A field probe as defined in claim 1, 2 or 3, in which the transmission line is formed of coaxial cable.
Claim 17
Dependent Claim
20 words
A field probe as defined in claim 1, 2 or 3 in which the transmission line is formed of twin-lead.
Claim 18
Dependent Claim
124 words
A field probe for an intrusion detector of the type having a pair of spaced buried leaky coaxial cables in which one cable emanates a radio frequency electromagnetic field and the other is coupled to said field, and has means for detecting variation in the field caused by a body intruding into the field, (a) a buried antenna located generally between said cables for receiving and reflecting electromagnetic energy from said field, (b) a transmission line connected to said antenna, and (c) means for varying the reflection coefficient of the transmission line; whereby said reselected energy is caused to change with said variation in the reflection coefficient of the transmission line, thereby causing variation in said field for detection by said means for detecting.
Claim 19
Dependent Claim
124 words
A field probe for an intrusion detector of the type having a pair of spaced buried leaky coaxial cables in which one cable emanates a radio frequency electromagnetic field and the other is coupled to said field, and has means for detecting variation in the field caused by a body intruding into the field, (a) a buried antenna located generally between said cables for receiving and reflecting electromagnetic energy from said field, (b) a transmission line connected to said antenna, and (c) means for varying the reflection coefficient of the transmission line; whereby said reselected energy is caused to change with said variation in the reflection coefficient of the transmission line, thereby causing variation in said field for detection by said means for detecting.
Claim 20
Dependent Claim
45 words
A field probe as defined in claim 17, in which the means for varying the reflection coefficient of the transmission line includes a termination to the transmission line at a location remote from the antenna, and means for switching the termination across the transmission line.
Claim 21
Dependent Claim
55 words
A field probe as defined in claim 18, including means for short circuiting the transmission line at said remote location during normal operating periods of said intrusion detector, and means for connecting said termination to said transmission line at said remote location in place of said short circuit during test periods of said intrusion detector.
Claim 22
Dependent Claim
16 words
A field probe as defined in claim 19, in itch said termination is a high impedance.
Claim 23
Dependent Claim
35 words
A field probe as defined in claim 19, in which said termination is selected from the group consisting of a tuned circuit, a capacitor, an inductor, a resistor and a further length of transmission line.
Claim 24
Dependent Claim
72 words
A field probe as defined in claim 19, in which the termination is comprised of a parallel connected pair of oppositely poled diodes, and further including means for applying bias current to said diodes to render at least one of them non-conductive to provide a short circuit termination for one polarity and an open circuit for the other polarity of a radio frequency signal which may be carried by the transmission line.
Claim 25
Dependent Claim
18 words
A field probe as defined in claim 19, 20 or 22, in which the antenna is a dipole.
References Cited (Backward Citations)
No citation records indexed.
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