US4721945A — Simulated targets for detection systems

Claim 1

Independent Claim 124 words

In combination, an RF intrusion detection system operating at a first RF frequency and having at least one RF transmission line with a radiating RF field therearound; means responsive to said radiating RF field to provide a corresponding return signal; a simulated target consisting of an electrical conductor having an effective electrical length located in said field, said simulated target being in the near field of said radiating RF field to thereby affect said return signal; and means in the intrusion system for altering the effective electrical length of the conductor so that at the altered effective electrical length said simulated target causes a change in said RF return signal which is similar to the change caused by an intruder entering said RF field.

Claim 2

Dependent Claim 124 words

In combination, an RF intrusion detection system operating at a first RF frequency and having at least one RF transmission line with a radiating RF field therearound; means responsive to said radiating RF field to provide a corresponding return signal; a simulated target consisting of an electrical conductor having an effective electrical length located in said field, said simulated target being in the near field of said radiating RF field to thereby affect said return signal; and means in the intrusion system for altering the effective electrical length of the conductor so that at the altered effective electrical length said simulated target causes a change in said RF return signal which is similar to the change caused by an intruder entering said RF field.

Claim 3

Dependent Claim 20 words

The combination of claim 1 wherein said altered effective electrical length of the conductor is resonant at said first frequency.

Claim 4

Dependent Claim 33 words

The combination as set out in claim 1 wherein the conductor consists of at least two sections, and wherein said means for altering the effective length of the conductor consists of switch means.

Claim 5

Dependent Claim 20 words

The combination as set out in claim 1, wherein said change in said signal return is a change in magnitude.

Claim 6

Dependent Claim 20 words

The combination as set out in claim 1, wherein said change in said signal return is a change in phase.

Claim 7

Dependent Claim 27 words

The combination as set out in claim 1 or claim 2 wherein the transmission line and the conductor are buried in a medium having varying electrical characteristics.

Claim 8

Dependent Claim 22 words

The combination as set out in claim 1, claim 2 or claim 3 wherein the transmission line is a radiating coaxial cable.

Claim 9

Dependent Claim 25 words

The combination as set out in claim 1, claim 2 or claim 3 wherein the conductor is supported on the outside of the transmission line.

Claim 10

Dependent Claim 93 words

In combination with an RF intrusion detection system for detection of targets, the system operating at a first frequency and having at least one transmission line with a radiating RF field therearound and means responsive to said RF field to provide a return signal having a stationary response profile in the absence of a target, a simulated target consisting of electrical conductor means located in said RF field, said conductor means producing predetermined markers in said return signal response profile, whereby changes in ambient conditions will produce detectable variations in said return signal.

Claim 11

Dependent Claim 93 words

In combination with an RF intrusion detection system for detection of targets, the system operating at a first frequency and having at least one transmission line with a radiating RF field therearound and means responsive to said RF field to provide a return signal having a stationary response profile in the absence of a target, a simulated target consisting of electrical conductor means located in said RF field, said conductor means producing predetermined markers in said return signal response profile, whereby changes in ambient conditions will produce detectable variations in said return signal.

Claim 12

Dependent Claim 30 words

The combination as set out in claim 9, wherein said conductor means includes a plurality of passive conductors longitudinally spaced from one another along the length of the transmission line.

Claim 13

Dependent Claim 20 words

The combination as set out in claim 10 wherein said conductors are supported on the outside of the transmission line.

Claim 14

Dependent Claim 17 words

The combination as set out in claim 9 wherein the conductor means is resonant at said frequency.

Claim 15

Dependent Claim 22 words

The combination as set out in claim 9, claim 10 or claim 8, wherein the transmission line is a radiating coaxial cable.

Claim 16

Dependent Claim 31 words

The combination as set out in claim 9, claim 10 or claim 8, wherein the transmission line is a radiating coaxial cable and said conductors are conductive sleeves around the cable.

Claim 17

Dependent Claim 28 words

The combination as set out in claim 9, claim 10 or claim 8, wherein the transmission line and conductors are buried in a medium having varying electrical characteristics.

Claim 18

Dependent Claim 82 words

In an RF intrusion detection system operating at a first RF frequency, at least one transmission line radiating an RF field into a detection zone; means responsive to said radiated RF field to provide a return signal having a stationary RF response profile in the absence of a target in said detection zone; and a simulated target consisting of electrical conductor means having known effective electrical characteristics located in said detection zone to produce predetermined markers in said return signal response profile.

Claim 19

Dependent Claim 82 words

In an RF intrusion detection system operating at a first RF frequency, at least one transmission line radiating an RF field into a detection zone; means responsive to said radiated RF field to provide a return signal having a stationary RF response profile in the absence of a target in said detection zone; and a simulated target consisting of electrical conductor means having known effective electrical characteristics located in said detection zone to produce predetermined markers in said return signal response profile.

Claim 20

Dependent Claim 37 words

The intrusion detection system of claim 16, wherein said simulated target includes a plurality of passive conductors for producing said markers in said response profile, whereby changes in ambient conditions produce detectable variations in said return signal.

Claim 21

Dependent Claim 42 words

The intrusion detection system of claim 16, further including means for changing the effective electrical characteristics of said simulated target to produce a change in said response profile which is similar to the change produced by an intruder entering said detection zone.

Claim 22

Dependent Claim 21 words

The intrusion detection system of claim 18, wherein said simulated target is located in the near field of said transmission line.

Claim 23

Dependent Claim 32 words

The intrusion detection system of claim 19, wherein said means for changing the effective electrical characteristics of said simulated target comprises switch means for changing the length of said electrical conductor means.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-01-25	1991-07-27	1992-01-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-01-25	1995-07-27	1996-01-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-01-25	1999-07-27	2000-01-26	$7700.00	Window Closed / Lapsed

Simulated targets for detection systems

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